High rise buildings, especially high rise glass clad office blocks, need to have the exterior cleaned.

Conventionally, the facade of such buildings in cleaned by cleaners being suspended from the roof of the building on platforms. The windows are manually cleaned and the platforms raised and lowered to make a vertical traverse of the building. A hoisting carriage ran on rails is usually designed to run on rails from the top of the building to cause the unit to traverse the building so the whole facade can be cleaned. These units are labour intensive and inherently dangerous especially in high winds.

There have been recent proposals to automate facade cleaners by incorporating cleaning nozzles, brushes and squeegees into a cleaning unit that is driven to ride up and down a facade. The units are usually suspended from the roof of a building and to overcome damage caused by swaying due to strong winds there are often tracks or mullions or guides fixed to the facade of the building on which the automated facade cleaners run. However, fixed mullions or guides are expensive and unsightly and tend to restrict one facade cleaner to one particular design of window. Thus, the units become customised and lack versatility.

It is the limitations in existing automatic facade cleaners that have brought about the present invention.

According to one aspect of the present invention

there is provided a remote controlled facade cleaner comprising a facade cleaner comprising a cleaning head supported from a displaceable carriage by a hoist to lift and lower the head, the cleaning head having brushes positioned to engage the facade ; and a cleaning fluid supply for delivery of fluid to the facade, characterised in that the cleaning head includes a plurality of spaced vacuum wheel assemblies adapted to engage the facade to hold the head against the facade as it transverses up and down the facade to clean the facade.

Preferably, the brushes are in the form of counter rotating annular brushes. The vacuum wheel assemblies may comprise a series of vacuum cups mounted on a rotating wheel whereby the vacuum cups are pressed into engagement with the exterior of the facade.

In a preferred embodiment, the cleaning head is suspended from the displaceable carriage by suspension wires that are fed from controlled drums, the feed of the wires effectively steering the movement of the head against the facade.

In a preferred embodiment, cleaning fluid and electrical power is provided to the cleaning head from the displaceable carriage.

The cleaning head in a preferred embodiment includes a squeegee assembly that trails the brushes and side seals that control escape of cleaning fluid.

In a preferred embodiment, a pressure control plate urges the cleaning head against the facade of the building.

The facade cleaner also includes a fluid filtering and re-circulation system coupled to a reservoir

fed by articulated scoops positioned beneath the cleaning head to collect excess cleaning fluid.

Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a side elevational view of a cleaning head that forms part of the facade cleaner, Figure 2 is a front view of the cleaning head, Figure 3 is a rear view of the cleaning head, Figure 4 is a rear view of a hoisting engine that forms part of the facade cleaner, Figure 5 is a side view of the hoisting engine, Figure 6a is a side view of a brush that forms part of the cleaning head, Figure 6b is an enlargement within the circle B of Figure 6a, Figure 7a is a front view of the brush, Figure 7b is an enlargement within the circle B of Figure 7a, Figure 8 is a side elevational view of a vacuum wheel that forms part of the cleaning head, Figure 9 is a front on view of the vacuum wheel, Figure 10 is a side view of a water recycling scoop that forms part of the cleaning head, Figure 11 is a rear view of the scoop, Figure 12 is a front view of the scoop, Figure 13 is a schematic illustration of the fluid control system for the facade cleaner, Figure 14 is a side elevational view of a facade cleaner in panel format forming a second embodiment of the invention, Figure 15 is rear view of the panel format.

The robotic facade cleaner 10 illustrated in the accompanying drawings essentially comprises a hoisting carriage 20 that drives a hoist 40 that in turn causes a cleaning head 50 to complete vertical passes up and down

the facade of a building. The hoisting carriage can be moved transversely to ensure that the whole facade of the building is covered by a plurality of parallel vertical passes of the cleaning head. The hoisting carriage 20 incorporates an engine and drive mechanism for the hoist 40 and carries the control panel and other equipment that are controlled by a single operator.

As shown in Figures 4 and 5, the hoisting carriage 20 comprises a rectangular frame 21 that is arranged to run on wheels 22 that can be free wheeling or driven and/or steered. The frame 21 supports an electric drive motor 23, drives three co-axial drums 24,25, 26 through belt or chain drives, the drums are mounted to spin on slip rings. The forward edge of the rectangular frame 21 carries three equally spaced laterally extending jib arms 27,28, 29, two 27,29 of which supports an adjustable jib that carries a hoisting wire 30. As shown in Figure 5 each hoisting wire 30 is thread through a series of pulley wheels to be wound onto the respective drums 24 & 26. Each jib comprises a hollow arm 31 member connected at an elbow joint 52 and terminating in an end joint 33. The end joint 33 is mounted on a slider 34 that can slide horizontally along the jib arm from an extended position shown in Figure 5 to a retracted position also shown in the same Figure. A suitable electric motor provides a linear drive that causes the jib to assume the two positions shown in Figure 5.

The electric motor 23 is coupled to a gearbox which is coupled to a main drive shaft. The main drive shaft is itself coupled by roller chains to the three drums 24,25, 26 two of which each hold a quarter inch diameter galvanised wire rope with two electrical connector cords each and the other holds a 6mm diameter nylon tube 39. The drums are multi-layered and are fixed to the base by a drum frame. The drums 24,25, 26 may be

removed from the frame 21 by removing the associated roller chains, removing the retaining butterfly bolts and sliding the drum's axial supports out of their location.

As shown in Figure 5, the drum frame rests on a chassis which is attached to the base by two linear guides 36. A cam track 37 driven by a worm gear attached to the drive shaft is engaged with a cam follower mounted on the base. The rotation of the drive shaft causes the cam track to rotate. The reaction of the cam track against the cam follower causes the chassis to reciprocate relative to the base and a first set of pulleys. This rotation is cyclical and is related to the rotation of the drums. The reciprocation along the axis of the drum allows the wire ropes to wind on and off in an even manner, the movement of the drums relative to pulleys fixed to the support structure being just sufficient to provide winding space for the ropes directly beneath the pulleys at all times thus providing maximum rope capacity on the drums.

The cleaning head 50 is effectively supported by the two outer wire ropes 30 with water being transmitted to the cleaning head via the nylon tube 39. The cleaning head, which is described later, can be steered by the reciprocating hoist.

The wire ropes 30 and nylon tube 39 extend from the drums upwards to the first set of separate pulleys 41 on the aluminium frame where the ropes are directed in opposite horizontal directions whilst the tube is directed to the centre of the frame. The wire ropes wind around a second set of pulleys 42 which are mounted on a slide 43 held in a track 44. The ropes then wind around a third set of pulleys 45 which are fixed to the support structure.

The slide is attached to two electrical linear drives 46 which may cause it to move to the left or to the right.

This movement will increase or decrease the path length of

the two ropes 30 which causes the ropes to apparently shorten or lengthen with respect to each other. The result of this differential change in apparent rope length is the tilting of the cleaning head to the left or to the right.

As described below, the cleaning head grips the building facade with suction wheels mounted on axles and as it is tilted the axles will also tilt and create a tendency for the cleaning head to be steered left or right as it moves up and down the building. This enables the cleaning head 50 to be brought back into position directly beneath its support points should it have moved from here due to a prevailing wind.

The cleaning head 50 is also designed to be able to luff or be displaced to and from the buildings facade.

In the case of the roof mounted unit the ropes and tube are guided along and around the frame to sets of rollers mounted on axles at the articulation of the rollers'support arms. The rollers'support arms are pin- jointed at their innermost ends to the jib arms 37 whilst their forward ends 33 rest on a beam mounted on sliders 34 which is able to slide back and forth on the top surfaces of the jib arms. The support may be extended or retracted by a linear drive fixed on both sides of the articulation.

The ropes and tube are led to rollers at the forward ends of the arms. The ropes and tube are then directed downwardly adjacent to the facade. The operation of the linear drive brings the rollers supporting the ropes towards or away from the hoisting engine and in this way the cleaning head is brought towards or away from the building's facade.

The water and electrical power is provided to the cleaning head from the central drum 25.

The hoist ends of the ropes 30 are located at the

drums at their central axes. A swivel coupling connects the water supply to the nylon tube and two electric slip rings and brushes connect the electrical supply and the control signals to the conductor cores of the two wire ropes. As shown in Figure 13, a first hose 11 delivers mains water to a strainer 12 mounted on the base of the support structure. A second hose 13 takes the water via an electrically operated valve 14 to a first pump 15 which pumps water through a third hose 16 to the swivel coupling and into the bore at the hoist end of the nylon tube. The water flows through the nylon tube down to the cleaning unit where it is collected in a reservoir 17. A level sensor 18 in the reservoir 17 detects when the level of the fluid falls below a predetermined level at which point a signal is sent through the electrical signal rope to the support structure to initiate operation of the first water pump 15 and to open the electric valve 14. Electricity is supplied to the cleaning unit through the slip ring assembly and the electrical conductors in the electrical supply wire rope.

As shown in Figures 1 to 3, the cleaning head 50 consists of a central chassis 51 made out of an aluminium cylinder closed at both ends 52,53 from which radiate twelve curved aluminium tubes 54. The chassis 51 supports the motor and gearbox to drive two counter rotating brushes 60,61, a second pump to suck the fluid out of the reservoir 17 and pump it through nozzles 70 at the brushes 60,61, the radio control receiver and the electrical control box. Two stainless steel arms 55,56 are attached by'u'bolts to the rear of the chassis. The two suspension wire ropes 30 are attached to the ends of these arms 55,56. The curved aluminium tubes 54 carry a brush support 63. Three lower aluminium tubes are connected to and support the lower assembly. The two steel arms carry an aluminium angle bar 59 which supports a squeegee assembly 80.

The brush support 63 is attached with flanges to the ends of the curved aluminium tubes 54. The support 63 is made out of a ring of thick polycarbonate. It carries eight idler roller assemblies 64 and two drive wheel assemblies 65, 66. The idler wheel assemblies 64 consist of two polycarbonate pulleys. The drive wheel assemblies consist of aluminium timing belt drive rollers fitted with gears and driven by flexible drives coming from the circular body.

As shown in Figures 6 and 7, the two brushes 60, 61 are made out of thick concentric polycarbonate rings which are drilled at regular intervals for the insertion of black nylon bristles 69, arranged in bunches. The inner brush 61 has a timing belt 67 attached to the entire circumference of its inner face whilst the outer brush 60 has a timing belt 68 attached to the entire circumference of its outer face. This belting is made of rubber and engages with the aluminium drive rollers. The idler rollers 64 act as guides and restraints for the circular brushes 60, 61 whilst the drive roller assemblies spin the brushes. The brushes each have a wide, continuous strip 85 of thin neoprene rubber attached to and threaded in a serpentine fashion in and out of the bunches of bristle 69 all the way round the polycarbonate rings. These strips of neoprene act as barriers to the cleaning or rinsing fluid spray which originates from sideways-firing nozzles mounted between the two brushes so the spray is confined to the space between the brushes.

As shown in Figures 1 to 3, the cleaning head 50 is fitted with a brush pressure control plate 100. This is a flat circular vertical aluminium plate with an opening 101 in it slightly larger than the chassis 51 so that it can pass over the chassis. It is attached to a miniature horizontally operating electrical scissor jack 105 fitted

to the end of the central chassis facing the building.

Horizontal guides fitted with rollers are attached to the pressure control plate 100 at regular intervals and these bear on the outer surface of the central chassis 51, constraining the pressure control plate to maintain its verticality irrespective of its position relative to the central chassis. In use the scissor jack 105 is operated in conjunction with vacuum devices, described later, to bring the cleaning head 50 and hence the cleaning brushes 60,61 closer to and farther from the facade, thereby enabling the operator to initially establish contact with the facade and then in conjunction with the grip provided by the vacuum devices to apply a controlled amount of pressure on the facade with the brushes to enable positive cleaning to take place.

As shown in Figure 2, the pressure control plate 100 is fitted with a number of wheel-type vacuum devices 120. They are used to hold the cleaning head 50 against the side of the building whilst pressure is being exerted on the facade by the cleaning brushes 60,61. They enable the cleaning head 50 to grip the building whilst moving up and down and help the cleaning head to maintain contact with the building in windy conditions and avoid dangerous swaying. The devices 120 are arranged around the rim of the suction plate. As shown in Figure 2, they are arranged asymmetrically so that the vacuum cups release their vacuum at different times when horizontal or vertical glazing bars are encountered. This reduces the coherence of reaction forces and as a consequence the cleaning head moves more smoothly.

As shown in Figures 8 and 9, each vacuum wheel 120 consist of vacuum cups 121 made of a resilient material attached to short tubes 122 which are a sliding fit in holes 123 bored in a circular hub 124 perpendicular to its axis. The hub 124 is supported on an axle 125 held

in a zU'shaped chassis 126. The tubes carry springs 127 which react against the vacuum cups 121 and the hub. This gives the vacuum cups 121 the ability to move towards the hub against spring pressure and to return to their original position. This freedom of movement perpendicular to the axis of the hub enables a first vacuum cup to keep its grip on a smooth surface and allow a second following cup on the same hub to establish its grip on the same surface before the first vacuum cup releases its grip.

This is a continuous process and enables the suction wheel to negotiate small obstructions without loosing its grip on the surface.

As shown in Figure 2, the squeegee assembly 80 is made of three rubber squeegee strips 81,82, 83 held in spring loaded parallelograms which maintain the squeegees in contact with and at ninety degrees to the facade and sweep the facade dry. When the squeegees encounter an obstruction, for instance a horizontal glazing bar, the squeegees are able to move up or down and away from the facade against the spring tension and avoid being damaged.

The central squeegee rubber 83 is a single continuous strip. The two outer squeegees 81,82 are made of two 50mm wide rubber squeegee strips each, the strips being cut through their thickness at right angles to their long axis at intervals of 20mm to a depth of 40mm. The squeegee strips are arranged one on top of the other 20mm apart laterally offset by 10mm relative to the cuts. This arrangement enables the squeegee strips to squeegee a surface next to a vertical glazing bar without missing much of the surface. The cuts allow the squeegee strips to conform more closely to the profile of the surface than a continuous squeegee would permit. The 10mm offset helps the following squeegee strip to cover those parts of the facade missed due to the cuts in the leading squeegee strip.

The nylon tube 39 suspended from the hoisting

engine delivers water into the reservoir 17. The water passes through a pipe connected to the bottom of the reservoir, through a strainer 12 and then to a'T' junction. Both arms of this junction are connected to remotely controlled electric valves 14,14A. One valve 14A feeds the water into a filter 19. The other valve 14 feeds the water to a second'T'junction. One arm of this junction is connected to a manually operated valve which is connected to a soap dispenser 9. The other arm is connected to a tube which is connected to a third'T' junction. One arm of this junction is connected to the outlet from the soap reservoir and the other arm is connected to a fourth'T'junction. One arm of this junction is connected to the filter 19 and the other arm is connected to an electric pump 15 within the main chassis. The output from the pump is fed to both ends of a tube which is attached to the brush support. This tube is fitted with sideways spraying water nozzles at regular intervals along its length. The fluid is sprayed sideways onto the two circular brushes 60,61 which will clean the facade. The used fluid flows down the facade into the reservoir 17. The electric valves provide either a soap and water mixture for washing or filtered water for rinsing to be sprayed onto the brushes. The manually operated valve adjusts the proportion of soap that is mixed with water to make the washing fluid.

The cleaning head 50, as shown in Figures 1 to 3, has a lower assembly 150 constructed of aluminium. The assembly 150 carries the reservoir 17, filter 19, soap dispenser 9, valves and an obstruction detector 155 installed underneath to stop the hoisting motor if the cleaning head touches something on its descent. The reservoir 17 consists of an arc-shaped box 151 open at the top made out of polycarbonate. Rubber-tipped plastic scoops 156 shown in Figures 10 to 12 are mounted on the inside face of the reservoir 17 and extend past the outer

wall of the reservoir towards the building facade. When the brushes 60,61 are in contact with the facade of the building these scoops 156 are biased against the facade by springs 157. The scoops 156 collect the used fluid as it flows down the facade and return it to the reservoir 17.

The scoops are articulated across their width and are spring-loaded. When ascending and on meeting an obstacle, for example, a glazing bar, the scoops bend at their articulation and avoid being damaged and spring back when the obstacle has been passed. Each scoop moves independently of the others so if a protrusion is encountered it will affect only one scoop.

As shown in Figures 1 and 2, an aluminium section 170 is fitted between the brush support and the reservoir on both sides of the cleaning head. A neoprene strip 171 is attached to the edge of this section facing the facade of the building. Nylon bristles are attached to the whole length of the neoprene strip. This structure touches the facade of the building and forms a sliding seal with the facade. It stops fluid flung off the brushes by centrifugal force from landing on adjacent surfaces and guides the fluid into the reservoir 17.

In cases where a facade consists of wide flat surfaces it is advantageous to use a facade cleaner in panel format that is illustrated in the second embodiment in Figures 14 and 15. The facade cleaner 200 is in the form of a rectangular panel and incorporates a set of linear orbital brushes 201 that are used with other components of the facade cleaner described in the first embodiment such as vacuum wheels, water scoops, sprays, squeegees, and other componentry. However, as shown with reference to Figures 14 to 15, linear brushes are used instead of the counter rotating brushes and the assembly has a flat rectangular profile as shown in Figure 14.

The two embodiments of facade cleaner as

described above have many advantages, a few of which are listed hereunder: No one is required to work at height outside a building. Only one person is required to operate the equipment and he stays on the ground except when moving the roof car. The roof car may be fitted with driven wheels and a guide track in which case the operator may always stay at ground level except for set-up and storage of the equipment. The equipment works at a constant speed and will give consistent results. By not having operators outside windows the privacy of the building's occupants is maintained. The cleaning head weighs less than 75kgs and in Singapore at least it falls below the weight above which equipment must be load tested (120kgs) so it may be deployed and transferred without a site test, but it will of course, be tested before it leaves the factory. The cleaning head's light weight allows its use on sloping and curved glass structures. The equipment has a large factor of safety due to the use of two 1/4"diameter steel wire ropes. The hoisting engine is relatively light at 200kgs and can be dismantled for ease of moving and storage.

The light weight of the equipment means that it can be installed on most buildings without any additional reinforcement to the roof slab or parapet. Aluminium, stainless steel and plastics are used extensively in the equipment. This reduces rusting so maintenance costs will be low. The cleaning head may be deployed at the roof so a facade which cannot be accessed from its base because of, for example, a glass canopy, can be cleaned. The cleaner's small size and light weight enable it to be easily retrofitted to existing buildings. The cleaning fluid is recycled so usage and spillage of water is minimised. The location of the power supply and control wires within the wire ropes provides armoured protection to the electrical supply and the supply of water down the nylon tube makes

it unnecessary to have a heavy reservoir to hold the cleaning fluid.

The design uses passive vacuum devices so that in the event of a power failure the machine will continue to grip the building for some time and any lifting or lowering of the machine will automatically restore the grip. By using contra-rotating brushes no torque is imposed on the cleaning head and the bristles can get into every crevice in the facade. In the event of a supply failure the cleaning head will eventually lose suction and so may be blown in the wind and could damage the building.

To cope with this eventuality the cleaning head is surrounded by soft rubber buffers and a manual release is incorporated in the hoisting motor so that the equipment may be brought down without power. The cleaning head is connected to an independent safety line by a fall arrestor. The safety line is tensioned at the base of the building and this prevents the machine from swaying away from the building and causing damage to the facade on its return swing. An inverter with a storage battery to provide an uninterruptible power supply may be installed in the hoisting engine so that the equipment may always be powered and landed at the roof top.

It is envisaged that many other features and improvements can be incorporated within the facade cleaner whilst falling within the scope of this invention.