BRUSH PRESSURE SYSTEM

Abstract: A brush pressure control system for a cleaning, sweeping or scrubbing machine comprising a machine frame supporting a brush head (8), an actuator (10) for raising and lowering the brush head, mounted between the frame and the brush head, an elongate balance beam (32) pivotally connected to the frame (30) and connected at one end to the actuator for movement therewith, and at the other end having a counterbalance mass (35) mounted thereon. The pressure control system (24) is particularly useful for a pedestrian operated machine but may be applied to a ride-on machine too. The improvement allows the system to operate more effectively particularly over low ranges of pressure such as that corresponding to the weight of the brush head itself and it allows for a floating head system over a wide range or pressures. The counterbalance mass (35) is advantageously equivalent to the mass of the brush head (8) and a parallelogram linkage (38) may be provided between the frame and the brush head to keep the brush head generally horizontally positioned. A potentiometer may register the movement of the balance beam as the brush head is raised or lowered so as to provide an indication of brush wear.

Description: BRITS- PRESSURE SYSTEM )F.ς(-"I?TION The present invention relates to a brush pressure system for a cleaning or sweeping machine particularly such as is used for cleaning or sweeping the floor space of commercial and industrial premises or for example supermarket floors or railway station or airport concourses . Such machines may be so-called pedestrian operated, i.e. Controlled by a pedestrian operator or alternatively may be ride- on machines . They comprise rotating brush heads and traditionally the operator is unable to choose the pressure to be applied to the floor by the brush heads: the pressure is set by the geometry of the machine in manufacture or in servicing. The applicant recently invented a control system for such machines and also a floating head system therefor and these are described in publication number 095/13737 the subject matter of which is incorporated herein by reference. The applicant has now developed a substantial improvement to the ccntrol systsem which allows it to operate more effectively, particularly over low ranges of pressures such as around and below the pressure corresponding to the weight of the brush head itself, and to provide an effective and efficient suspension system which allows for a floating head system over a wide range of pressures. According to the present invention there is provided a brush pressure ccntrol system for a cleaning, sweeping or scrubbing machine comprising a machine frame supporting: a brush head, an actuator for raising and lowering the brush head, mounted between the frame and the brush head, a balance beam pivotally connected to the frame and connected at one end to the actuator for movement therewith, and at the other end having a counterbalance mass mounted thereon. The counterbalance mass is advantageously equivalent to the mass of the brush head. Preferably a linkage is provided between the frame and the brush head, and this may be a parallelogram linkage, to keep the brush head suitably and horizontally positioned. According to a preferred embodiment there is also provided means for measuring the wear of the brushes of the brush head and for displaying the wear on an operator console. Such means may comprise a potentiometer registering the amount of movement of the balance arm as the actuator raises or lowers the brush head. The potentiometer registers this change as a change in electrical resistance and this is related tc the brush wear. Typically brushes have a bristle length of 2 inches (4.8cm) when new and can operate effectively even when the bristle length is worn down to only A inch (1.2cm) . The preferred embodiment also provides for a control circuit which is arranged to momentarily pause the actuator at the time at which load sensors register a positive pressure on the brush head, i.e. when the brushes touch the floor. The circuitry measures the position of the potentiometer during this pause and compares it with the previously measured value stored in the circuit and/or to the value measured or preset when the brushes were new, i.e. with calibration values. Electronics such as a microprocessor then uses this information to calculate the relative wear on the brushes and to display the information on a display on the control panel of the machine, e.g. an LED display which may show brush wear as a percentage of either original or remaining bristle length, or indicate a value calculated as corresponding to the actual remaining bristle length or simply provide a high, medium or low indication. At a particularly low value the indicator can be made to flash. These measurements and calculations may be initiated at periodic intervals during use of the machine or might be set only when the brushes are lowered from a raised position. For a better understanding of the present invention and to show how the same may be carried into effect, reference will now be made by way of example to the accompanying drawings in which: Figure 1 shows a cross-section elevational view of a brush assembly for a cleaning and sweeping machine in front view. Figure 2 is a perspective view of a cleaning and sweeping machine incorporating a brush pressure assembly according to the applicant's previous invention; Figure 3 is a diagrammatic representation of a control for the apparatus of Figures 1 and 2; and Figure 4 is a side view of the brush pressure assembly of Figure 1 showing the control system of the present invention. In Figure 1, the brush assembly comprises two spring tubes 1, containing springs 2. The right hand tube 1 in the Figure is shown in cut-away to illustrate spring 2. Each spring is fixed at one end to the upper end of the tubes at 3 and at the other end to a spring rod 4 which slides through an aperture 5 into the respective spring tube 1. The spring rods 4 are connected together by a bolt 6 and are fixed via assembly 7 to the brush support plate 8 to which brush head or heads 27 are connected. The tubes 1 are prevented from rotating or skewing by a steadying plate 9. An actuator 10 is secured to a bulkhead of a cleaning machine. Actuator 10 drives actuator rod 12 which is snown m substantially closed up position in the Figure. The actuator rod 12 is fixed by a pin 13 to actuator plate 14 which is clamped to both spring tubes 1 by clamping bolts 15. Thus as the actuator drives the actuator rod 12 downwards, the spring tubes 1 move downwards and the springs 2 are compressed causing a higher pressure to be exerted on the brush head assembly whilst still providing suspension to accommodate uneven floors and brush wear. Typically, the effective spring lengths, in an uncompressed state, are around 15 inches and this is particularly suitable for a 26/32 inch brush pressure system. Such an arrangement can provide a range of 0 to 4501b pressure in a loaded pedestrian cleaning machine fitted with apparatus according to the invention, compared to the maximum 2001b pressure available using known apparatus . Of course other forms of biasing means could be used. A torsion spring has the advantage of taking up less vertical space in a cleaning machine. Also, a torsion spring generally has a low spring rate which is particularly suitable for this purpose. Gas struts or hydraulic or pneumatic systems could also be used. The pressure can be further adjusted by changing the springs for different length ones or different strengths the clamping position of the spring tubes can be altered. However these changes require a service engineer. The system is particularly adjustable since the actuator can be stopped anywhere in its stroke. Usually brush support plate 8 will be attached to a pair of circular or elliptical brushes rotating in a plane generally parallel to the floor (or surface to be cleaned or swept or scrubbed) . However, up to four brushes are in use in some cleaning machines and the apparatus of the invention could be used to control all such four brushes together or alternatively individually (in which case separate actuators would be used for each) . Of course a cylindrical brush head could equally easily be controlled mounted on the brush support plate 8 or alternatively controlled at each end of its shaft by respective separate assemblies according to Figure 1. A strain gauged beam 20 which may be used to measure the crush pressure s located under the spring tube clamp plate 18. In Figure 2 the brush assembly of Figure 1 is shown mounted m a pedestrian cleaning apparatus. Like parts are indicated by like reference numerals and a pair of spring tubes 1 are attached to actuator rod 12 by actuator plate 14. The actuator 10 is fixed by t e bar 15 to the apparatus frame 16. A second pivoted mounting 17 connects the assembly 7 and brush support plate 8 to frame 16. The brushes themselves are not shown in Figure 2 but are mounted below the support plate 8 behind the protective flange 17 and are driven by scrub brush motors 18 (one of which is shown in Figure 2) . Figure 2 also illustrates the relative positions of the water tank or tanks 19, the batter pack 20 for driving the scrub motors 13 together with the transverse drive of the cleaning apparatus. The direction of transverse drive is controlled by a handle 21. A squeegee 22 has suction applied via vacuum motor 23. Additionally a brush head pressure control panel 24 is provided withm the operator's view. In Figure 3 the brush assembly is shown schematically in side view and a control system is illustrated as a block diagram. The position of the brush head 27 relative to the floor to be cleaned, is controlled by electric or hydraulic actuator 10 lifting or lowering the brush head via an actuator rod which compresses springs m spring tube 1. Other resilient means such as a gas strut may be used for applying pressure to the brush head against the floor and of course other means may be used to control the position of the brush head such as hydraulic or pneumatic means. Details of the actuator 10 has been described above. A pressure sensor is located at one of the positions labelled 4 though it may be positioned anywhere in the cylinder or in the arm or in the bottom of the actuator. In use this sensor monitors the pressure applied by the brush to the floor and generates a signal 25. The pressure sensor may be a strain gauge 20 on actuator plate 14 as shown in Figure 1 or a piezoelectric sensor or position sensor. Alternatively the secure pin (11 in Figure 1) which connects the assembly to the apparatus frame, may be used as a shear gauge to measure pressure. Amplifier 26 converts this pressure signal 25 to a value usable in the subsequent circuitry. The control panel 24 is provided within sight of an operator. It has a pressure select knob 28 by which the operator can pre-select a particular pressure. A rocker switch 29 lifts or lowers the brush head 27 relative co the floor depending on the switch position. A digital display 30 illustrates the pressure of the brush head 27 cn the floor, as measured by the pressure sensor. A processor 31 compares the measured pressure signal with the operator selected pressure and generates a control signal accordingly to control (as necessary) the actuator to make the measured pressure substantially the same as the selected pressure . This processor may be of simple construction such as comprising an electronic comparator and amplifier circuit, or it may comprise a standard CPU unit in chip form. Power for the electronic components is supplied by the on¬ board battery 12 or by alternative low power battery sources. Figure 4 shows the brush head with planetary brushes for scrubbing, cleaning, polishing or sweeping a floor surface mounted via the actuator 10 (only one arm of which is shown) to the machine frame, specifically to the actuator support bracket 30. The brush head is raised and lowered as indicated by arrow 31 by a screw jack-mounted on the actuator 10. The motors for driving the brushes are mounted on the brush head but are not shown in Figure 3. The water tanks for the machine, mounted on the frame, or chassis are also omitted in Figure 3 to more clearly show the other parts of the device. A balance beam 32 is mounted by pivot bearing 33 to one end of a pivot support 34, the other end of which is connected to the frame. The beam 32 is also connected to actuator arm 1 and on the other side of the pivot bearing 33 to a counterweight 35 corresponding to the weight of the brush head. The opposite end of beam 32 is linked to the brush head by a turnbuckle linkage adjuster 36, which is used to adjust the counterbalance for brushes of different length, for example to prevent jamming of the brushes against the floor. A potentiometer 37 for measuring brush wear is connected between the balance beam 32 and the pivot support 34. Further support for the brush head is provided by a parallelogram linkage 38 between the brush head and the side of the main frame to keep the brush deck positioned. A drive wheel 39 for the machine is shown: usually one such wheel is positioned at each corner of the chassis or frame. The path of movement of the counterweight is shown in dotted outline, as the brushes are raised by the lower line and as they are lowered by the upper line. As the brushes are lowered to the floor bv the actuator 10 the balance beam 32 rotates about Divot bearing 33 and the counterweight 35 swings upwardly. The change in position of the balance beam 32 causes a corresponding change in the position of the wiper of the potentiometer and 37 thus the measured resistance changes. A load sensor (not shown in Figure 4) detects the position at which the brushes touch the floor, i.e. a positive pressure is registered and pauses the actuator momentarily for the potentiometer measurement at that position to be recorded. The actuator then continues to drive the brush head down onto the floor until the desired pressure on the floor is attained. The counterweight counteracts the weight of the brush head and allows a very low range of brush pressures to be selected, much lower than was hitherto attainable, for example less than 1001bs/in 2 . This range is used for light cleaning or polishing or for cleaning fragile or specialist floor surfaces. Comparison of readings on the potentiometer as the brushes contact the floor is a measure of the amount of wear on the brushes and can be used to provide an indication of such on a display panel of the operator's console. This example is of course only one of many possible embodiments of the invention. It will readily be understood by a person skilled in the art that this system is applicable to cleaning, sweeping, polishing and scrubbing machines of a wide variety of types and could be used on machines needing to apply pressure not only downwards but upwards, and sidewards too with suitable modifications which are within the non-inventive capabilities of a person skilled in the art.

Claims: CLAIMS : 1. A brush pressure control system for a cleaning, sweeping or scrubbing machine comprising a machine frame supporting a brush head, an actuator for raising and lowering the brush head, mounted between the frame and the brush head, an elongate balance beam pivotally connected to the frame and connected at one end to the actuator for movement therewith, and at the other end having a counterbalance mounted thereon. 2. A brush pressure control system according to claim 1 wherein the counterbalance has a mass which is substantially equivalent to the mass of the brush head. 3. A brush pressure control system according to claim 1 or claim 2 further comprising a linkage connecting the frame and the brush head in such a manner that the brush head is substantially horizontally supported. 4. A brush pressure control system according to claim 3 wherein the linkage is in the form of a parallelogram linkage. 5. A brush pressure control system according to any preceding claim further comprising measuring means for measuring the wear of a brush supported on the brush head and displaying means for displaying the measured wear on an ooerator console. 6. A brush pressure control system according to claim 5 wherein the said measuring means comprises a potentiometer for sensing the amount of movement of the balance beam as the actuator is used to raise or lower the brush head. 7. A brush pressure control system according to any preceding claim further comprising a load sensor for registering when a positive pressure is applied to the brush head and means to pause the actuator when the load sensor registers such a positive pressure. 8. A brush pressure control system according to comprising means to calculate the relative wear on the brushes and means to display the relative wear. . A brush pressure control system substantially as herein before described with reference to the accompanying drawings.

Inventors: BRISCOE WILLIAM ANTHONY, BRISCOE, WILLIAM, ANTHONY
Applicants: BRISCOE WILLIAM ANTHONY, BRISCOE, WILLIAM, ANTHONY
Application year: 1996
Main classification: A47L11
IPC codes: A47L11