Floor cleaning machine with a pre-tensioned suction foot

Abstract

A floor cleaning machine is shown and described, comprising a machine frame to which a chassis is attached, a suction foot with a suction chamber open to the floor surface to be cleaned, a support arm assembly pivotably mounted on the machine frame about a horizontal pivot axis, the suction foot being spaced apart from the pivot axis on the support arm assembly so that the vertical position of the suction foot relative to the floor surface to be cleaned is adjustable between a raised position and a lowered position, and a linear actuator having a first coupling end and a second coupling end, the distance of the first coupling end relative to the second coupling end being adjustable along an adjustment axis, and the first coupling end being connected to the support arm assembly.wherein the suction foot is moved between the lowered and raised positions by adjusting the distance between the coupling elements, wherein the second coupling end is slidably mounted on the machine frame parallel to the adjustment axis, and wherein a pretensioning element is provided which is coupled to the second coupling end in such a way that it pretensions the linear actuator in the direction along the adjustment axis in which the first coupling end is moved to lower the suction foot onto the floor surface to be cleaned.

Description

[0001] The present invention relates to a floor cleaning machine with a machine frame to which a chassis is attached for moving the floor cleaning machine over a floor surface to be cleaned, with a suction foot on which a suction chamber open to the floor surface to be cleaned is formed and which is connected to a vacuum source of the floor cleaning machine, with a support arm arrangement which is pivotably mounted on the machine frame about a horizontal pivot axis, wherein the suction foot is mounted on the support arm arrangement at a distance from the pivot axis, so that the vertical position of the suction foot relative to the floor surface to be cleaned is adjustable between a raised position, in which the suction foot is spaced away from the floor surface to be cleaned, and a lowered position, in which the suction foot rests against the floor surface to be cleaned.

[0002] Conventional floor cleaning machines, and in particular scrubber-dryers, have a chassis on the machine frame for moving the floor cleaning machine over a floor surface to be cleaned, and a cleaning device is provided on the machine frame that can engage with the floor surface to be cleaned and apply cleaning fluid to the floor surface.

[0003] Furthermore, such floor cleaning machines have a so-called suction foot, which, viewed in the direction of travel, is arranged behind the cleaning unit and is designed to collect the applied cleaning fluid from the floor surface. For this purpose, the suction foot preferably has two sealing lips extending essentially parallel to each other from a suction foot base, the edges of which furthest from the suction foot base lie in a common contact plane, so that when the suction foot rests on the floor surface, a suction chamber is defined by the sealing lips. A vacuum source, such as a suction turbine, provided on the floor cleaning machine creates a vacuum in this suction chamber via the suction foot base, so that cleaning fluid can be drawn out of the suction chamber and thus from the floor surface.

[0004] During cleaning operation, the suction foot is in the lowered position and thus in contact with the floor surface to be cleaned. In the During normal operation, when the machine is moved from one work site to the next, the suction foot is first moved from the lowered position to the raised position, in which it is spaced away from the ground surface to avoid wear on the suction foot.

[0005] To ensure that the cleaning fluid is effectively suctioned from the floor surface during cleaning when the suction foot is in the lowered position, it is necessary that the suction foot is pressed against the floor with sufficient force. It is generally known to design the suction foot to be sufficiently heavy so that its weight alone is enough to generate the required pressure. However, this has the disadvantage that a relatively large force is required to move the suction foot from the lowered to the raised position. This makes the suction foot assembly cumbersome to operate.

[0006] Floor cleaning machines are illustrated, for example, in WO 2015 / 010723 A1, in EP 2 954 817 A1 and in US 2013 / 0212819 A1.

[0007] Therefore, the object of the present invention is to provide a floor cleaning machine with a suction foot that can be moved between a lowered and a raised position, in which the suction foot is pressed with sufficient pressure onto the floor surface to be cleaned, whereby the weight of the suction foot can be kept low.

[0008] This problem is solved by a floor cleaning machine according to claim 1. Advantageous further developments are the subject of the dependent claims.

[0009] The floor cleaning machine according to the invention has a machine frame to which a chassis is attached in order to move the floor cleaning machine over a floor surface to be cleaned, and a suction foot on which a suction chamber open to the floor surface to be cleaned is formed, which is connected to a vacuum source of the floor cleaning machine.

[0010] Furthermore, a holding arm arrangement is provided which is pivotably mounted on the machine frame about a horizontal pivot axis, wherein the suction foot is attached to the holding arm arrangement at a distance from the pivot axis, so that the vertical position of the suction foot relative to the floor surface to be cleaned is adjustable between a raised position, in which the suction foot is spaced away from the floor surface to be cleaned, and a lowered position, in which the suction foot rests against the floor surface to be cleaned.

[0011] Furthermore, a linear actuator is provided, comprising a first coupling end and a second coupling end, wherein the distance of the first coupling end relative to the second coupling end is adjustable along an adjustment axis, and wherein the first coupling end is connected to the holding arm assembly. By adjusting the distance between the coupling ends, the suction foot can be moved between the lowered and raised positions, with the second coupling end being slidably mounted on the machine frame parallel to the adjustment axis.

[0012] According to the invention, the second coupling end is slidably mounted on the machine frame in a direction that runs at an angle of less than 90°, preferably parallel, to the adjustment axis. Finally, a preloading element is provided which is coupled to the second coupling end in such a way that it preloads the linear actuator in the direction along the adjustment axis in which the first coupling end is moved to lower the suction foot onto the floor surface to be cleaned.

[0013] In the floor cleaning machine according to the invention, the second coupling end of the linear actuator, which moves the suction foot from the lowered position to the raised position, is subjected to a preload force when the second coupling end is displaced relative to the machine frame during the movement of the linear actuator. During this displacement movement, the direction of which is either parallel to the adjustment axis or at least at an angle of less than 90° to it, a spring can, for example, be compressed, which then exerts the preload on the second coupling end and thus on the linear actuator. Since the linear actuator is rigidly connected to the support arm assembly, the preload presses the suction foot against the floor surface to be cleaned.

[0014] The pre-tensioning element generates a force that acts in addition to the weight of the suction foot, pressing it against the floor surface with a greater force than its own weight. This ensures that the suction foot seals tightly against the floor surface being cleaned and that sufficient suction is achieved to remove the cleaning fluid from the floor.

[0015] The design according to the invention avoids the need for the suction foot to be heavy enough to achieve the required total contact force. Furthermore, the linear actuator does not require complex control, such as via a control loop, to generate the necessary contact force. Instead, the linear actuator simply moves between the positions required for the lowered and raised positions. Finally, another advantage of the present invention is that the additional contact force generated by the preload element only acts when the suction foot is in the lowered position. The additional force does not act when the suction foot is raised. This has the further advantage that when the suction foot is to be pivoted in the raised position, an additional weight does not have to be pivoted along with it, which would be undesirable. The same applies analogously to the raising itself.If an additional weight were attached to the suction foot to increase the pressure, this weight would have to be lifted along with the suction cup when lifting, which would require a larger actuator, but this is not necessary in the present invention.

[0016] In In a preferred embodiment, the suction chamber is bounded by at least one elastic sealing lip extending towards the floor surface to be cleaned. A sealing lip ensures that the suction chamber is reliably sealed against the floor surface and that air can only flow into the suction chamber at the points where this is desired, for example, through openings. However, such sealing lips require sufficient contact pressure to achieve the sealing effect, so the use of the pre-tensioning element according to the invention is particularly advantageous in a design with sealing lips.

[0017] Furthermore, it is preferred if the second coupling end of the linear actuator is guided in a guide rail on the machine frame. This is a simple design for implementing the movable mounting of the second coupling end of the linear actuator on the machine frame.

[0018] InIn another preferred embodiment, the pretensioning element has a flexible cable section extending between a first and a second end. In this embodiment, the second coupling end of the linear actuator is connected to a guide element along which the cable section is guided such that it is movable relative to the second coupling end and is displaced relative to the guide element when the linear actuator is moved from the raised position to the lowered position to move the suction foot. Finally, the first end of the pretensioning element is connected to the first coupling end, and the second end of the pretensioning element is rigidly connected to the machine frame.

[0019] This design ensures that when the linear actuator is moved such that the suction cup is moved from the raised position to the lowered position, the cable section is displaced relative to the second coupling end, as the first coupling end, which is connected to the holding assembly, is moved. In this process, the preload element, or a spring section within the preload element, is tensioned, and the resulting restoring force of the spring element acts on the guide element, so that the spring element exerts an overall force on the linear actuator. This force provides the additional pressure even when the linear actuator has reached the position in which the suction cup is in the lowered position.

[0020] Preferably, the preload element can have a spring section, in particular in the form of a helical spring, which is tensioned when the linear actuator is moved into the position corresponding to the lowered position. It is particularly preferred if the spring section is provided at the second end of the preload element, which is rigidly connected to the machine frame.

[0021] In order to design the assembly consisting of the linear actuator on the one hand and the preload element on the other hand in a space-saving and at the same time efficient manner, it is particularly preferred if the preload element, consisting of the cable section and the spring section, runs in a plane in which the adjustment axis also runs or to which the adjustment axis is parallel.

[0022] InIn an alternative embodiment to the design with the cable section, a spring element can be provided against which the second coupling end of the linear actuator rests when the linear actuator has moved into the position corresponding to the lowered position. The spring element then exerts a force on the second coupling end, which in turn ensures that a pressure force is exerted on the suction cup. In Preferably, the second coupling end can be spaced apart from the free end of the spring element in the raised position. This prevents the spring action from having to be overcome when lifting the element further by hand.

[0023] InIn another alternative embodiment, a spring element can be provided through which the second coupling end of the linear actuator is connected to the machine frame. In this embodiment as well, an additional force is exerted on the second coupling end of the linear actuator in the lowered position, which in turn results in an increased contact force for the suction cup. In a further preferred manner, the connection between the first end of the spring element and the second coupling end, and / or the connection between the second end of the spring element and the machine frame, can be provided with play. This, in turn, allows the suction cup to be raised further from the raised position without having to work against the spring force.

[0024] In the floor cleaning machine according to the invention, the linear actuator can be designed as a hydraulic cylinder, a linear motor or a pneumatic cylinder.

[0025] In theThe present invention is described below with reference to a drawing showing only preferred embodiments, wherein Fig. 1 is a side view of an embodiment of a floor cleaning machine according to the invention, Fig. 2 is a perspective view of the suction foot of the embodiment. Fig. 1 Fig. 3 is a perspective view of the linear actuator and the preload element of the exemplary embodiment. Fig. 1 Figures 4 and 5 are schematic representations of the structure for holding the suction cup of the exemplary embodiment. Fig. 1Figures 6 and 7 are schematic representations of the structure for holding the suction foot of a second embodiment in the lowered and raised positions, Figures 8 and 9 are schematic representations of the structure for holding the suction foot of a third embodiment in the lowered and raised positions, and Figures 10 and 11 are schematic representations of the structure for holding the suction foot of a fourth embodiment in the lowered and raised positions.

[0026] Figure 1Figure 1 shows a side view of a first embodiment of a floor cleaning machine 1 according to the invention, which has a machine frame 3 on which a chassis consisting of a front wheel 5 and two rear wheels 7 is provided, wherein the front wheel 5 is steerable and equipped with a drive. By means of the chassis consisting of the wheels 5 and 7, the floor cleaning machine 1 can be moved over a floor surface 9 to be cleaned.

[0027] The floor cleaning machine 1 has a cleaning unit 11 that can be lowered and thus brought into contact with the floor surface 9 to be cleaned. The cleaning unit 11 is arranged between the front wheel 5 and the rear wheels 7. Such cleaning units 11 are well known from the prior art, so no further explanation is necessary. The cleaning unit 11 is designed so that cleaning fluid can be applied to the floor surface 9 to be cleaned, and brushes are also provided that can engage with the floor surface 9 when the cleaning unit 11 is lowered. Instead of brushes, pads or other engagement elements can also be provided on the cleaning unit.

[0028] In theIn the present embodiment, the floor cleaning machine 1 is designed as a ride-on machine, in which a user sits on a seat 13 attached to the machine frame 3 and controls the machine. However, the present invention is not limited to such ride-on machines, but can also be applied to hand-operated floor cleaning machines.

[0029] Viewed against the direction of travel, a suction foot assembly 15 is attached to the machine frame 3 behind the rear wheels 7, wherein the suction foot assembly 15 is in Figure 2 shown in a perspective view.

[0030] The suction foot assembly 15 comprises the actual suction foot 17, which includes a suction foot base 19 from which a rear sealing lip 21 extends downwards. Furthermore, a front sealing lip is provided, which runs essentially parallel to the rear sealing lip 21, so that when the downward-facing ends of the sealing lips 21 rest on the floor surface 9 to be cleaned, a suction chamber is formed between them. This chamber is open towards the floor surface 9 to be cleaned. The suction chamber is connected via a port 23 provided on the suction foot base 19 and a hose 25 to a vacuum source provided in the floor cleaning machine 1 (not shown in detail). Using the vacuum source, cleaning fluid applied to the floor surface 9 by the cleaning unit 11 can be extracted from the suction chamber at the suction foot 17.However, this requires that the suction foot 17 is lowered onto the floor surface 9 to be cleaned.

[0031] For this purpose, the suction foot 17 can be positioned between a Figure 1The suction foot assembly 15 is pivoted about a horizontal axis 27 in the lowered position shown, in which the sealing lips 21 rest on the floor surface 9 to be cleaned, and in a raised position, with the sealing lips 21 being spaced apart from the floor surface 9 to be cleaned. The suction foot assembly 15 has a support arm assembly for this purpose, which comprises support arms 29 extending between the horizontal axis 27 and the suction foot 17. One end of each support arm 29 is pivotably connected to the machine frame 3 about the horizontal axis 27, while the other end is rigidly hinged to the suction foot 17. Furthermore, the support arm assembly has an actuating arm 31, which is rigidly connected to the support arms 29 and extends upwards away from the horizontal axis 27.The end of the actuating arm 31 furthest from the horizontal axis 27 is connected to a first coupling end 33 of a linear actuator 35, which also has a second coupling end 37 that is slidably mounted in the machine frame 3 in a straight guide rail 39. The linear actuator 35 is designed such that the distance between the first coupling end 33 and the second coupling end 37 can be adjusted along an adjustment axis 41 running between them. In this embodiment, the guide rail 39 runs parallel to the adjustment axis 41. However, it is also conceivable that the adjustment axis and the guide rail form an angle of less than 90°.

[0032] Two deflection pulleys 43 are rotatably mounted at the second coupling end 37 of the linear actuator 35. Furthermore, a preload element is provided, which in this preferred embodiment comprises a cable section 45 and a spring section 47 in the form of a helical spring. A first end 49 of the preload element, consisting of the cable section 45 and the spring section 47, is connected to the first coupling section 33, and a second end 51 of the preload element, formed on the spring section 47, is fixedly connected to the machine frame 3 (see Figure 4The cable section 45 is guided around the deflection pulleys 43, so that when the distance between the first and second coupling ends 33, 37 of the linear actuator 35 is changed, the preload element moves relative to the second coupling end 37. Specifically, when the distance between the first coupling end 33 and the second coupling end 37 of the linear actuator 35 increases, the spring section 47 of the preload element is tensioned. In this configuration, the tension of the spring section 47 exerts a force on the linear actuator 35, which runs along the adjustment axis 41 and is directed towards the second coupling end 33. The preload is thus directed in the direction in which the first coupling end 33 is moved to lower the suction foot 17 into the lowered position.

[0033] From the Figures 4 and 5The figures, which schematically illustrate the previously described structure of the suction foot assembly 15 and the lifting assembly provided for it, show that in this embodiment the pretensioning element, which is formed from the cable section 45 and the spring section 47, defines a plane in which it extends by its course over the deflection pulley 43. The adjusting axis 41 also runs in this plane. This space-saving design is also due to Fig. 3 to recognize.

[0034] Furthermore, it is assumed from the Figs. 4 and 5 highlighting the functionality of the first embodiment.

[0035] Starting from Figure 5Figure 15, which shows the suction foot assembly 15 in the raised position, shows that when the linear actuator 35 is adjusted such that the distance between the first coupling end 33 and the second coupling end 37 increases, the actuating arm 31 pivots clockwise about the horizontal axis 27, causing the support arms 29 to also pivot clockwise. This lowers the suction foot 17 onto the floor surface 9 to be cleaned, and the sealing lips 21 come into contact with it. Simultaneously, as the linear actuator 35 extends, the cable section 45, one end 49 of which is connected to the first coupling end 33, is moved around the second coupling end 37 by rotating the deflection pulleys 43, thereby tensioning the spring section 47.The tension of the spring section 47 exerts a force on the deflection roller 43 and the second coupling end 37, acting on the linear actuator 35 along the adjustment axis 41, with the force directed towards the first coupling end 33. This preload acts in the direction along the adjustment axis 41 in which the first coupling end 33 is moved to lower the suction foot onto the floor surface to be cleaned.

[0036] This in turn causes a torque to be exerted on the actuating arm 31, which is associated with a pressure force for the suction foot 17 against the floor surface 9 to be cleaned. Therefore, when the linear actuator 35 is adjusted such that the suction foot 17 is in the lowered position, in contact with the floor surface 9 to be cleaned, an additional force is automatically exerted on the suction foot 17 against the floor surface 9 due to the preload of the preloading element 45, 47, so that its sealing lips make a tight seal against the floor surface 9. No additional weight is required on the suction foot 17 to generate this additional pressure force.

[0037] In the Figures 6 and 7A second embodiment of a floor cleaning machine according to the invention is shown, which differs from the first embodiment only in that the preloading element with which the linear actuator 35 or its second coupling end 37 is preloaded along the adjustment axis 41 differs from that of the first embodiment. As the Figures 6 and 7 As can be seen, a spring element 53 is arranged opposite the second coupling end 37 of the linear actuator 35 on the guide rail 39. When the linear actuator 35 is in its first, retracted position (see Figure 7), the actuating arm 31 is pivoted counterclockwise, and the suction foot assembly 15 is in the raised position, in which the suction foot 17 is spaced away from the floor surface 9 to be cleaned. When the linear actuator 35 is extended so that the distance between the coupling ends 33, 37 along the adjustment axis 41 increases, the actuating arm 31, and thus also the holding arm 29, is pivoted clockwise about the horizontal axis 27, so that the suction foot assembly 15 is moved into the lowered position, in which the suction foot 17 rests against the floor surface 9 to be cleaned ( Figure 6The second coupling end 37 then comes into contact with the spring element 53 and compresses it. This, in turn, pre-tensions the entire linear actuator 35 along the adjustment axis 41 in the direction of the first coupling end 33, so that, due to the compression of the spring element 53, an additional force or torque is exerted on the actuating arm 31. This additional force results in an additional contact force for the suction foot 17, which presses it against the floor surface 9 to be cleaned. Thus, in this embodiment as well, the suction foot 17 is subjected to an additional force, leading to an improved seal between the sealing lips and the floor surface to be cleaned, without requiring any additional weight on the suction foot 17. This embodiment is further designed such that the second coupling end 37, in the raised position ( Fig. 7) is spaced apart from the free end of the spring element 53. This prevents the user from having to overcome the effect of the spring element 53 when lifting the device manually from the raised position.

[0038] The in the Figures 8 and 9 The third embodiment of a floor cleaning machine according to the invention differs from the second embodiment in that in this case the linear actuator 35 must be moved together, i.e. the distance between the first and second coupling ends 33, 37 is reduced in order to move the suction foot 17 out of the raised position ( Figure 9 ) into the lowered position ( Figure 8 ) to lower.

[0039] The Figures 8 and 9It can be seen that a spring element 53 is provided at the end of the guide rail facing the linear actuator 35, which then comes into contact with the second coupling element 37 when the linear actuator 35 is moved together to raise the suction foot 17 from the raised position ( Figure 9 ) into the lowered position ( Figure 8) to lower, in which the sealing lips come into contact with the floor surface 9 to be cleaned. Here too, the holding arm 29 pivots clockwise about the horizontal axis 27. When the suction foot 17 is in the lowered position, the spring element 53 is compressed and exerts an additional force on the second coupling end 37, which runs along the adjustment axis 41 and is directed in the same direction as the first coupling end 33 when the suction foot 17 is moved into the lowered position. This force causes a force to be exerted on the entire linear actuator 35, which is directed in the same direction as the first coupling element 33 moves when the suction foot 17 is lowered. This also results in an additional pressure force on the suction foot 17 towards the floor surface 9 to be cleaned, without requiring any additional weight on the suction foot 17.Here too, this additional pressure force results in a better seal between the sealing lips on the one hand and the base surface 9 on the other.

[0040] This embodiment is also constructed such that the second coupling end 37 is in the raised position ( Fig. 9 ) is arranged at a distance from the free end of the spring element 53. This also prevents the user from having to work against the action of the spring element 53 when manually lifting the device from the raised position.

[0041] In the Figures 10 and 11Figure 4 shows a fourth embodiment of a floor cleaning machine according to the invention, specifically the assembly for raising and lowering the suction foot 17. This embodiment differs from those described above in that a spring element 53 is rigidly connected at its first end 55 to the second coupling end 37 of the linear actuator 35, while the second end 57 of the spring element 53 is rigidly connected to the machine frame 3. However, the rigid connection between the spring element 53 and the second coupling end 37 of the linear actuator 35 may have some play. Furthermore, the connection between the spring element 53 and the machine frame 3 may also have some play. InIn both cases, the advantage is that when the suction foot 17 is pivoted while in the raised position, the spring does not need to be stretched during the slight lifting associated with the pivoting. This would otherwise place an additional burden on the operator.

[0042] In the raised position of the suction foot 17, which in Figure 11 As shown, the linear actuator 35 is moved apart along the adjustment axis 41 in such a way that the distance between the first coupling end 33 and the second coupling end 37 is at its maximum. InIn this case, the spring element 53 is not extended. However, when the suction foot 17 is moved into the lowered position, in which it rests against the floor surface 9 to be cleaned, by pivoting the holder arm 29 clockwise about the horizontal axis 27, thereby retracting the linear actuator 35 so that the distance between the coupling ends 33, 37 along the adjustment axis 41 decreases, the spring element 53 is extended. This causes a preload on the second coupling element 37, with this preload being directed in the same direction as the movement of the first coupling element 33 when it is moved into the lowered position. This preload, in turn, causes an additional force on the actuating arm 31, which results in an additional contact force on the suction foot 17.In this case, too, the preload caused by the spring element 53 results in an additional pressure force on the suction foot 17, without requiring any additional weight.

[0043] In all the exemplary embodiments, the preload or spring elements 47, 51, 53 exert an additional preload on the linear actuator 35, directed in the same direction as the movement of the first coupling element 33 when the suction foot 17 is lowered. This preload, in turn, causes an additional contact force on the suction foot 17. This has the advantage that, although a contact force is exerted on the suction foot 17, this is not associated with any additional weight on the suction foot 17. It can still be operated in a simple manner. Reference sign

[0044] 1 Floor cleaning machine 3 Machine frame 5 Front wheel 7 Rear wheel 9 Floor surface 11 Cleaning unit 13 Seat 15 Suction foot assembly 17 Suction foot 19 Suction foot base 21 Rear sealing lip 23 Connection 25 Hose 27 Horizontal axis 29 Holding arm 31 Actuating arm 33 First coupling end 35 Linear actuator 37 Second coupling end 39 Guide rail 41 Adjustment axis 43 Deflection pulley 45 Cable section 47 Spring section 49 First end - pretensioning element 51 Second end - pretensioning element 53 Spring element 55 First end - spring element 57 Second end - spring element

Claims

1. A floor cleaning machine with a machine frame (3) to which a chassis is attached for moving the floor cleaning machine (1) over a floor surface (9) to be cleaned, with a suction foot (17) on which a suction chamber open to the floor surface (9) to be cleaned is formed, which is connected to a vacuum source of the floor cleaning machine (1), with a holding arm arrangement (29, 31) which is pivotably mounted on the machine frame (3) about a horizontal pivot axis (27), wherein the suction foot (17) is attached to the holding arm arrangement (29, 31) via the pivot axis (27), so that the vertical position of the suction foot (17) relative to the floor surface (9) to be cleaned is adjustable between a raised position, in which the suction foot (17) is spaced away from the floor surface (9) to be cleaned, and a lowered position, in which the suction foot (17) rests against the floor surface (9) to be cleaned, with a linear actuator (35) having a first coupling end (33) and a second coupling end (37), wherein the distance between the first coupling end (33) and the second coupling end (37) is adjustable along an adjustment axis (41), wherein the first coupling end (33) is connected to the holding arm arrangement (29, 31), wherein the suction foot (17) is moved between the lowered and raised positions by adjusting the distance between the coupling elements (33, 37), wherein the second coupling end (37) is slidably mounted on the machine frame (3) in a direction which runs at an angle of less than 90°, preferably parallel, to the adjustment axis (41), characterized in that a pre-tensioning element (47, 53) is provided which is coupled to the second coupling end (37) in such a way that it pre-tensions the linear actuator (35) in the direction along the adjustment axis (41) in which the first coupling end (33) is moved to lower the suction foot (17) onto the floor surface (9) to be cleaned.

2. The floor cleaning machine according to claim 1, wherein the suction chamber is limited by at least one elastic sealing lip (21) extending towards the floor surface to be cleaned.

3. The floor cleaning machine according to claim 1 or 2, wherein the second coupling end (37) is guided in a preferably straight guide rail (39) formed on the machine frame (3).

4. The floor cleaning machine according to one or more of claims 1 to 3, wherein the pre-tensioning element has a flexible rope section (45) and extends between a first and a second end (49, 51), wherein the second coupling end (37) is connected to a guide element (43) along which the rope section (45) is guided in such a way that it is movable relative to the second coupling end (37), and wherein the first end (49) of the pre-tensioning element is connected to the first coupling end (33) and the second end (51) of the pre-tensioning element is connected to the machine frame (3).

5. The floor cleaning machine according to claim 4, wherein the pre-tensioning element has a spring section (47), preferably a coil spring section.

6. The floor cleaning machine according to claim 5, wherein the spring section (47) extends away from the second end (51) and the rope section (45) runs between the spring section (47) and the first end (49) of the pre-tensioning element.

7. The floor cleaning machine according to one or more of claims 4 to 6, wherein the pre-tensioning element (45, 47) extends in a plane to which the adjustment axis (41) runs parallel.

8. The floor cleaning machine according to one or more of claims 4 to 7, wherein the guide element is designed as a deflection roller (43) rotatably mounted on the second coupling end (37).

9. The floor cleaning machine according to one or more of claims 1 to 3, wherein the second coupling end (37) in the lowered position is supported on a free end of a spring element (53) which extends parallel to the adjustment axis (41) and which is attached to the machine frame (3) with a further end spaced apart from the free end.

10. The floor cleaning machine according to claim 9, wherein the second coupling end (37) is spaced apart from the free end of the spring element (53) in the raised position.

11. The floor cleaning machine according to one or more of claims 1 to 3, wherein a spring element (53) is provided which is connected at a first end (55) to the second coupling end (37) and which is connected at a second end (57) to the machine frame (3).

12. The floor cleaning machine according to claim 11, wherein the connection of the first end (55) to the second coupling end (37) and / or the connection between the second end (57) and the machine frame (3) is provided with play.

13. The floor cleaning machine according to one or more of claims 1 to 12, wherein the linear actuator (35) is designed as a hydraulic cylinder, linear motor, or pneumatic cylinder.

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