TECHNICAL FIELD The invention described herein relates to apparatus for cleaning floors, and especially carpeted floors, of the type that applies a fluid such as steam or a detergent solution to the floor and also applies suction to the floor, and to methods for cleaning floors, especially carpeted floors. BACKGROUND ART Equipment is known for using vacuum and a fluid for the cleaning of carpets and other floor coverings. Such equipment generally has a vacuum nozzle (also known as a vacuum head) which is moved across the carpet surface to lift dirt therefrom and, in addition, means for applying a fluid to the carpet surface. The vacuum nozzle may also lift the fluid from the floor after application of the fluid. Generally, the vacuum nozzle and fluid application means are moved back and forth manually by a user of the equipment. In some devices, the vacuum nozzle and fluid application means are incorporated in a hand-held wand, connected by vacuum and fluid hoses to separate vacuum and fluid supply means. A user of such a device moves the wand back and forth over an area of the floor surface to be cleaned. Over time, such work is fatiguing and unpleasant. A given part of a carpet surface must generally be traversed several times for a satisfactory cleaning result to be obtained.

In other machines, the vacuum head and fluid application means are incorporated in a wheeled unit that also contains the vacuum and/or fluid supply means. These machines too are often found to be fatiguing to use.

The effort required of users of such equipment is found in practice to be such as to place a limit on production rate, i.e. the area of carpet that can

be cleaned in a given time, or at least on the consistency of the production rate.

Some attempts at improvement have involved the use of vacuum heads that are moved by the machine itself, so limiting the need for repetitive back-and-forth movement of a wand. In a motorized machine known to be available on the market, counter rotating vacuum heads are used. These are regarded as providing an inferior clean, inasmuch as their action is harsh and the machine has the ability to lay the pile in one direction only during the cleaning cycle. It has been found desirable to first lay the pile of carpet in one direction and then lay it it in the opposite direction, as is usual in equipment having a manually moved wand.

Other machines provide a reciprocating movement of one or more vacuum heads and fluid application nozzles - see for example the published specifications of US Patents 4095309 and 5867860, the contents of both of which are here incorporated by reference. These machines appear to have operating mechanisms that make provision of long nozzle stroke lengths difficult. Some at least also appear to use high speeds of the nozzles on the floor. Resulting control and vibration problems have been noted.

Moreover other reciprocating head machines have reciprocating mechanisms that provide sinusoidal or similar motion of the nozzle, leading to the possibility of uneven application of cleaning fluid and vacuum.

Floor and especially carpeted floor cleaning equipment may use any of several types of fluid. Examples are steam, hot water (usually with a surfactant such as a detergent added), liquid solvents, and chemically reacting mixtures that generate carbon dioxide bubbles to produce a cleaning action. On-off control of the application of such fluids is normally provided by the operation of a switch by a user of the cleaning equipment. Applicant considers that there is a need for better control of the application of such cleaning fluids and has also addressed this problem, in the interests of both economy and better cleaning results.

The inventions disclosed herein address the above problems. It is to be understood throughout this specification that the inventions are applicable to equipment that uses any of the fluids mentioned above, so that any reference to a fluid can be a reference to any of these fluids.

DISCLOSURE OF INVENTION

According to the invention in a first aspect, there is provided carpet cleaning apparatus for use on carpeted and like floor surfaces including: a chassis supported at least partially on wheels and movable on a surface to be cleaned; a vacuum nozzle mounted on said chassis for movement in a direction longitudinal to said chassis and positionable against said surface; and drive means for moving said nozzle repetitively though a movement cycle including a forward movement and a rearward movement, and fluid application means for applying a fluid to the surface to be cleaned, wherein said fluid application means is operable by a user to apply said fluid to said surface during said movement cycle.

Preferably, said drive means is capable of moving said vacuum nozzle at substantially a constant speed for at least a part of said forward movement and for at least a part of said rearward movement. This limits the tendency to treat the surface unevenly.

Said drive means may include: an endless belt or chain running on spaced apart wheels or sprockets that are mounted to said chassis; a first component secured to said belt or chain at a fixed point along the length thereof so as to be moved forward and backward during each complete revolution of a said wheel or sprocket; a second component longitudinally movable on said chassis, said nozzle being arranged to follow longitudinal movement of said second component on said chassis; connection means whereby longitudinal movement of said first component is transmitted to said second movement.

Said second component may include a carriage movable on longitudinal guide means and to which said vacuum nozzle is mounted. Said connection means includes a connecting member secured to said second component and relative to which connecting member said first component is free to move in a vertical direction, said connecting member being movable longitudinally by said first component.

Preferably, said connection means includes a link connecting said first component and said second component.

Said vacuum nozzle is preferably movable in an at least partially vertical direction with adjustment means being provided on said carriage to provide control of pressure of said vacuum nozzle downward against said carpet to be cleaned.

Said fluid application means may include one or more nozzles able to be placed in fluid communication with a supply of said fluid. It is particularly preferred that said one or more nozzles are movable longitudinally with said vacuum nozzle.

The apparatus may include further fluid application control means that when said supply fluid application means is actuated by a user automatically varies the application of fluid to the surface to be cleaned at least once in the course of each complete cycle of movement of the vacuum nozzle. The apparatus may include switches sensors or the like arranged to be operated at predetermined points in the cycle and in turn to trigger changes in state of a valve controlling flow of fluid within the fluid application means.

The apparatus may further include means whereby different sets of said variations to said application of fluid are selectable by a user, and on selection are executed automatically through each complete cycle of vacuum nozzle movement.

Preferably the apparatus further includes means for driving said apparatus from one position to another across said surface. To this end, there may be included means whereby said wheels are able to be prevented from rotating during a selected one of the forward and rearward parts of the movement cycle and able to be permitted to rotate during the other of the forward and rearward parts of the movement cycle so that said drive means moves said chassis when said wheels are permitted to rotate.

In a further aspect, the invention provides a carpet cleaning method including the steps of: providing a chassis supported at least partially by wheels and movable over a surface to be cleaned;

supporting a vacuum nozzle from a chassis for movement in a direction longitudinal to said chassis and for positioning of said nozzle against said surface; driving said nozzle repetitively though a movement cycle including a forward movement and a rearward movement, providing user operable fluid application means for applying a fluid to the surface to be cleaned; and during said movement cycle actuating said fluid application means to apply fluid to said surface to be cleaned. It is preferred that said vacuum nozzle is moved at substantially a constant speed for at least a part of said forward movement and for at least a part of said rearward movement.

Preferably, when said fluid application means is actuated the application of fluid delivered by fluid application means from a fluid supply to the surface to be cleaned is automatically varied at least once in the course of each complete cycle of movement of the vacuum nozzle.

The method may include the step of moving said chassis and said nozzle between successive operating positions on said surface to be cleaned by actuation of drive means mounted on said chassis. This may be done by moving said chassis between said successive operating positions by preventing rotation of said wheels during a selected one of the forward and rearward parts of said movement cycle and permitting wheel rotation during the other of the forward and rearward parts of said movement cycle. BRIEF DESCRIPTION OF DRAWINGS In order that the invention may be better understood there will now be described, non-limitingly, a preferred embodiment as shown in the attached Figures, of which:

Figure 1 is a side view of a cleaning device embodying the invention;

Figure 2 is a plan view of the cleaning device of Figure 1 , with a cover and handle removed and certain hoses omitted for clarity;

Figure 3 is a cross-sectional view of the device as shown in Figure 2, the section being taken at station 3-3;

Figure 4 is a cross-sectional view of the device as shown in Figure 3, the section being taken at station 4-4;

Figure 5 is a schematic electric circuit diagram of the device shown in Figure 1;

Figure 6 is a schematic diagram of an alternative circuit for the device of Figure 1. BEST MODE FOR CARRYING OUT THE INVENTION

Figures 1 to 4 show a carpet cleaning device 1 that embodies the present inventions. Device 1 includes a chassis 2 supported by rear wheels 3 and a front skid rail 4, so as to be able to be moved as required over a carpeted surface 5 by a user. Chassis 2 is arranged by means set out below to support a vacuum nozzle 6 and fluid nozzles 7 secured to the nozzle 6 in such a way that nozzles 6 and 7 are movable in reciprocating fashion forward and backward in a longitudinal direction shown by arrow 8, with a lower end 9 of nozzle 6 in contact with the carpeted surface 5.

Figure 1 shows device 1 fitted with a protective cover 50 and handle assembly 51 that would be provided in actual use of device 1. In Figures 2 - 4, device 1 is shown for clarity without cover 50 and handle assembly 51. In Figure 2, a vacuum hose 23, a fluid hose 35 and a valve 37, shown in other Figures and described below, have been omitted for clarity.

Nozzle 6 and fluid nozzles 7 are mounted to a longitudinally movable carriage 19 in a manner described below. Chassis 2 has longitudinally extending side rails 17. To each one of rails 17 is secured a longitudinally extending guide rod 18. Carriage 19 is supported on guide rods 18. Carriage 19 is supported by four rollers 52 that are movable along guide rods 18. Rollers 52 are shown in phantom outline in Figure 2, as they are below a top plate 53 of chassis 2 and partly below a plate 54 included in carriage 19. (Linear bearings could be used instead of rollers 52, if preferred.)

Secured to chassis 2 is a motor 49 and gearbox 10 arranged to rotate a sprocket 11 at a speed that is either fixed or that can be selected by a user and that then remains fixed until changed again by the user. Means for making the speed of rotation of sprocket 11 user-controllable are not shown but are well known in the art of machine design. For example motor 49 could be a three-phase AC induction motor powered by a variable frequency controller. An idler sprocket 12 is rotatably supported on a bracket 13 that is also mounted to chassis 2. Mounted on sprockets 11 and 12 is an endless

roller chain 14 having an upper run 15 and a lower run 16 extending between the sprockets 11 and 12. Runs 15 and 16 of chain 14 extend longitudinally, i.e. parallel to arrow 8. The position at which bracket 13 is secured to chassis 2 can be adjusted forwards or rearwards as required to tension chain 14, in known manner.

In use of device 1 , chain 14 moves in one direction only, but carriage 19 is moved backward and forward, i.e. reciprocated, by the movement of chain 14. Included in carriage 19 and secured to plate 54 is an upright support member 20. Pivotally secured to support member 20 is a forward end of an elongate link 21. A rearward end of link 21 is secured pivotally to one link 55 of roller chain 14. Accordingly, as link 55 is carried forward along upper run 15 of chain 14 carriage 19 is moved forward by link 21 , and as link 55 is carried backward along lower run 16 of chain 14 carriage 19 is moved rearwardly by link 21. As link 55 passes around the peripheries of sprockets 11 and 12, link 21 pivots about its attachments to support member 20 and link 55. To enable the above movement of carriage 19, a longitudinal slot 56 is provided in plate 53 of chassis 2. (See Figure 2.)

Vacuum nozzle 6 is secured on a front end of an arm 26 and has an upper end pipe-like section 22 to which is sealingly attached a flexible vacuum hose 23. Hose 23 is sealingly secured at a rear end to a short rigid pipe 31 that in turn is secured to an upright member 30 secured to chassis 2. In use of device 1, pipe 31 is connected to a vacuum-maintaining source (not shown) separate from device 1 so that a partial vacuum is maintained in nozzle 6. At its lower end 9, nozzle 6 has an opening 57 that is narrow in the longitudinal direction 8 and elongate in a direction transverse to the chassis 2. Opening 57 is bounded at its front and rear by nozzle walls 24 and 25 respectively of nozzle 6. Arm 26 has rear end pivots 27 by which it is secured to brackets 76 which depend from plate 54 of carriage 19. Thus, nozzle 6 can rise and fall over any minor undulations in carpeted surface 5, independently of any movement of chassis 2, as it is moved over surface 5. Between arm 26 and chassis 2 is provided a coil spring 28 that is in normal use of device 1 partially compressed and whose length can be adjusted by an adjusting screw 29. By suitable adjustment of spring 28, lower end 9 of nozzle 6 is in use pushed downwardly against carpeted surface 5 with a force found to be suitable for

the particular application. (In a prototype, spring 28 is adjusted to actually reduce the effect of the weight of nozzle 6.) This assists in ensuring that the partial vacuum maintained in nozzle 6 is best used to lift dirt, dust and fluid from carpeted surface 5 and additionally ensures that nozzle walls 24 and 25 push the pile of carpet 5 forward when nozzle 6 is moving forward and rearwardly when it is moving back.

To permit the forward and rearward movement of nozzle 6, a longitudinally elongate slot 58 is provided in top plate 53 of chassis 2.

To enable a user to vary the vacuum in nozzle 6 to a value suitable for the work in hand, pipe 31 has an opening 32 and a sleeve 33 surrounding pipe 31 that can be rotated to uncover opening 32 to varying degrees. By rotating sleeve 33, air leakage into pipe 31 through opening 32 is controlled, and so the vacuum in nozzle 6 is also controlled. Such an arrangement for vacuum control is known in vacuum cleaners, and is not of the essence of the present invention.

Secured to rear wall 25 of nozzle 6 and spaced apart across its width are fluid nozzles 7. By way of a suitable manifold 34, nozzles 7 are connected to a flexible hose 35 that extends to a quick-connect fitting 36 mounted on member 30. In use of device 1 , connector fitting 36 is connected to separate equipment (not shown) that supplies fluid for nozzles 7. A solenoid-operated valve 37 is provided between fitting 36 and manifold 34 to control the spraying of fluid from nozzles 7 onto carpeted surface 5. Hose 35 is of such length as to permit forward and backward movement of nozzle 6, and with it nozzles 7, through stroke length 80 (see Figure 4). Two microswitches 38 and 39 are secured to chassis 2 in positions where they are each triggered once per complete forward-and-backward cycle of movement of nozzle 6. Microswitches 38 and 39 form part of an automatic system for controlling the supply of fluid to nozzles 7. When nozzles 6 and 7 reach the forward end of their travel, front microswitch 38 is triggered by a strike arm 40 on carriage 19. When nozzles 6 and 7 subsequently reach the rear end of their travel, a further strike arm 59 triggers rear microswitch 39. This process is repeated for so long as motor 49 operates. Thus, microswitches 38 and 39 provide for the automatic control of the delivery of fluid through nozzles 7 within each cycle.

Figure 5 is a schematic circuit diagram for device 1. An AC electric power source 70 is connected across two rails 71 and 72, and a master switch 41 is provided in rail 71. Master switch 41 is mounted on handle assembly 51 and spring loaded so as to require squeezing by a user in order for the whole of rail 71 to be energized. A motor controller 73 powered from rails 71 and 72 provides a variable frequency 3-phase output to drive motor 49 at a user-selected speed. Front and rear microswitches 38 and 39 are of the type that conduct only so long as their respective mechanical triggers (not shown) are actuated, by their temporary contact with strike arms 40 and 59 respectively. A relay 74 having normally-closed contacts 76 is operable by rear microswitch 39. A relay 75 having two sets of normally-open contacts 77 and 78 is operable by front microswitch 38. Solenoid valve 37 operates to deliver fluid to nozzles 7 when contacts 78 are closed, provided a "fluid-on" switch 79 has been closed by the user. In use of device 1 , the user closes switch 41 so that motor 49 is operated at a chosen speed. Supposing the user also closes the fluid-on switch 79, the operation is as follows. Front microswitch 38 is triggered momentarily when strike arm 40 reaches its furthest forward position, so that relay 75 is switched on. This closes contacts 77 so that relay 75 stays on, and also closes contacts 78 so that valve 37 permits fluid supply to nozzles 7. This position is maintained until carriage 19 reaches the end of its rearward movement and strike arm 59 momentarily turns relay 74 on. This opens contacts 76, so that relay 75 is de-energized. This opens contacts 77 and 78 so that valve 37 closes off the fluid supply to nozzles 7 and remains closed. When strike arm 40 reaches microswitch 38 again, as carriage 19 reaches its furthest-forward position, the same process is repeated. Thus, fluid is supplied to nozzles 7 only on the rearward stroke of nozzles 6 and 7. Nozzle 6 sucks continuously during the cycle. If switch 79 is opened, no fluid is supplied to nozzles 7 and only vacuuming takes place. If switch 41 is opened, motor 49 stops and fluid delivery is also stopped.

It will be apparent that if microswitch 38 is made the rear one and microswitch 39 is made the front one, fluid will be supplied to nozzles 7 only during forward movement of carriage 19 instead of during rearward movement. It is readily possible to provide the user with a switch to choose

one or the other of these two functionalities. Figure 6 is a schematic diagram of an alternative to the circuit of Figure 5 with this capability. The circuit is identical to that of Figure 5 (and the same item numbers as in Figure 5 are used for equivalent components) except that relay 75 has an additional set of contacts 81 of normally-closed type, and a switch 80 is provided allowing the user to select either these or the normally-open contacts 78. When switch 80 is set to use contacts 78 (as shown) fluid can be supplied to nozzles 7 during their rearward movement. But when switch 80 is set to use contacts 81 nozzles 7 can instead be supplied with fluid during their forward movement. Such a refinement has the advantage that fluid can be directly applied to the pile when it is being bent one way, and then applied when it is being bent the other way.

It will be apparent to persons skilled in the art that alternative means may be used to provide such functionalities as those described above. For example microswitches 38 and 39 could instead be proximity sensors or other suitable sensors of non-contact, non-mechanical type. For further example, a microcontroller or programmable logic controller (PLC) could be used instead of the hard-wired arrangements of Figures 5 and 6. Such equipment is known to persons skilled in the art and need not be described in detail here. The particular cleaning methods defined by the above descriptions of the operation of the circuits of Figures 5 and 6, could themselves be varied, and the more complex microcontroller or PLC particularly lend themselves to doing so.

For example (although not shown), a single microswitch (or other suitable sensor) could be used, to trigger a timer circuit when the nozzles 7 have reached a particular point in their cycle of movement (for example the forward end of their travel) so that valve 37 is operated to deliver fluid for a predetermined period. That period could itself be made adjustable by a user. Still another possibility is to provide multiple microswitches or other sensors to trigger a delivery of fluid for a set period at particular points in the cycle, for example once during forward movement of the vacuum nozzle and once during rearward movement of the nozzle.

It would also be possible to provide an additional set of fluid delivery nozzles, not shown but like nozzles 7, on the front of nozzle 6. By

straightforward control means that could readily be developed by persons skilled in the art, it could be arranged for example that the fluid is supplied to these forward nozzles when the vacuum nozzle 6 is moving forward and the nozzles 7 when nozzle 6 is moving backward, or vice versa. Although nozzles 7 have been shown outside nozzle 6, it is within the scope of the invention to provide nozzles 7 inside nozzle 6, i.e. between walls 24 and 25.

It will be recognized from the above description that many different arrangements for the supply of fluid during each cycle of movement of nozzles 6 and 7 can be provided as required. However, the simple functionalities described above in relation to Figures 5 and 6 are considered to provide good results in many applications.

The use of front skid rail 4 to partly support chassis 2 has been found satisfactory, but is not essential. As a second possible variation, a pair of castoring wheels (not shown) could instead be provided at the front of chassis 2 instead of skid rail 4, given that the nozzles 6 and 7 are reciprocated in a movement similar to scrubbing without any need for the user to move them backward and forward manually. The user needs only to move the machine progressively to new locations on the carpet surface 5, not to apply a scrubbing motion.

It is readily possible to provide an electric motor drive (not shown) for the wheels 3 if required, further reducing the effort required to operate the device 1. Brakes (not shown) could readily be provided for wheels 3, to be applied manually or automatically, on disengagement of such a motor drive, so that any tendency to move due to the reciprocating action of nozzle 6 can be eliminated or at least limited. Another possibility is to drive the wheels 3 with an electric motor and worm gear combination (not shown), with no brakes, as the worm gear would prevent wheel 3 rotation when the motor is de-energized. It is also possible to provide user-operable brakes for wheels 3 without a wheel motor drive at all, so as to exploit the reciprocating action of nozzle 6 for moving the device 1 between locations on a floor. For example, by applying wheel brakes during the forward movement of nozzle 6 and releasing them during rearward movement of nozzle 6, device 1 can be made to move

forward, provided that its resistance to movement is less than the force exerted by nozzle 6 on floor surface 5. Conversely, applying the wheel brakes during rearward movement of nozzle 6 and releasing them during forward movement can provide rearward propulsion of device 1. Such capabilities could readily be automated with hard-wired control circuitry (or a microcontroller or PLC if used) by a person skilled in the art. (To illustrate this, the circuit of Figure 6 could be used if instead of a solenoid operating a brake (not shown) were to be substituted for solenoid operated valve 37. In this case, switch 78 would permit selection of forward or rear propulsion as required.)

Although device 1 has been described as being connectable to remote vacuum and fluid sources, it is of course possible to provide either or both on chassis 2.

Many other variations may be made without departing from the spirit or scope of the present invention.