DESCRIPTION OF THE PRIOR ART Driveways and pathways, and other hard-surface areas are prone to become dirty and discoloured for a variety of reasons, for example, due to spills or oil and other chemicals, due to the growth of moss and mould, and due to general usage and environmental dirt and dust, etc.

Presently, there are two common methods by which such surfaces are cleaned.

The first is by applying a cleaning agent, such as an abrasive chemical or acid, and scrubbing the surface with the aid of a brush or like implement. As will be appreciated, this is a laborious, time-consuming and somewhat expensive task.

The other known, and more recently developed method, is the use of a high pressure spraying device, which provides a narrow stream of high pressure water from a wand-like tool. The tool is moved from side to side such that the high pressure stream is transversed over the entire surface in a systematic manner. Whilst it is appreciated that this method is different to the aforementioned method and is perhaps less physically exerting for the person operating the device, it is still somewhat time-consuming and expensive to operate.

Therefore, a need is identified for providing a device and method for cleaning driveways, paths, patio areas and like hard surfaces which ameliorates at least some of the disadvantages of these prior art devices and methods.

SUMMARY OF THE INVENTION The present invention seeks to provide a device and method for cleaning hard surfaces such as concrete and tiled surfaces, driveways and the like.

In one broad form, the present invention provides a cleaning apparatus, including : a substantially enclosed, such as concavely shaped head ; an inlet hose connected to said head to supply a high pressure liquid jet to said head.

Preferably, said inlet hose is connected to said head by a universal joint enabling three dimensional movement of said inlet hose relative thereto.

Also preferably, a controlled stream of liquid is supplied towards a substrate surface from said inlet hose.

In a preferred form, the liquid is heated.

In a preferred form, said liquid is water and optionally includes a cleaning agent.

Preferably, said high pressure liquid is supplied to said inlet hose from a hydraulic control system.

In a preferred embodiment, said hydraulic control system is powered by an automobile engine.

Also preferably, the hydraulic control system is operated by said automobile engine when an electromagnetic clutch is engaged.

Preferably, said hydraulic supply includes means for self regulating the pressure of said high pressure liquid supplied to said inlet hose.

In a preferred form, said hydraulic circuit includes a throttle adjuster, to sense

hydraulic system pressure and thereby control engine speed, an inverter, etc..

Also preferably, said hydraulic circuit further includes a heater to heat said cleaning liquid.

Preferably, said heater is powered by said automobile engine via an inverter (DC to AC).

Also preferably, a pressure switch is used to sense when a high pressure jetstream is required to then operate said heater.

Also preferably, said hydraulic system further includes a header tank.

Preferably, said header tank is connected to a mains supply, the water passing through a heat exchange.

In its most preferred form, said apparatus is used to clean concrete, tiled, paved or other hard substrate surfaces, typically used on driveways, paths and patio areas, for removal of dirt, oil and chemical spills, moss and mould, etc.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will become more fully understood from the following detailed description of a preferred but non-limiting embodiment thereof, described in connection with the accompanying drawings, wherein : Fig. 1 illustrates a preferred embodiment of the apparatus, showing the head and fluid inlet hose ; and, Fig. 2 shows a schematic representation of the hydraulic control system of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT (S) The apparatus 1 depicted in Figs. 1 and 2 shows the cleaning head 2, and the hydraulic control system (Fig. 2,) respectively, forming the device and method for cleaning, in accordance with the present invention.

The cleaning head 2, as illustrated in Fig. 1, is typically a housing of substantially concave shape as shown, having an inlet hose 3 connected thereto, preferably centrally, to supply a high pressure liquid jet to said head. Any other substantially enclosed shaped housing may alternatively be used.

The inlet hose 3 is preferably connected by means of a universal joint connection 4, allowing maximum three-dimensional movement of the inlet hose 3 relative to the head 2.

This enables the head to be provided underneath low-lying objects, etc., ensuring maximum manoeuvrability of the head to reach relatively inaccessible locations for performing cleaning operations.

The liquid jet supplied to the head may be directed in a variety of manners, depending upon the particular type of surface to be cleaned and upon the material to be cleaned therefrom. For example, a single centrally provided jet stream may be directed towards the substrate surface, or, a plurality of finer jets may be dispensed at any desired angle, etc.

Additional mechanical devices, which rotate or otherwise operate may be provided under the head for additional cleaning function, if desired. Furthermore, the liquid jet may be water, and/or may include chemical additives such as cleaning agents, and/or may be heated.

It will be appreciated that the ability to effectively clean using the head as shown in Fig. 1 is achieved by the associated use of an appropriate hydraulic circuit to supply the liquid at the desired pressure, etc. An appropriate hydraulic circuit to achieve this purpose is illustrated in Fig. 2. Whilst it will be appreciated that a variety of alterations and modifications may be enacted to such a circuit, whilst still achieving the functional requirements for effective cleaning to be achieved by the cleaning head of the apparatus, the Applicant has designed a device which is uniquely powered by an automobile engine and

which is self regulating, providing a consistent high pressure jet stream to perform the required cleaning function, a low pressure wash down stage, and, an idle stage whereby the motor speed is reduced to minimise noise, fuel consumption and increase operating life. The equipment is preferably installed on the back of a utility or like vehicle, in a manner which it is able to be easily set up for use and then packed up when finished. A multiple rib drive belt system with an electromagnetic clutch to disconnect the hydraulic pump drive from the vehicles engine is used to remove the need for an auxiliary engine to drive the high pressure wash pump. This reduces the maximum engine noise to that the vehicles engine, and also reduce the weight and increased space at the rear of the vehicle.

A heating unit, to heat the water, is installed in the vehicle. For washing, the water is heated to over 802C. A sine-wave power inverter is used to convert the vehicles DC power to AC, which power the heating units fan and electrics. By using an inverter, the need for an auxiliary generator is eliminated, which reduces weight and space requirements. A unique feature of the heating system is that a pressure switch is used to switch the heater on and off.

This pressure switch is set so it is above the wash down pressure and high pressure cleaning pressure. Therefore, the heater only works when high pressure cleaning and not when low pressure washing down. The larger jet in the wash down nozzle changes the pressure so the operator does not need to go back to the vehicle and turn the heater on and off between high pressure cleaning and low pressure wash down.

A hydraulic throttle valve is fitted to the engine which senses the hydraulic system pressure to control the engine speed. This gives the system some unique characteristics.

Firstly, when the high pressure water is shut off via a gun or ball valve, an unloading valve unloads the high pressure water system, reducing the pressure in both water and hydraulics.

This is a standard high pressure water system. This reduction in the pressure of our hydraulic system is detected at the pressure sensing throttle we have fitted and reduces the engine speed to idle when the outlet water is shut off. This reduces noise, reduces fuel consumption and increases the operating life of the hydraulic system. Secondly, the throttle valve has the advantage that it governs the system and adds a safety feature, in that if a high pressure hose should burst, the truck immediately goes to idle reducing excess hot or cold

water being blown around out of control. The hydraulic engine throttle therefore allows our trucks engine speed to be precisely tuned and maintained when the system is running.

A header tank of water to supply the high pressure water tank is also provided. When the supply hose is connected to an external water supply, the water passes through a heat exchanger with the hydraulic system oil flowing through it. By using tap water to cool the hydraulic system the size of the systems hydraulic tank is able to be reduced, consequently reducing vehicle weight and saving space.

The hydraulic control valve is built with a unique configuration to simplify the vehicles operation and reduce weight. The basic operation of the valve, in activating the operating lever into position achieving the following automatically. Firstly, an electric switch on the valve engages the electromagnetic clutch. At the same time, the oil flow to the hydraulic motor sends a signal to the engine throttle which automatically sets the engine to the correct RPM, such that the pressure switch then operates the burner. The hydraulic valve has a safety overflow valve built into the inlet to protect the water pump and port reliefs to control the retraction speed of the reels.

The hose reels for the cleaning device may be fitted with hydraulic motors to systematically reduce the effort and time of packing up the systems.

Therefore, by combining the hydraulic, electric and water systems in this configuration and using the vehicles original engine to power the system, a system with substantial reduction in noise, size, weight and running costs has been achieved. The interconnecting of the system has simplified the set up and pack up times and the operation of the system.

The hydraulic circuit shown in Fig. 2 is a unique self-regulating circuit incorporating a pressure sensor, throttle adjuster and inverter to achieve this effect and provide a high pressure liquid jet.

For normal cleaning operations, the cleaning fluid is typically supplied at between 12, 410 kPA to 27, 258 kPA at a rate of greater than 18 litres per minute and at a temperature of greater than 80°C. For wash down, the pressure is typically less than 6 kPA.

The present invention therefore provides a cleaning apparatus which has a unique cleaning head in addition to a unique hydraulic circuit to supply a regulated high pressure fluid steam to perform the desired cleaning operation.

The hydraulic flow can be reduced via the control valve, which enables the water flow and pressures to be reduced, easily and accurately to clean delicate surfaces.

Whilst a particular embodiment has been herein described, it will be appreciated that numerous variations and modifications may be made to still achieve the functional objectives of providing a compact, lightweight, transportable apparatus which is quickly and easily operated to clean a variety of hard substrate surfaces, including relatively difficult and inaccessible surfaces in an effective manner.

The device of the present invention therefor may be used to remove oil, grease, moss, chewing gum and other grime from the pavement and similar surfaces. This avoids the need to use harmful caustic chemicals.

The problem with many prior high pressure systems is that they damage aged concrete and tear up the grouting between your pavers and tiles. The system of the prior invention accurately controls pressures and will not cause any such damage.

The device of the present invention is also considerably less noisy than prior art systems. The circuit of the present invention can be operated at below 80 decibels, enabling work to be conducted 24 hours a day, if required.

The device of the present invention has many applications, including, but not limited to :- Footpaths * Concrete Driveways Pebblecrete * Pavers Sandstone # Stencilcrete # Workshop Floors # Car Parks # Decorative Flooring # Pool Surrounds # Tennis Courts # Preparation of floor surfaces for sealers to be applied # Airport Hangars and Runways # Food Processing Plants # Fruit Juice and Drink Factories # Breweries Flour Mills All such variations and modifications should be considered to fall within the spirit and scope of the invention as broadly hereinbefore described.