Background To The Invention Over a period of time supermarket trolleys become unhygienically grubby and are sent periodically in batches for cleaning. The trolleys which are out of the store for cleaning inconvenience, because of the decreased number of remaining trolleys, shoppers and to store managers with this generally resulting in the store having to purchase and keep on hand a greater number of trolleys than are generally required for normal business.

Object Of The Invention It is an object of this invention to provide a self contained spray booth for spray cleaning objects such as supermarket trolleys.

Summary Of The Invention In this specification the meaning of the term"liquid"is to be taken to include steam.

A mobile spray booth according to the invention includes a wheeled motor vehicle trailer frame, a housing on and over the frame, openings into and out of opposite sides of the housing, a floor in the housing between the two openings on which objects to be cleaned are moved, in use, between the openings, liquid spray nozzles, which are directed into the space over the floor, on at least opposite sides of the floor, and means for feeding liquid under pressure to and from the nozzles.

The housing floor between the openings may be in the form of an endless conveyor for transporting the objects through the housing between the openings.

Conveniently the booth includes a sump beneath the housing floor between the openings for collecting sprayed liquid.

In one form of the invention the liquid feed means includes a pump for pumping liquid through suitable conduits to the spray nozzles. The pump inlet may be connected to pump liquid from the sump to the nozzles.

The feed means may additionally include a suitable heat exchanger between the pump and spray nozzles for heating the liquid. Preferably the liquid is heated by the heat exchanger to high pressure steam which is fed to the nozzles.

The booth may additionally include a fuel operated electrical generator for operating the conveyor floor, the pump, the heat exchanger and perhaps other electrically driven equipment in the housing.

To facilitate feed of the objects to and from the housing opening the booth may include suitable stowable ramps to and from the booth housing.

The mobile spray booth may be configured for transport to a shopping mall for the cleaning of shopping trolleys or shopping carts at the shopping mall.

In another embodiment, the mobile spray booth is configured for transport to a storage depot for the cleaning of crates at the depot.

The invention extends to a method of cleaning objects in situ at the premises at which the objects are normally located, the method including the steps of: -transporting the booth as described above to a first premises where objects to be cleaned are located; -cleaning the objects by passing them through the booth; and -transporting the booth to a further premises where other objects to be cleaned are located.

The objects may be shopping carts or trolleys in which case the premises are the parking lot of a shopping mall where the shopping carts are located.

Likewise, the objects may be crates, in which case the premises are a storage and/or packaging depot where crates are returned to by the public and must be cleaned for reused.

Brief Description Of The Drawings An embodiment of the invention is now described by way of example only with reference to the drawing in which: Figure 1 is a diagrammatic sectioned side elevation of the spray booth of the invention, and Figure 2 is a plan view of the booth of Figure 1 shown sectioned on the line 2-2 in Figure 1.

The spray booth 10 of the invention is shown in the drawings to include a wheeled towable trailer frame 12, a housing 14 which is located on and over the frame 12 and includes inlet and outlet openings 18 and 18 respectively, and trolley ramps 20 over which supermarket trolleys may be run into and out of the housing 14.

The housing 14 includes a floor with a portion of the floor over the length of the housing being defined by an endless conveyor 22 with the conveyor belt conveniently being made from a water pervious material. A large capacity water sump 24, shown in Figure 1 only, is located beneath the central portion of the conveyor as shown in the drawing. The upper surface of the sump is dished towards an inlet to enable water on the upper surface of the sump to be gravity fed into the sump tank.

The housing additionally includes a series of steam spray nozzles 26 which extend over the side walls and roof of the conveyor compartment of the housing with the nozzles being connected to suitable steam conduits from a steam generating heat exchanger 28.

The heat exchanger 28 is fed with water from the tank 24 by a pump 30 and the housing additionally carries a fuel driven electrical generator 32 for providing electrical power to the heat exchanger 28, the pump 30 and a drive motor 34 for the conveyor 22.

The housing openings 16 and 18 are closed by doors which are not shown in the drawing and additionally may include strip curtains for trapping vapour in the housing and through which the trolleys may simply be moved through the openings 16 and 18.

The ramps 20 are articulated and easily removable from the housing brackets to which they are attached for stowage in a housing compartment 36. Alternatively, to avoid the mounting and demounting of the ramps 20 the ramps could be further articulated so that they could be folded into the housing to lie on the conveyor 22 while the spray booth is not in use. The running surfaces of the ramps could be made from lightweight expanded metal or the like.

In an alternative embodiment, not shown, the ramps 20 could be fed by a conveyor system.

In use and with the sump tank 24 filled with water and perhaps a suitable degreasing agent in bactericide the spray booth is towed to a site of use such as a convenient spot in a supermarket car park. The ramps 20 are then folded out of the housing or removed from the housing storage compartment and erected as shown in the drawings. Dirty and grubby supermarket trolleys are then run up the left hand ramp in the drawings and into the housing 14 through the inlet 16. The electrical generator 32 is started to supply electrical power to the housing components 28,30 and 34. The motor 34 drives the conveyor through a suitable step-down gearbox to move the conveyor to transport a trolley which has run onto the conveyor at the inlet 16 at a desired speed through the housing. The pump 30 in the meantime pumps liquid from the sump tank 24 to the heat exchanger which converts the liquid into high pressure steam which is then fed to the spray nozzles 26. As the trolley passes through the central nozzle zone of the conveyor chamber of the housing it is steam cleaned by the high pressure steam and whatever chemicals the water may be dosed with.

Additionally, the heat of the steam serves further to sanitise the trolleys. A series of

trolleys is fed in a continuous steam through the housing inlet 16 onto the conveyor and the clean trolleys are intercepted at the outlet 18 of the housing and fed down the right hand ramp 20 in the drawings.

The steam condensate in the housing is gravity-fed to the inlet to the tank 24 for recirculation.

By use of the spray booth of the invention the inconvenience to store managers, as mentioned in the preamble to the specification, is almost entirely eliminated as the trolleys are rapidly cleaned on site without water sillage and waste and returned to service.

The invention is not limited to the precise details as herein described. For example, although it is preferable that the spray booth carries its own self contained electrical power source this could be eliminated from the booth which could be electrified by a suitable extension cable from a fixed external power source. Additionally, the spray booth could include, in place of the single sump tank 24 two tanks with the additional tank being a clean water inlet tank to the mobile spray cleaning booth and the tank 24 a collection tank for dirtied water which is passed to the heat exchanger after being filtered. In yet a further variation, the conveyor chamber of the housing could include, on the downstream side of the spray zone in the chamber, compressor driven air nozzles for at least partially blow drying the trolleys as they leave the housing outlet 18.