FLOOR CLEANING MACHINE WITH IMPROVED BRUSH PRESSURE CONTROL

Abstract: An automatic floor-leaning and floor-treating machine having improved brush-pressure control, said machine comprising a body (1) which is supported on wheels (2, 3) and one or more rotating brushes (4), said brushes (4) being mounted on one side of a frame (5) which can be pivoted relative to the body, the other side of the frame beyond the center of rotation being connected to one end of a spring (6), the other end of which can be displaced by means of a motor, characterized in that there is provided a second spring (9) which is connected at one end to the displaceable end of the first spring (6), and at the other end to the frame at the side where the rotating brushes are mounted. Preferably, the attachment site of the first spring (6) to the second spring (9) is connected to the actuator arm (7) of a servomotor (8).

Description: The present invention relates to a floor-cleaning machine and in particular to an automatic floor-cleaning and -treating machine which can be used for cleaning carpets and hard surfaces of large floor areas, such as in hotels, factories, office buildings, shopping centers and the like. Such a floor cleaning machine is known in the art and is for instance described in the German patent application 2,153,518. This document discloses an adjustable device suitable for use in floor-cleaning machines comprising rotating brushes and for obtaining variable brush pressure control in such machines. Another floor-cleaning machine with variable brush pressure control is described in the European patent application 173,394, which is considered to be the closest prior art. It comprises a body which is supported on wheels and two rotating brushes which are driven by an electrical motor. The body contains reservoirs for storing fresh and spent cleaning liquid, means for dosing fresh cleaning liquid on to the floor and a battery, pump and motor. The machine is moved around by means of two electrically driven wheels in front and steered by means of one or more steering wheels at the rear. The rotatable brushes are mounted on one end of a pivotable frame. The other side of the frame, beyond the center of rotation, is connected to one end of a spring, which is extendable by means of a motor. The brush pressure on the floor is proportional to the spring tension and can thus be varied by actuating the motor. It is important that the brush pressure on to the floor can be regulated or varied, because various types of floors and floors having different amounts of soil would require a different approach. For instance, a large brush pressure on a lightly soiled floor would cause excessive wear of the floor and of the brushes and other machine parts, while it would also lead to an excessive energy consumption as a result of the large frictional forces. On the other band, if the brush pressure is too light, unacceptable cleaning results may be obtained on heavily soiled surfaces. We have now found that an improved variable brush pressure control can be provided by the floor-cleaning and floor-treating machine according to the present invention, which is characterized in that there is provided a second spring which is connected at one end to the displaceable end of the first spring, and at the other end to the frame where the rotating brushes are mounted. Preferably, the attachment site of the first spring to the second spring is connected to the actuator arm of a servomotor. In an especially preferred embodiment, the actuator arm of the servomotor near its fully extended position runs up with the frame, such that upon further extending the actuator arm the frame will be pivoted and the rotating brushes will be lifted off the floor. The invention will now be explained in detail by means of the following specific descriptions in which: Figure 1 schematically illustrates as a preferred embodiment of the invention a detail of a floor-cleaning and -treating machine having its rotating brushes lifted off the floor; Figure 2 illustrates the same machine with its brushes lowered on to the floor under a light downward pressure; Figure 3 illustrates the same machine with its brushes lowered on to the floor under a medium downward pressure; and Figure 4 illustrates the same machine with its brushes lowered on to the floor under a high downward pressure. Figure 1 shows a detail of a floor-cleaning and -treating machine according to the invention in a schematical way. For the sake of clarity, only the vital parts are depicted; the body, the reservoirs, etc. are not shown. The figure does show the main driving wheels 2 and the steering wheels 3 on which the body 1 of the floor-cleaning machine is supported, and a rotating brush 4 which is mounted on a frame 5. This frame can be pivoted relative to the body of the machine upon an axis 10, which in the depicted situation coincides with the central axis of the two main driving wheels 2. The other side of the frame, i.e. the side where the brushes are not mounted, is connected to one end of a tension spring 6. The other end of the spring 6 is connected to an actuator arm 7 of a servomotor 8, which is attached to the body of the floor-cleaning machine. The actuator arm 7 of the servomotor is also connected to a second tension spring 9. This second spring is connected at its other end to the frame, near the place where the rotating brushes are mounted on the frame. In Figure 1, the actuator arm of the servomotor is shown in its fully extended position. It has run up with the frame and has pushed it away, thereby pivoting it around the center of rotation 10. The rotating brushes 4 have thereby been lifted off the floor. The tension in the first spring is now minimal; in the second spring it is maximal. When the servomotor is now operated, the actuator arm 7 is gradually retracted (Figures 2-4). First, the frame will be pivoted until the brushes just come into contact with the floor. At that stage, the downward pressure of the rotating brushes on the floor will be negligible and the cleaning action will be minimal. Upon further retracting the actuator arm, the first spring will now be stretched while the second spring will be relaxed. The resultant down-pressure of the brushes on the floor, which equals the vertical component of the vector summation of the tension forces in the two springs, is thereby gradually increased until a maximal value is reached (see Figure 4). By way of example, some numerical data on the tension strength in the respective springs are also given in the figures. It can be seen that, owing to this construction, the down-pressure of the rotating brushes can be easily varied and regulated over a broad range, which is determined by the dimensions and relative orientations of the respective springs. This means that a flexible approach is offered to the different situations encountered in floor cleaning, each requiring a different optimal brush pressure. According to the present invention, the downward brush pressure can be particularly well regulated in the range between zero pressure and the weight exerted by the mass of the brush assembly. The motor for lifting the brushes off the floor only needs to cope with the difference between the tension in the first and the second spring and can accordingly be dimensioned smaller than in the known floor-cleaning machines which have only one spring. Thus an important economical advantage is achieved in the manufacturing of the floor-cleaning machines according to the invention. It will be understood that instead of the two tension springs 6 and 9 shown in Figure 1, also a combination of two or more identical or different spring means can be envisaged, without departing from the scope of the present invention. The servomotor 8 to be used according to the present invention can be any type of known servomotor which translates a given input signal, such as an electrical signal, into a preferably linear displacement of its actuator arm. The servomotor 8 can be operated from the control panel by means of a suitable conventional controlling circuit. It can also be controlled by a feed-back circuit in which the current is measured through the main motor driving the rotational brushes, using a preset value which is entered at the control panel.

Claims: Automatic floor-cleaning and floor-treating machine comprising a body (1) which is supported on wheels (2,3) and one or more rotating brushes (4), said brushes (4) being mounted on one side of a frame (5) which can be pivoted relative to the body, the other side of the frame beyond an axis (10) about which said frame (5) is pivotable relative to the body (1) being connected to one end of a spring (6), the other end of which can be displaced by means of a motor, characterized in that there is provided a second spring (9) which is connected at one end to the displaceable end of the first spring (6), and at the other end to the frame at the side where the rotating brushes are mounted. Automatic floor-cleaning machine according to claim 1, wherein the attachment site of the first spring (6) to the second spring (9) is connected to the actuator arm (7) of a servomotor (8). Automatic floor-cleaning machine according to claim 2, wherein the actuator arm (7) of the servomotor (8) near its fully extended position runs up with the frame, such that upon further extending the actuator arm the frame (5) will be pivoted and the rotating brushes (4) will be lifted off the floor.

Inventors: HUPPI, KARL
Applicants: UNILEVER N.V., UNILEVER PLC
Application year: 1990
Main classification: A47L11
IPC codes: A47L11, E01H1