AU2007100105A4 - A washing device - Google Patents

Description

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AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR AN INNOVATION PATENT

ORIGINAL

Name of Applicants: Actual Inventor: Address for Service is: University of Technology, Sydney Alexandra Gilmour SHELSTON IP Margaret Street SYDNEY NSW 2000 CCN: 3710000352 Attorney Code: SW Telephone No: Facsimile No.

(02) 9777 1111 (02) 9241 4666 Invention Title: A WASHING DEVICE Details of Associated Provisional Application No(s). 2006900653 (dated 10 Feb 2006) The following statement is a full description of this invention, including the best method of performing it known to us File: 53180AUP00 5010908321.DOC/5845 FIELD OF THE INVENTION The present invention relates to a washing device for washing articles. The invention has been developed primarily as a device for washing domestic tableware and will be described hereinafter with reference to this application. However, it will be appreciated that the invention is not limited to this particular field of use. For example, the invention is also applicable in commercial kitchens, hospitals and other environments in which washing or sterilisation of instruments or utensils is required.

BACKGROUND TO THE INVENTION The following discussion of the prior art is intended to place the invention in an appropriate technical context and allow the advantages of it to be properly understood. However, it should be appreciated that any references to the prior art in this specification should not be construed as an admission that such art is widely known or forms part of the common general knowledge in the field.

Known devices for washing tableware include automatic dishwashers, which require connection to a mains water supply and associated plumbing for proper operation. Such devices necessarily waste relatively large amounts of water, which is potentially detrimental to the environment and problematic in areas with water restrictions.

The connection to the mains water supply also typically acts as a permanent form of connection, restricting the product usage and positioning to a location in the vicinity of the mains water supply. In addition, the mains water supply must be of sufficient pressure to operate such dishwashers effectively.

Other known automatic dishwashers include smaller bench-top models which require connection to a sink faucet for water supply, with the tap left open for the total duration of the wash program. This connection requires that these models be positioned closely adjacent the sink and the associated tap ware.

Both types of dishwater draw in and drain fresh water periodically during the washing program and consequently, consume excessive quantities of clean water. On -3an average standard wash load, large capacity models use around 12L of water and smaller bench-top models use approximately 14L of water.

Energy consumption is also a concern in conventional dishwashers, as the water must be heated to provide a hygienically safe clean if the appliance is not connected to the hot water supply. Hot water connection is often not desirable as it is more expensive and does not allow for cold water usage when required.

_Conventional dishwashers also require the use of detergents for cleaning.

This results in chemical by-products being released into waterways together with the waste water and other waste materials when drained from the dishwasher, which is environmentally disadvantageous.

Sterilisation units based on steam at ambient pressure are also known.

However, such units do not provide washing functionality prior to sterilising. Another concern is the potential safety hazard, due to the risk of burn injuries resulting from contact with steam released directly into the surrounding atmosphere.

It is an object of the present invention to overcome or ameliorate one or more of the disadvantages of the prior art, or at least to provide a useful alternative.

SUMMARY OF THE INVENTION Accordingly, the invention provides a washing device including: a cabinet to contain articles to be cleaned; a reservoir to contain an initial volume of cleaning liquid; heating means to generate a cleaning vapour by heating the cleaning liquid; delivery means for selectively delivering the liquid and vapour to the cabinet to clean the articles contained therein during an initial wash program; a filtration system for filtering and purifying the cleaning liquid from the cabinet; and recirculation means for returning the filtered and purified cleaning liquid to the reservoir for reuse; whereby the initial wash program and at least one subsequent wash program can be performed using only cleaning liquid from the initial volume, with the cleaning liquid being filtered and purified for use in the subsequent wash program.

Preferably, the cleaning liquid is water and the cleaning vapour is steam. It will be appreciated, however, that additional or alternative cleaning fluids may also be used, depending upon the intended application. Preferably also, the initial volume is sufficient for the initial wash program and a plurality of subsequent wash programs, without the addition of top-up water either during or between the subsequent wash programs. Most preferably, the device is thereby adapted to operate independently of a mains water supply.

The washing device preferably includes a condenser for condensing at least a proportion of the cleaning vapour delivered to the cabinet, for recirculation to the reservoir and reuse. In one embodiment, the steam is simply condensed within the reservoir, in which case the reservoir itself also functions as the condenser.

Alternatively, however, a separate condenser unit may be provided.

The filtration system preferably includes a first stage coarse filter to filter the cleaning liquid, and a second stage ultra-fine filter disposed downstream of the coarse filter to purify the cleaning liquid to a level sufficient for reuse in the subsequent wash programs. Preferably, the ultra-fine filter is a nanofilter. The first and second stage filters may be formed within the same filter assembly, or may alternatively be formed as discrete filtration components. It is also envisaged that in some embodiments, a single component may perform both the filtration and purification functions.

In one preferred embodiment, the wash program is detergent-free and preferably includes a sterilisation cycle. The sterilisation cycle preferably uses steam generated from the initial volume of cleaning water and heated to a predetermined temperature, for a predetermined period of time, sufficient to effect sterilisation of the articles within the cabinet. In one preferred embodiment, the wash program also includes a final drying cycle.

BRIEF DESCRIPTION OF THE DRAWINGS A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a front view of a washing device according to the invention; Figure 2 is a rear view of the device of Figure 1; Figure 3 is a front view of the device in an open configuration; Figure 4 is an enlarged view of an interior of the device; Figure 5 is a schematic perspective view of a filter assembly of the device; Figure 6 is a flowchart of a steam cycle according to a first embodiment of the invention; and Figure 7 is a flowchart showing the steam cycle of a second embodiment of the device.

PREFERRED EMBODIMENT OF THE INVENTION Referring to the drawings and firstly to Figure 2, the invention provides a washing device having a water reservoir 5 which is preferably positioned on the back of the cabinet to assist with water flow in the product. The inclusion of a reservoir enables the product to have a regenerative wash program with minimal to no water loss from the system with the exception of the evaporation from steam. This component acts as a water storage area housing the initial volume of water needed for a full wash program. The reservoir in combination with a nanotechnology filter eliminates the water wastage associated with current dishwashing methods by capturing and purifying the used water for reuse.

The inclusion of a reservoir is advantageous as it provides a self-sufficient appliance without the need for plumbing installation or connection and positioning near a water supply. This enables greater flexibility of use, for example in temporary accommodation, and also helps to minimise water usage.

The water reservoir is further beneficial as it enables the product to operate at a consistent pressure making it ideal for use within country and regional areas where water supply is limited and pressure is often too low to operate a conventional automatic dishwasher. Further benefits and features are outlined below.

The reservoir holds approximately 6L of water needed for a full wash program. However, the volume is variable in relation to overall product size and wash capacity. The cabinet is preferably made of injection moulded Polycarbonate, which is relatively heat resistant and is also semi-translucent to enable users to view the water, to ensure adequate quality and maintain the correct water level needed for the product to function.

The reservoir is sealed to prevent water contamination or foreign materials from entering. To maintain water quality, the reservoir is preferably filled by pouring water through filters 10 and 11, as shown in Figure 4, within the internal cabinet to ensure an adequate supply of pure clean water.

The reservoir has been designed for removal and cleaning to prevent deposit build-ups, and also to enable the water to be readily changed. The lid is removable to allow the water to be emptied. However, the reservoir may also have a bung (small tap) which can be connected at or near the base of the reservoir to facilitate emptying the water.

Water is preferably but not necessarily released by an outlet located on the bottom of the reservoir, which acts as a one-way valve to allow the water to drain into the pump for efficient start-up. This enables the water to flow by gravity without the use of a pump, by contrast with conventional dishwashers.

The reservoir consists of two openings in which water is re-deposited during the wash program, as shown in Figure 2. The steam inlet 8 draws steam out of the cabinet during a steam cycle and into the reservoir to reduce pressure build-up and for rapid condensation. This ensures minimal water loss while also safely preventing users from coming into direct contact with steam, which conventional sterilising units do not do.

There is also a water inlet 7 where pure water has been taken from the filters and pumped back into the reservoir for reuse.

Water filtration is an important functional aspect of the product, which provides a significant advantage over conventional dishwashers. The filtration system of the present invention is preferably a two-stage system, comprising a first stage of relatively coarse filtration to capture and retain coarse particles of food or other waste products dislodged from the articles in the cabinet during the washing cycle, and a second stage of relatively fine filtration, downstream of the first, to clean and purify the water to a level at which it can be effectively reused in subsequent washing cycles or programs. The precise level of filtration at each stage may vary according to the intended application, and the number of washing cycles or programs required from the initial volume of cleaning water. However, the second stage preferably makes use of an ultra-fine filter based on micro-filtration, nano-filtration, ultra-filtration or reverseosmosis filtration. Most preferably, the ultra-fine filtration process is certified for purification of drinking water and is effective for eliminating bacteria, Giardia, cryptosporidium and potentially harmful viruses. This ultra-fine filter is preferably positioned in the sump under the first stage coarse filter so that all large scraps are initially removed from the water flow, for faster purification at the second filtration stage.

Referring to Figure 4, the washing device includes heating means in the form of a boiler 12, which is preferably ring shaped and sits on the outer side of the filter basket 11 and the ultrafiltration filter 10. This is to assist in water flow and dirt removal from the water for faster filtration. A smaller boiler is beneficial as it reduces heating time and energy consumption for the smaller volume of water needed.

Because of the high temperature of steam, the water used for washing that comes from the reservoir does not need to be heated. This minimises energy consumption and creates greater cycle efficiency in the device. Potentially there is an option of including another boiler, which heats the water before it is sprayed for cleaning. This alternative method is described in detail below with reference to Figures 6 and 7.

The top of the boiler 12 is covered with a fine mesh to prevent food particles entering the component as the water passes through to be heated. The top surface is preferably slightly convex to allow particles to wash into the removable filter basket 11 in the base of the cabinet.

The internal base and walls of the boiler are preferably formed with a nonstick surface to prevent any small particles sticking to the component when it is heated.

The outer base consists of a heating element preferably attached or plastered to its surface. This heating element heats the water to generate steam for cleaning. It is beneficial to attach the heating element to the component as it keeps the component and water warm during alternate cycles, for greater efficiency in cycle change-over and reduced energy for heating requirements. Placing the boiler on the outer area of the filters is beneficial, as it prevents food particles or scraps from rising back up and recontaminating the articles when steam is produced and rises in the cabinet.

Preferably, but not necessarily, the boiler is removable for cleaning to prevent water blockage. Preferably, small snap fasteners or clips can be used to lift the top boiler cover out of the cabinet to prevent dirt build-up and water blockages.

Various spraying methods can be used for delivering the washing water to the interior of the cabinet to clean the articles contained therein, including for example, a single rotating arm, spraying from below or two arms from above or below, or positioning of fixed nozzles within the cabinet. This is variable depending on the size of the internal cabinet, the load capacity, and the water dispersion and consumption characteristics, which the nozzles provide.

A preferable method of spraying water for the invention consists of two oscillating/rotating spray arms 13 for optimal coverage in the cabinet with minimal water consumption. The arms can be made, for example, from a tough heat-resistant plastic or a light-gauge sheet metal such as aluminium or stainless steel, stamped and welded to form the structure.

The two arms lie parallel above the sump of the internal cabinet. Each arm is embedded with four full cone spray nozzles 14 evenly spaced along the top surface.

Four nozzles are preferable. However, the number may increase or according to the size and shape of the internal cabinet, as well as the water distribution characteristics and spray angle of each nozzle. The nozzles can be made, for example, from steel, aluminium or heat resistant plastic.

Each arm preferably oscillates and/or rotates in unison at 20-45 degree angle to either side of its flat resting position. This is operated via cam and gear components located at the position where each arm connects to the piping 15, which delivers water from the pump as shown in Figures 4 and 5. This is to decrease the rotational speed for an effective clean and to reduce wear on the associated parts. Each arm is also removable for cleaning, preferably by a simple snap fit or clipping method.

Functionally, the invention is advantageous through its regenerative cycle, water purification and its use of high temperature steam as a cleaning agent. Holding the steam in the cabinet for prolonged durations during the wash program creates a sterile atmosphere and hygienically cleans items, thereby effectively eliminating the need for detergent. This in turn eliminates the chemical by-products associated with current dishwashers and hand washing methods, and results in a more cost effective and environmentally friendly washing solution.

Steam can be used in two primary methods. These are described in reference to water and steam systems in following paragraphs, with reference to flow charts in Figures 6 and 7 for the functional cycles.

Water is released from the water reservoir into delivery means which include piping leading into a top pump section 2A of a pump. An impeller (not shown) then pushes this water into the spray arms where it is released under pressure through the nozzles and into the cabinet to clean the articles contained therein.

Water released from the spray arms during the wash cycles is collected in the base of the cabinet (sump) and drained to a central point where the boiler and filters are located.

A mesh layer prevents particles falling into the boiler and the water flow effectively washes these into a filter basket in the centre of the cabinet due to the shape of the surface. Food scraps are collected and removed from the water flow. This water alongside the excess water from the boiler is drained down into the ultrafine filter.

The ultrafine filter purifies the water by means of pressure exertion removing bacteria and particles from the water. Water is then drained to the lower pump section 2B where it is pumped back into the reservoir for future washing use. The water enters the reservoir via a piping inlet located at the top, which completes the water recirculation circuit.

The water collected in the boiler is heated to generate the steam needed for the steam cycles. Water is boiled to create steam starting from 100°C and anywhere up a maximum of 200'C within the cabinet to sterilise and clean the items. The duration of the high temperature varies in the cycles according to the particular cleaning and/or sterilising needs. However, steam must be continually produced for a minimum of eight minutes during the final steam cycle for sterilisation to occur.

During a steam cycle, the steam is vented out of the cabinet through an opening, preferably located on the top back wall of the internal cabinet. This creates a partial vacuum so that the steam can be drawn out into the water reservoir and so that it cleans as it rises. Steam is vented to reduce pressure build up within the cabinet from the high temperature and for rapid condensation to minimise water loss. Venting into the reservoir is beneficial as it provides a safe method of capturing steam to prevent injury from burns, a function that is not available in current small sterilising units.

Flow chart 2 provides an alternate functional method for the invention. This involves the use of pressurized steam for cleaning in place of the ambient steam method mentioned previously. This will include a boiler with an inlet connected to the reservoir and an outlet that leads through the spray arms. This boiler will heat the water in an enclosed container. When the pressure and volume accumulated, the steam will be released under pressure out through the spray nozzles and into the cabinet for a more effective clean. The steam will be exhausted through vent and the dirt particles captured in the filters, with the water purified by the ultrafine filter 10 and pumped back into the reservoir 1 as mentioned previously.

-11 Advantageously, the system of the present invention obviates the need for dual pumps one for draining and the other for spraying water as typically required by conventional dishwashers.

An alternative arrangement of the present invention includes the use of a single pump with a split function connected to a bi-directional motor to reduce the number of moving parts and to create a more compact design. The split pump and motor system pushes water in four directions around the device according to the various cycles within the wash program. For example, when the motor spins clockwise one half (the top pump section) will draw in water from the reservoir, whilst blocking the water flow from the other half (the bottom pump section), and pass it through to the spray arms blocking off the other half of the pump. When the motor changes direction water will be taken from the ultrafine filter and pumped back into the reservoir for re-use, while blocking off water flow on the other side (the top pump section) of the pump.

Cycles have been developed for optimal cleaning in a small capacity unit.

These may vary in duration in accordance with the cabinet sizing, volume, pumping capacity and spraying method. Three preferred wash programs with optional features and variations are described below.

A full wash program consists of four alternate phases including an initial rinse, steam clean, wash and steam sterilise.

The wash program begins with a short rinse cycle to lubricate the surfaces of the articles, so as to prevent scraps from sticking. This is approximately 3-5 minutes and involves spraying of the articles with water.

The second phase is a steam cycle for approximately 5-8 minutes, which softens food particles, removes grease and oils from the surfaces and begins to kill bacteria.

On completion of the steam cycle, a longer wash cycle occurs for approximately 8-10 minutes to remove all dirt and grease from the surfaces of the articles, for a clean finish and in preparation for the sterilising cycle.

-12- The final stage is another steam cycle for approximately 8-15 minutes, which finishes the wash program with a sterilising clean. This steam is also used to dry out the cabinet, being vented as it is produced.

There is an optional drying cycle after a full wash program if the articles are required to be dry, for immediate use. This involves the use of a small extraction fan to replace the air within the cabinet.

A steam only cycle is also available to simply sterilise items in the cabinet or re-sterilise items, which have already been cleaned. This operates for around 8-12 minutes to enable sterilisation to occur.

Alternative optional wash programmes include variations of the full wash program, consisting of a two-phase cycle beginning with a longer rinse cycle and finishing with a steam sterilising cycle, again with the optional drying feature. This is preferable for half load washing.

Other feature elements of a preferred embodiment of the invention, which are variable in design, are described in the following paragraphs.

The external casing is preferably constructed of light gauge 1mm sheet aluminium to minimise the weight and cost of the product and to offer a durable surface exterior. Brushed Aluminium finish is preferred to reduce finger marks on the surface but other optional finishes could include powder-coat in numerous shades and colours or polished finish. Durable heat and chemical resistant moulded plastics are another alternative for the outer casing subject to cost and aesthetic considerations.

The external casing is designed to use minimal material and fasteners for connection. It is assembled to the internal casing with a base plate to provide a clean exterior surface clear of fasteners and offer quick access to the mechanical components in the base for ease of maintenance.

There is preferably a 25mm gap between the internal and external casing for insulation material, wiring and piping requirements. The internal cabinet is preferably made of light gauge 1.5mm sheet stainless steel. However, other thicknesses and -13-

O

0 metals are also envisaged. This can be comprised of three pieces to form a single solid structure. The top and the base are deep drawn to create the deep forms for water capturing and steam venting. The middle wall section is bent and embossed for durability and structural strength. These three pieces are preferably seam welded together to prevent heat escaping and water leakage.

This single internal cabinet structure is connected to the base structure for support. The base structure is preferably made of injection moulded polyethylene terephthalate (PET) for strength and recycling although any durable thermoplastic can be readily used. This piece supports the weight of the product and will house the mechanical components including the pump, motor, piping, electronics and wiring.

The preferred embodiment is designed with a front loading door to provide ease of access to all items. This is released by a latch and is preferably counter-weight hinged but other hinging methods are also appropriate including pulleys and springs.

The benefits of front loading include ergonomic comfort when accessing articles as this configuration enables the basket to roll out over the door frame, which reduces strain when lifting and handling articles to be washed with the device positioned at bench-top height.

The door latch is preferably mechanically locked during the wash program to prevent injury from burns that may otherwise result if the cabinet were opened with high temperature steam present. The lock is released when the cabinet is cool, steam has been vented, and the door is safe to open.

The device preferably accommodates up to four capacity settings. The size is not a limiting design feature and is subject to vary to, for example, six, eight or twelve setting capacity in accordance with the functional elements and components. The benefits of a smaller capacity device include the fact that the product can be economically used on a daily basis. Furthermore, it provides a more hygienic washing method as bacteria production is minimised through frequent washing and reduced the dwell time of dirty dishes in the sink, waiting to be washed.

The door can be made from various materials and combinations to create the desired aesthetic effect. This includes aluminium, steel and any durable -14- O thermoplastics. In reference to Figure 1, the door is constructed of four pieces consisting of a heat resistant safety glass, held in place by a sand cast aluminium frame 2, with an outer frame I made of heat resistant moulded plastic and stainless steel backing that creates the seal with the internal cabinet when closed and acts as the basket support when the door is open. This combination of materials is preferable for tt aesthetic purposes.

The basket design 9 in Figure 3 offers variations and is interchangeable with modular elements catering for individual washing requirements and the scenario of use domestic, maternity wards, commercial). The racks are allocated for optimal washing needs and prevent breakages/damage to items while being washed. The racks also separate larger items such as saucepans plates and bowls from glasses and delicates. However, items can be freely positioned. A cutlery basket is also located within the larger basket for ease of storing and unloading items of cutlery. Each basket is removable for ease of loading/unloading and storing of articles to be washed.

The filter basket is a ring shaped component that sits within the boiler to capture all the large food particles for removal from the water, which drains down into the ultrafiltration filter for purification. This can be made of a fine steel mesh or any suitable injection moulded thermoplastic. It is preferably designed to be easily removable for cleaning to prevent dirt build up and water blockage.

The present invention in its various preferred embodiments provides a safe, compact, efficient and effective washing device, suitable for a wide variety of domestic, commercial and medical applications where washing and/or sterilisation is required. The water recycling functionality ensures minimal water usage while the ability to operate without detergent reduces both running cost and environmental impact. The ability to operate independently of a mains water supply, for multiple wash programs, adds to the flexibility, portability and economy of the device. In these and other respects, the invention represents both a practical and commercially significant improvement over the prior art.

Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.

Claims (4)

1. A washing device including: a cabinet to contain articles to be cleaned; a reservoir to contain an initial volume of cleaning liquid; heating means to generate a cleaning vapour by heating the cleaning liquid; delivery means for selectively delivering the liquid and vapour to the cabinet to clean the articles contained therein during an initial wash program; a filtration system for filtering and purifying the cleaning liquid from the cabinet; and recirculation means for returning the filtered and purified cleaning liquid to the reservoir for reuse; whereby the initial wash program and at least one subsequent wash program can be performed using only cleaning liquid from the initial volume, with the cleaning liquid being filtered and purified for use in the subsequent wash program.

2. A washing device according to claim 1, wherein the cleaning liquid is water, wherein the cleaning vapour is steam and wherein the initial volume is self-sufficient for the initial wash program and a plurality of subsequent wash programs.

3. A washing device according to claim 1 or claim 2, including a condenser for condensing at least a proportion of the cleaning vapour delivered to the cabinet, for recirculation to the reservoir and reuse.

4. A washing device according to any one of the preceding claims, wherein the filtration system includes a coarse filter to filter the cleaning liquid and an ultra-fine filter disposed downstream of the coarse filter to purify the cleaning liquid to a level sufficient for reuse in the subsequent wash programs. A washing device according to any one of the preceding claims, wherein the wash program is detergent-free and includes a sterilisation cycle using steam heated to a predetermined temperature, for a predetermined period of time, sufficient to effect sterilisation of the articles within the cabinet.