WATER SUCTION DEVICE IN A COMBINED WET SCRUBBING MACHINE HAVING A ROTATABLE DISK-SHAPED BRUSH

TECHNICAL FIELD

The present invention relates to a water suction device in a combined wet scrubbing machine having a rotatable disk-shaped brush intended to bear against the floor to be cleaned, means for feeding fresh water and detergent in the center of the brush, a ring surrounding the brush radially and rotatable with the brush, said ring being provided with on one hand a plurality of suction nozzles placed rotation- symmetric ally on the ring for sucking waste water and on the other hand a plurality of angularly set and likewise rotation- symmetrically placed blades intended to bear slidingly against the floor to scrape together the waste water from an outer edge to an inner edge, so that it may be removed through the suction nozzles.

In the present context, the term "brush" is used as a generic term, which comprises brushes, scourers, and the like that are used in wet cleaning with cleaning machinery.

BACKGROUND ART A combined wet scrubbing machine scrubs floors and sucks up water at the same time, so that no extra machine for sucking up the water is necessary. For many years, the water sucking system in such machines has been formed by a suction scraper mounted at the rear end of the machine, which has made it difficult to maneuver the machine so that the suction scraper came into position for sucking up the used, now dirty water, the waste water, in all places.

Therefore, it has been proposed to provide scraper blades and suction nozzles around the periphery of the brush, and water suction devices of the kind mentioned by way of introduction are previously known from WO 92/16139 and WO 93/15646, for example. Neither the number of suction nozzles, nor the number of blades is stated, but in the shown embodiments six suction nozzles and twelve blades are used. Further, all blades are shown as being straight, comparatively short and identical to one another, and the attachment of the blades to the ring is not described.

In the water suction device of WO 92/16139, the suction nozzles extend up to the top side of the rotatable ring, and thereabove there is an stationary, downwards open ring, which is sealed against the rotatable ring by means of large diameter seals and collects

the waste water coming up through the nozzles, so that it can be drawn off through an outlet provided on the stationary ring. In order to control the pressure of the blades against the floor automatically, a spring may be mounted on the top side of each blade at the locations where the blades are attached to the rotatable rin ¹ gO.-

The use of large diameter seals gives rise to drawbacks, which are eliminated by the water suction device disclosed in WO 93/15646. Here the waste water from the suction nozzles in the rotatable ring is directed to a hub, either through conduits in a brush holder integrated with the ring or in hoses or pipes extending on top of the brush holder. At the hub, the conduits, hoses or pipes discharge into a first U-shaped ring that is open upwards and is rotatable with the brush, and this first ring is surrounded by a matching downwards open stationary second U-shaped ring. The U-shaped rings are sealed against each other, but thanks to the considerably reduced diameter, the sealing problems are easier to solve. Further, each blade is mounted on a component that is axially movable in a recess in the ring, and the component can be locked in its intended position in the ring by means of a locking screw. Such a design is complicated and costly. Alternatively, the ring may be provided with an internal thread, and the top portion of the brush may be provided with a corresponding external thread, so that the brush may be adjusted axially in relation to the blades by being screwed further into or out of the ring. Also in this case there is a locking screw for preventing undesired changes of the relative positions. Thus, the automatic control of the pressure of the blades against the floor is abandoned, a standard brush can not be used, and the large diameter of the thread may make it difficult to enter the thread correctly when the brush is to be screwed into the ring.

In US 4 000 538 a combined wet scrubbing machine is disclosed, where the rotatable ring is provided with two lips or skirts, an inner one and an outer one, which between themselves form an annular suction chamber. The ring is mounted floatingly in relation to the brush by means of one or more intermediate flexible arms, for example three arms spaced apart 120°, which are movably linked on one hand to a waste water collecting hub and on the other hand to the top side of the ring. As the brush is mounted on the hub, the ring with the suction chamber is mounted floatingly relative to the brush. However, there is no indication that any other force than the one resulting from the weight of the ring would contribute in pressing the lips/skirts against the floor.

BRIEF DISCLOSURE OF THE INVENTION

The object of the present invention is to provide a water suction device that is simpler and less costly to manufacture while maintaining or improving the water suction capability of the device.

This object is achieved in the water suction device stated in the introductory portion in that according to the invention the blades are of two kinds, of which the ones that are located by the suction nozzles are completely bent backwards at their rear ends in the direction of rotation, so that the backwards bent rear ends surround the suction nozzles for catching the waste water, and the ones that are located between the suction nozzles are substantially straight. Preferably, the suction nozzles are three in number. Hereby, the water suction device will be simpler and less costly to manufacture, and the backwards bent ends of the blades contribute efficiently in improving or at least maintaining the water suction capability of the device in spite of the reduction from six to three suction nozzles.

The substantially straight blades suitably are lightly bent in arcuate shape towards the brush, and preferably they are of such length in the direction of rotation that each of them covers a rotational angle on the order of 30°. Thereby, the dirty waste water will be retained efficiently inside of the blades and be fed inwards toward the suction nozzles.

It is suitable that the ring is divided axially into an upper member and a lower member, that the blades extend through apertures in the lower member and have base portions above the lower member, and that means are provided for holding the upper member against the lower member while clamping the base portions. Such an attachment of the blades to the ring is simple and efficient.

Advantageously, the suction nozzles end at a higher level than the level of the blade edge that is intended to bear against the floor. Then there is no risk that the suction nozzle will be exposed to wear together with the blades and will have to be replaced with them.

Preferably, the ring with the suction nozzles and the blades is suspended resiliently in relation to the brush, in such a way that an automatic adaptation of the blade contact with the floor is obtained irrespective of the grade of wear of the brush. Then, the resilient suspension suitably includes three leaf springs, which as an example consist of

flat rods of spring steel having a thickness on the order of 2 mm and extend radially outwards from a hub for the rotation of the brush and the ring. Further, it is suitable that under each leaf spring there extends a flexible pipe or slightly rigid hose from the hub to each suction nozzle, that the hub is hollow for combining the waste water flows from the suction nozzles, and that the pipes or hoses and the leaf springs are dimensioned so as to give an automatic adaptation of the of the blade contact with the floor irrespective of the degree of wear of the brush.

A special advantage is obtained if the water suction device includes a waste water tank for receiving the waste water sucked up, as there in the waste water tank preferably may be located a fresh water bag, which will shrink in volume as the fresh water is consumed by being fed to the brush, so that there will be room in the tank for the sucked up water. In this way, the machine does not require two tanks, and it will be less awkward and handier to work with.

BRIEF DESCRIPTION OF THE ATTACHED DRAWINGS

In the following, the invention will be described in more detail with reference to preferred embodiments and the appended drawings.

Fig. 1 is a perspective view of a combined wet scrubbing machine, which under a hood has a preferred embodiment of the water suction device of the invention.

Fig. 2 is a view from below of the combined wet scrubbing machine of Fig. 1 and shows inter alia the rotatable brush surrounded by a ring provided with a plurality of angularly positioned scraping blades and suction nozzles for the water scraped together.

Fig. 3 is an enlarged perspective view of a ring edge with two different scraper blades and suction nozzle and a portion of a brush located inside thereof.

Fig. 4 is a vertical cross-sectional view of the proper wet scrubbing head and shows the rotatable brush and adjacent components of the water suction device.

Fig. 5 is a perspective view of the components comprised in the water suction device, except for a suction pump with drive motor.

Fig. 6 is a perspective view, partly in vertical cross section, of the main components of the water suction device of Figs. 1 and 2.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS In Fig. 1 there is shown a combined wet scrubbing machine 1 having a low height, which makes it easy for the machine to come in under tables, hospital beds, and the like for cleaning of floors under such furniture without requiring that the furniture be moved. At its rear end, the machine has a rear pair 2 of comparatively large wheels and somewhat further ahead a pair of freely pivotable, self-adjusting swiveling castors 3, which permit movement and turning of the machine by means of a handle 4. In the front end of the machine, there is a rotatable disk-shaped brush 6, which is intended to bear against the floor that is to be cleaned, and a ring 10 that surrounds the brush and is rotatable with the brush. The rotatable disk-shaped brush 6 is driven by V-belts 7 from a motor 9 provided with a bevel gearing 8. On top of the drive motor 9, a fresh water pump 29 is placed. It takes its water from a bag, not shown, or similar flexible container provided inside the waste water tank 25 and feeds the fresh water from a at the end of the horizontal stationary pipe 23 wherefrom the fresh water is fed to the centre of the brush 6 as described in relation to Fi - ¹ gO 4.

When the bag at the beginning is full of fresh water, it fills substantially the entire waste water tank 25, but as the fresh water is being consumed, the volume of the bag is reduced, and room for receiving the sucked up waste water is created in the waste water tank 25. In this way, the machine does not require two tanks, and it becomes less awkward and handier to work with.

Tubes/hoses 17 for transport of waste water to the pipe 23 are shown. The pipe 23 extends backwards in the machine, and via an intermediate hose 24 it conducts waste water to the waste water tank 25. Suction action for the waste water is provided by a suction pump unit 27 connected to the tank 25 and comprising both pump and motor, and the sound from the suction pump is muffled by a sound-absorbing silencer 28.

Suction pump unit 27 and silencer 28 are located beside the drive motor 9 for brush 6 10.

The tubes/hoses 17 are provided with spring leaves 26. Further, by the rotatable ring 10 you can see a plurality of angularly set blades 12, 13 that are attached to the ring 10 and intended to bear slidingly against the floor to scrape together the waste water in a

direction from the outer edge of ring 10 towards its inner edge. In a complete machine, the front end of the machine is covered by a protecting hood 5, not shown in Fig.1.

In Fig. 2, the machine is viewed from below. The V-ropes 7 and the motor 9 are hidden and, consequently, are indicated in dashed lines. For the supply of fresh water and detergent at the center of the brush 6 there are special devices, of which Fig. 2 illustrates a feed pipe 14 arranged coaxially with the brush. Brush 6 is a circular standard brush having a center zone that is free from bristles, and such a brush is available from several different manufacturers, e.g. a brush having article number WR300P from Clean Part AB. In a brush for normal to easy cleaning of most floor surfaces, the bristles have a diameter of about 0.6-0.9 mm and consist of polypropylene, while bristles of nylon and unchanged diameter are preferred for floors of stone, ceramics, vinyl and linoleum. For heavy cleaning of very dirty surfaces and oily floors, nylon fibers having a thickness of 1.2-1.5 mm and impregnated with grit may be used. Also other fiber materials well known to a skilled art worker and in suitable thicknesses may be used.

Ring 10 is provided with on one hand a plurality of suction nozzles 11 rotation- symmetrically placed on the ring for sucking up waste water, and on the other hand the plurality of likewise rotation-symmetrically placed angularly set blades 12, 13 intended to bear slidingly against the floor to scrape together the waste water in the direction from an outer edge to an inner edge, so that it may be removed through the suction nozzles 11. Blades 12, 13 may have a thickness of about 4 mm, for example, and to withstand wear against the floor, it is suitable that they consist of polyurethane, for example.

As shown in Fig. 2, the number of suction nozzles 11 in the water suction device in accordance with the preferred embodiment is three. Further, it is clearly shown that the blades 12, 13 are of two kinds. Blades 13, which are located by the suction nozzles 11, are completely bent backwards at their rear end in the direction of rotation, so that the blades 13 become J-shaped, and the backwards bent rear ends surround the suction nozzles 11 to catch the waste water. By contrast therewith, blades 12, which are located between the suction nozzles 11, are substantially straight. More precisely, as is evident from Fig.2, the blades 12 preferably are slightly bent to an arcuate shape inwardly towards the brush 6, and all of the blades, conveniently nine arcuate blades 12 and three J-shaped blades 13, suitably have such a length in the direction of rotation, that each of them covers a rotational angle on the order of 30°.

Fig. 3 is a perspective view that on a larger scale shows a portion of the annular brush 6, the surrounding ring 10 with a suction nozzle 11 and blades 12 and 13, and outside thereof the hood 5. The rear end of the J- shaped blade 13 surrounds the suction nozzle 11 to an extent that is sufficient for the water that has been collected in the backwards bent rear portion of the blade to be sucked into the suction nozzle 11. In order not to slow down the sucking dry of the collected water, it is suitable that suction nozzle 11 does not go down to the blade edge that is intended to bear against the floor but ends at a higher level. Further, it is clearly shown in Fig. 3 that ring 10 advantageously is split axially into an upper ring member 10a and a lower ring member 10b. Blades 12, 13 extend through apertures in the lower member 10b and have base portions 12a and 13a, respectively, above the lower member 10b, and means, which as an example may be formed by screws 16 that from the top surface of the upper ring member 10a are screwed into the lower ring member 10b, are provided for holding the upper member 10a against the lower member 10b while clamping the base portions 12a, 13a.

Fig. 4 is a vertical cross-sectional view of the proper wet scrubbing head in the machine and shows the rotatable brush and adjacent components in the water suction device. The annular brush 6 is surrounded by the ring 10, which has an upper ring member 10a and a lower ring member 10b, between which the base portions 12a and 13a of blades 12 and 13, respectively, are clamped by means of screws 16. Through the ring members 10a and 10b, the three suction nozzles 11 extend, one of which is shown. Via an individual flexible pipe or slightly rigid hose 17, the upper end of each of the suction nozzles 11 is connected to a tubular hub 18, and the water scraped together by the J-shaped blades 13 is conducted through the suction nozzles 11 and the pipes/hoses 17 to the hub 18. A suitable rigidity is obtained if the pipe/hose 17 has an outer diameter of about 23 mm and a thickness of about 3.5 mm and consists of EPDM rubber.

At its upper end, the hub 18 is rotationally carried in the machine by means of a radial bearing 20, and at the top it has a belt pulley 19 that is driven from motor 9 by means of V-belts 7. Below the belt pulley, an axial bearing 21 is located, which prevents hub 18 from moving upwards and downwards. Brush 6 is directly or indirectly anchored to the hub 18, e.g. by means of screws 22 (vide Fig. 6), and the pipes/hoses 17 transmit the rotation of the hub 18 to ring 10. At the upper end of the hub 18, the horizontal stationary pipe 23 is provided, which is in fluid communication with the rotatable tubular hub, so that the water can pass from the hub 18 to pipe 23. Pipe 23 extends backwards in the machine and via an intermediate hose it conducts the water to a waste water tank. The intermediate hose 24 and the tank 25 are shown in Fig. 5 and Fig. 1. For

an optimal flow of the waste water, the flow area inside the horizontal stationary pipe 23 and in the hub 18 should be equal to the combined flow area of the hoses/pipes 17. In addition, if desired, the attachment of the hoses/pipes 17 to the hub 18 may be somewhat displaced backwards in the direction of rotation. Hereby, the outwardly directed force that the water in the pipes/hoses 17 is subjected to due to the rotation will be reduced, so that the waste water more easily can enter the hub 18 and be drawn off therefrom. The forward end of pipe 23 is closed and provided with a hose nipple 15 for supplying fresh water to the supply pipe 14 arranged coaxially with hub 18 and brush 6. Together the supply pipe 14 and the hose nipple 15 form means for feeding fresh water and detergent in the center of the brush 6, i.e. the fresh water pump 29 pumps fresh water from the bag in the waste water tank 25 (see Fig. 1) via hoses to nipple 15 supplying fresh water to the vertical pipe 14 down through the hub 18 to the center of the brush 6.

The ring 10 with the suction nozzles 11 and the blades 12, 13 preferably is suspended resiliently in relation to the brush 6, in such a way that an automatic adaptation of the contact of the blades 12, 13 with the floor is obtained irrespective of the grade of wear of the brush 6. The resilient suspension, which is best shown in Fig. 5, in addition to the pipes/hoses 17 includes three leaf springs 26, which extend radially outwards from the hub 18. Each of the leaf springs 26 is located directly on top of an associated flexible pipe or slightly rigid hose 17 from the hub 18 to the suction nozzles 11, and the pipes/hoses 17 and the leaf springs 26 are so dimensioned, that an automatic adaptation of the contact of the blades 12 and 13 against the floor is obtained irrespective of the grade of wear of the brush. Suitably, the leaf springs consist of flat rods 26 of spring steel having a thickness on the order of 2 mm. The leaf springs 26 and the pipes/hoses 17 are arranged to move together, which as an example may be achieved by mounting cable ties around the pipes/hoses 17 and the leaf springs 26. In an embodiment not shown, the pipes/hoses 17 are provided with a separate channel for the leaf springs 26.

The perspective view in Fig. 6 shows the water suction device and the brush partly in vertical section. You can see the rotatable tubular hub 18, on which the brush 6 is attached by means of screws 22. The hub also carries the upper ring member 10a and the lower ring member 10b, which together form the axially split ring 10, and which between themselves clamps the base portions 12a and 13a of blades 12 and 13, respectively, by tightening of screws 16. Blades 13 are J-shaped and at their rear end in the direction of rotation each of them surrounds a suction nozzle 11. On the top side of the ring, a hose/pipe 17 connects suction nozzle 11 to the tubular hub 18, the upper end

of which is in fluid commumcation with the horizontal pipe 23, which via an intermediate hose, not shown, leads to the waste water tank 25, so that the suction nozzles 11 are in fluid communication with the tank 25. Sucking action is effected by a suction pump unit 27 connected to the tank 25 and including both pump and motor, and the sound from the suction pmnp is muffled by a sound-absorbing silencer 28. The auction pump unit 27 and the silencer 28 are located beside the drive motor 9 for the brush 6 and the ring 10.

As a matter of course, the invention is not restricted to the above exemplary embodiment but may be varied wimin the scope defined by the claims, For example, the number of suction nozzles may be more than three in number, even though it is advantageous from a cost and material point of view to reduce the number of suction nozzles and associated hoses/pipes.