FABRIC CLEANING APPARATUS

DESCRIPTION

The present invention refers to a fabric cleaning apparatus.

The use of plasma to remove stains of organic substances from fabrics is known from the disclosures in JP2005087540, JP2005087541 and JP2005224757.

In particular, JP2005224757 discloses a plasma cleaning device intended for application to a hand iron. The plasma cleaning device is provided with an inlet to take in steam jetting out from the bottom surface of the hot plate, i.e. the flat base of the smoothing iron, a pair of metal electrodes producing plasma at atmospheric pressure, and an outlet discharging chemically very reactive molecules and atoms that are generated in the plasma.

The steam taken in through the inlet is introduced across the pair of metal electrodes of the parallel-plate type forming a dielectric-barrier discharge assembly, which are connected to a high-voltage AC generator for a discharge current to be produced across the pair of metal electrodes by having a predetermined electric field impressed, i.e. applied thereupon.

Dielectric-barrier discharge assemblies are characterized by the presence of one or more dielectric layers in the current path between a pair of metal electrodes provided in a mutually facing arrangement so to form a gap therebetween, in which an aeriform or gaseous medium, such as for instance air and/or steam, is present as it flows therethrough.

When an AC voltage is applied to such electrode arrangement with one or both electrodes covered by a dielectric layer, a dielectric barrier discharge (DBD) appears in the gas gap between the two electrodes.

A DBD consists of a number of self pulsing micro-discharges in the gas gap (or discharge gap), with corresponding surface discharges on the dielectric. The time

constant of these processes lies in the nanosecond region. The electric energy coupled into the gas is mainly used to produce energetic electrons, while the gas remains at nearly ambient temperature.

Due to them colliding with the energetic electrons, the molecules in the steam that flow between the parallel-plate type electrodes are ionized, dissociated and excited, thereby generating active species, i.e. extremely reactive particles chemically, e.g. OH ^" , H ⁺ , O atomic, O ₃ , N atomic. The thus generated active species are discharged from the outlet onto the stained fabrics to be cleaned.

These active species either react with the organic substances of the stain chemically, thereby forming volatile compounds that are released from and leave the fabric, or act by oxidizing the organic substances of the stain so that they can then be simply brushed off. In practice, these active species attack the organic material of the stain chemically, so that the latter is disgregated and removed without any assisting liquid solvent being required in the process.

The plasma cleaning device disclosed in JP2005224757 has a number of drawbacks. In the first place, the device is scarcely convenient in use, since - to have it operating - it is necessary for the flat iron base to be applied onto an upper portion of the device, where the inlet to the discharge gap is provided, so as to supply the latter with the steam produced by the hand iron.

Another drawback arises from the fact that it practically proves quite awkward for the outlet from the discharge gap to be appropriately positioned in proximity of the organic substances forming the spot staining the fabric to be cleaned. It can be most readily appreciated that the closest the outlet from the discharge gap is positioned to the stain to be removed, the greater the effectiveness of the plasma will be in removing the same stain. In the case that the outlet from the discharge gap is positioned relatively far from the stain to be removed, the effects of the plasma issuing from the discharge gap recombining with the surrounding air would cause the proportional amount of active species reaching the fabric to decrease to a considerable extent, thereby sensibly

reducing the stain removal effect.

The user, who is forced to operate the device with the aid of the handle of the flatiron, is therefore not capable of correctly positioning the outlet from the discharge gap in proximity of the stain to be treated, since the flatiron and the outer structure of the same plasma cleaning device act as a hindrance in this connection by at least partially concealing both the outlet from the discharge gap, which is provided on the lower portion of the plasma cleaning device, and the fabric lying thereunder.

A further drawback of the device disclosed in JP2005224757 lies in the fact that the electrodes forming the discharge gap are not electrically insulated to any adequate extent and, when the flatiron is applied on to the plasma cleaning device, the metal hotplate of the flatiron comes to lie dangerously close to the electrodes at the risk of giving rise to arcing and flashover occurrences on the same hotplate. Yet another drawback of the device disclosed in JP2005224757 derives from the fact that supplying the discharge gap with the steam generated by the flatiron proves scarcely effective and - moreover - rather complicated. In fact, for the steam to be enabled to reach the discharge gap, a kind of chamber is provided between the portion of hotplate which the steam is issuing from and an upper portion of the plasma cleaning device, where there is provided the inlet to the discharge gap. Such solution, however, does not ensure any adequate flow of steam through the discharge gap, with the result of a low generation of plasma and, as a consequence, a low generation rate of active species. For a high generation rate of active species to be ensured, it is in fact important to have a consistent flow of aeriform or gaseous medium flowing through the discharge gap.

A further drawback yet of the above-cited prior art derives from the fact that, as the plasma cleaning device is being used, the high-voltage AC generator is due to stay constantly in an energized state, unless the power-supply plug is disconnected from the power-supply line. For instance, the high-voltage AC generator would in fact remain in an energized state throughout the period of time required for the user to succeed in identifying the exact position of each single stain on the fabric to be cleaned and moving the outlet of the discharge gap from a stain to the next one. It can be readily appreciated

that, during these time intervals when the device is not really used to do its actual job, this leads to energy being wasted and ozone being generated to no effective avail.

It is therefore a main object of the present invention to provide a fabric cleaning apparatus, which is effective in doing away with the above-noted drawbacks of the cited prior art.

Within this general object, it is a further purpose of the present invention to provide a fabric cleaning apparatus of the above-mentioned kind, which is most effective in removing organic-soil stains from the fabrics, is simple to manufacture and convenient to use.

According to the present invention, these aims, along with further ones that will become apparent from the following disclosure, are reached in a fabric cleaning apparatus that incorporates the features as defined and recited in the claims appended hereto.

Features and advantages of the present invention will anyway be more readily understood from the description that is given below by way of non-limiting example with reference to the accompanying drawings, in which:

- Figure 1 is a perspective view of a fabric cleaning apparatus according to the present invention, as viewed with the casing thereof shown in a partially cut-away representation;

- Figure 2 is an enlarged side view of the discharge gap of the fabric cleaning apparatus shown in Figure 1 , wherein the casing of the apparatus is shown in a see-through representation;

- Figure 3 is a perspective view of a fabric cleaning apparatus according to another embodiment of the present invention, as viewed with the casing thereof shown in a partially cut-away representation;

- Figure 4 is a perspective view of a fabric cleaning apparatus according to a further embodiment of the present invention, as viewed with the casing thereof shown in a partially cut-away representation;

- Figure 5 is a side elevational cross-sectional view of the apparatus shown in Figure 4;

- Figure 6 is a front elevational cross-sectional view of the apparatus shown in Figure 4.

With reference to the above-cited Figures, the fabric cleaning apparatus, as generally indicated with the reference numeral 1 , comprises at least a dielectric-barrier discharge assembly 2 adapted to generate plasma at atmospheric pressure for decomposing and removing organic-soil stains from the fabrics to be cleaned.

The dielectric-barrier discharge assembly includes a high-voltage electrode 3, a counter-electrode 4, and at least a dielectric barrier 5 defining a discharge gap 6 between said electrodes 3, 4.

The apparatus 1 comprises a high-voltage AC generator 7 connected to said high- voltage electrode 3, as well as fluid supplying means provided to supply the discharge gap 6 with a flow of aeriform medium.

The apparatus 1 further comprises an electrically insulating outer casing 8 accommodating said dielectric-barrier discharge assembly 2 and provided with an outlet nozzle 9 that is fluidly connected with said discharge gap 6, said casing 8 being adapted to be seized and held by a user so as to enable the latter to position said outlet nozzle 9 close possible to a stained portion of the fabric to be cleaned; switching means 10 are provided on said outer casing 8 to switch on and off said high- voltage AC generator 7 and actuate said fluid supplying means.

The outer casing 8 is comprised of a containment body that is so shaped as to be able to be seized and held with a single hand by a user, who is in this way capable of

directing in a localized manner the flow of plasma issuing from the outlet nozzle 9 onto ^• an organic-soil stain 11 that needs to be removed from a fabric 12. In this connection, the outer casing 8 is preferably comprised of an elongated hollow body that extends in a longitudinal direction and defines, at an end portion thereof, a possibly tapered outlet port forming the outlet nozzle 9 provided to direct the plasma onto the stained fabric.

The high-voltage electrode 3 and the counter-electrode 4 are provided in a mutually facing arrangement duly spaced from each other, whereas the dielectric barrier 5, in the particular embodiment being discussed, comprises a coating layer that covers the surface of the high-voltage electrode 3 facing the counter-electrode 4, so as to provide, between the electrodes, the discharge gap 6 where the plasma is generated. In practice, the discharge gap 6 defines a fluid passage comprising an inlet section 13, which is fluidly connected with the fluid supplying means to receive the aeriform medium, and an outlet section 14, which is arranged in proximity of the outlet nozzle 9 of the outer casing 8, from which the plasma being generated along the discharge gap 6 issues to be directed at hitting an organic-soil stain 11 that needs being removed from a fabric 12, such as a garment or clothing item to be cleaned.

The high-voltage AC generator 7, which is connected to the high- voltage electrode 3, is accommodated inside the casing 8.

Advantageously, the counter-electrode 4 is connected to ground.

In a preferred manner, the high-voltage AC generator 7 is connected to a power supply 15, which is also arranged within the casing 8.

The power supply 15 preferably comprises a storage battery, such as in particular a rechargeable storage battery, provided to supply the generator in an autonomous manner.

Alternatively, the high-voltage AC generator 7 may be supplied from the power- supply line or a low-voltage power-supply source.

The fluid supplying means comprise a fluid-carrying conduit 16, which is provided inside the casing 8 to convey an air stream flowing in from the ambient surrounding the hand-held outer casing 8 of the apparatus towards the inlet section 13. This fluid- carrying conduit 16 may even be provided integrally in a properly shaped and conformed inner portion of the casing 8.

The fluid-carrying conduit 16 includes an inlet port 17 that is fluidly connected with the outside ambient surrounding the outer casing 8, as well as an outlet port 18 that is fluidly connected with the inlet section 13 of the discharge gap 6.

In addition, the fluid supplying means comprise at least a fan or impeller 19, which is arranged inside the outer casing 8 so as to be adapted to force an air stream through the fluid-carrying conduit 16.

In particular, the fan 19 is adapted to take in air from the outside ambient surrounding the casing 8 through the inlet port 17 of the fluid-carrying conduit 16, and to convey this air towards the outlet port 18 of the same fluid-carrying conduit 16, from which it is then blown into the inlet section 13 of the discharge gap 6.

Also the motor means used to drive the fan are arranged within the casing 8 and are preferably energized from the rechargeable storage battery.

In particular, the fan 19 is arranged along the fluid-carrying conduit 16, inside the same, between the inlet port 17 and the outlet port 18 thereof.

The switching means 10 comprise a push-button, which is actuatably provided on the outer casing 8 to control circuit means connected to the power supply 15 in view of energizing/de-energizing the high-voltage electrode 3 and switching on/off the fan 19 as desired by the user.

Advantageously, the switching means 10 are such as to enable the high-voltage electrode 3 to be energized and the fan 19 to be switched on at the same time and, conversely, the high-voltage electrode 3 to be de-energized and the fan 19 to be

switched off at the same time, in such a manner as to minimize the energy usage of the apparatus 1 , as well as to limit plasma generation to the sole period of time as strictly necessary for the stain to be removed.

In practice, when the need arises for a user to remove an organic-soil stain from a clothing item, or the like, it just takes for the outlet nozzle 9 of the outer casing 8 to be brought as close as possible to the stain 11 and the push-button of the switching means 10 to be pressed down.

The fan 19, as switched on by said push-button being so actuated, forces a continuous air stream to flow into and through the discharge gap 6, where the electric field produced by the high-voltage electrode 3 - which is in turn energized through the switching means 10 - brings about a sequence of micro-discharges across the dielectric barrier 5, which cause the air stream flowing through the discharge gap 6 to ionize, thereby generating highly reactive molecular or atomic particles, which chemically bind to the organic matters in the stain to thereby form volatile compounds or oxidize such organic matters. When the stain is eventually removed or oxidized, all it takes is to press again the above-cited push-button to de-energize the high-voltage electrode and - at the same time - switch off the fan.

The possibility is therefore given for each single stain to be treated selectively and individually, thereby limiting the energy usage and the generation of the highly reactive particles to such amount and period of time as strictly necessary for a stain to be removed.

In a particularly preferred embodiment, the dielectric barrier 5 is arranged to cover a surface of the high-voltage electrode 3 that is provided at the outlet section 14 of the discharge gap 6 and faces the outlet nozzle 9 of the outer casing 8, so as to form an auxiliary discharge gap 20 with an auxiliary ground electrode 21 provided outside the casing 8 and adapted to support the stained fabric in proximity of the outlet nozzle 9.

In practice, the auxiliary discharge gap 20 is created through the use of an auxiliary ground electrode 21 , which may consist of either any metal surface that is readily

available to the user or a metal surface that is specially provided jointly with the fabric cleaning apparatus according to the present invention. The stained portion of the fabric that needs being treated to cleaning purposes is then placed on such auxiliary ground electrode 21.

The auxiliary discharge gap 20 is formed by appropriately approaching the outlet nozzle 9 of the outer casing 8 close to the stain 11 on the fabric 12, so as to bring the surface of the high-voltage electrode 3, which is facing the outlet nozzle 9 of the casing

8, and which is covered by the dielectric barrier 5, as close as possible to the auxiliary ground electrode 21 supporting the stained fabric that lies therebelow.

When the high-voltage electrode 6 is then energized, micro-discharges are produced even in the portion of the dielectric barrier 5 that is facing the auxiliary ground electrode

21 , as well as within the auxiliary discharge gap 20.

Together with the discharge gap 6, the auxiliary discharge gap 20 allows a generation rate of highly reactive particles to be obtained, which is clearly higher than the generation rate that is usually obtained with the use of the discharge gap 6 alone.

As a result, a greater amount of highly reactive particles are therefore made available on the surface of the stained fabric to chemically react with the organic substances forming the stain to be removed, thereby enhancing the effectiveness of the cleaning process.

In a further embodiment of the present invention, as illustrated in Figure 3, the fluid supplying means comprise a reservoir 22 containing a compressed medium, which is connected to the fluid-carrying conduit 16 to supply the discharge gap 6 with a continuous flow of aeriform medium. In an advantageous manner, an additional conduit

23, preferably a flexible tube, is provided to fluidly connect the reservoir 22 with the fluid-carrying conduit 16 at the inlet port 17.

This additional conduit 23 may of course be provided in a single-piece, unitary construction with the fluid-carrying conduit 16. In particular, the additional conduit 23 may be formed by an extension of the fluid-carrying conduit 16 starting from the inlet port 17.

The reservoir 22, e.g. a gas bottle or a gas cylinder, advantageously contains a mixture of compressed media (possibly including air and water vapour) or highly volatile substances, which, when ionized, dissociated and excited within the discharge gap 6, produce and deliver extremely reactive particles adapted to either combine with the organic substances staining the fabric to form volatile compounds therewith, or to oxidize such organic substances.

It has been experimentally found that, among various media investigated, the substances that most of all seem to suit this application include alcohols (R-OH), which deliver OH ^" groups; formic acid (HCOOH) or formaldehyde (HCOH), which deliver OH ^" ,

H ⁺ , O atomic; freons, which deliver Cl ^" , F ^" , Br ^" ; ammonia (NH ₃ ) and hydrazine (N ₂ H ₄ ), which deliver amino groups. Advantageously, use can be made of bottles or cylinders, which may contain different mixtures of compressed media, or even a single specific compressed aeriform substance, depending on the type of organic soil to be removed from the fabric.

The fluid supplying means further comprise valve means 24 provided to control and adjust the flow of the gaseous stream passing through the outlet port 18 of the fluid- carrying conduit 16 and, therefore, to adjust the flow that passes through the discharge gap 6.

These valve means 24 are in fact adapted to establish a fluid communication, or cut off said fluid communication, as the case may be, between the reservoir 22 containing the pressurized fluid mixture and the outlet port 18 of the fluid-carrying conduit 16.

The switching means 10, which - as already mentioned afore - are provided to be actuatable by the user on the outer casing 8 of the apparatus, are adapted to switch the valve means 24 on and off, i.e. into opening and closing, as needed.

In particular, with the same switching means it is possible for the high-voltage electrode 3 to be energized and, at the ^' same time, the valve means 24 to be switched into opening, in the same manner as already described hereinbefore for the fan 19.

Preferably, the valve means 24 are housed in the casing 8 and, in an advantageous manner, are provided inside the fluid-carrying conduit 16.

The above-mentioned valve means may for instance be comprised of an electromagnetic valve powered from the power supply 15 and connected to the switching means 10.

In a yet further embodiment of the present invention, as illustrated in the Figures 4-6, the dielectric-barrier discharge assembly 2 comprises a dielectric barrier 35 that surrounds, i.e. encloses a counter-electrode 34 without contacting it, wherein said counter-electrode 34 is arranged within the dielectric barrier 35, and comprises a high- voltage electrode 33 in the form of a wire that is spirally wound on the outside of the dielectric barrier 35, in contact thereto.

Between the counter-electrode 34 and the dielectric barrier 35 there is therefore formed a discharge gap 36, which is adapted to be supplied with a flow of aeriform medium by the fluid supplying means.

In the exemplary embodiment being described, the dielectric barrier 35 comprises a hollow cylinder of a dielectric material, preferably of glass, in the interior of which there is coaxially provided the counter-electrode 34, which is in turn formed of a rod-like body extending along the axis of the cylinder of the dielectric element 25 and is connected to ground. The high-voltage electrode 33 comprises an electrically conductive wire that is spirally wound round the outer surface of the cylinder forming the dielectric barrier 35. The annular gap comprised between the dielectric barrier 35 and the counter-electrode 34 forms the discharge gap 36, through which there flows the aeriform medium undergoing ionization.

Owing to its having a number of sharp or markedly curved points with a very high potential gradient, the wire-wound high-voltage electrode 33 is effective in favouring the formation of micro-discharges across the dielectric barrier as compared with a low- curvature or flat electrode, such as a plate, thereby enhancing plasma generation.

In practice, the discharge gap 36 defines a passage for a medium flow comprising an inlet section 13, which is fluidly connected with the fluid supplying means to receive the aeriform medium, and an outlet section 14, which is arranged in proximity of the outlet nozzle 9 of the outer casing 8, from which the plasma being generated along the discharge gap 6 issues to be directed at hitting an organic-soil stain 11 that needs being removed from a fabric 12, such as a garment or clothing item to be cleaned.

The electrically insulating outer casing 8 surrounds and contains the dielectric- barrier discharge assembly 2, whereas the high-voltage AC generator 7 and the fluid supplying means are provided outside the casing in a proper separate station 37.

As a result, both the dielectric-barrier discharge assembly 2 and the electrically insulating outer casing 8 can be given an extremely compact size, just like a pen or the like.

The separate station 37 accommodates the high-voltage AC generator 7, which is connected - via appropriate electric cables - to the high-voltage electrode 33. The high- voltage AC generator 7 may be supplied directly from the power-supply line, a low- voltage power-supply source, or a power supply 15 specially provided inside the station 37, preferably in the form of a storage battery, in particular a rechargeable storage battery.

The fluid supplying means comprise a reservoir 22, which is arranged inside the station 37 to contain a compressed medium, and is fluidly connected to the discharge gap 36.

A delivery conduit 38, preferably a flexible tube, is provided between the station 37 and the outer casing 8 to fluidly connect the reservoir 22 to the inlet section 13 of the discharge gap 36.

Advantageously, the reservoir, which may for example be a gas bottle or gas cylinder, contains mixture of compressed media (possibly including air and water vapour) or highly volatile substances, which, when ionized, dissociated and excited

within the discharge gap 36, produce and deliver extremely reactive particles adapted to either combine with the organic substances staining the fabric so as to form volatile compounds therewith, or to oxidize such organic substances.

It has been experimentally found that, among various media investigated, the substances that most of all seem to suit this application include alcohols (R-OH) ₁ which deliver OH ^" groups; formic acid (HCOOH) or formaldehyde (HCOH), which deliver OH ^" , H ⁺ , O atomic; freons, which deliver Cl ^" , F ^" , Br ^" ; ammonia (NH ₃ ) and hydrazine (N ₂ H ₄ ), which deliver amino groups. Advantageously, use can be made of bottles or cylinders, which may contain different mixtures of compressed media, or even a single specific compressed aeriform substance, depending on the type of organic soil to be removed from the fabric.

The fluid supplying means further comprise valve means 24 provided to control and adjust the flow of the gaseous stream passing through the delivery conduit 38 and, therefore, to adjust the flow that passes through the discharge gap 36.

These valve means 24 are in fact adapted to establish a fluid communication, or cut off said fluid communication, as the case may be, between the reservoir 22 containing the pressurized fluid mixture and the inlet section 13 of the discharge gap 36.

As already mentioned afore, the switching means 10, which are provided to be actuatable by the user on the outer casing 8 of the apparatus, are adapted to switch the valve means 24 on and off, i.e. into opening and closing, as needed.

In particular, with the same switching means it is possible for the high-voltage electrode 33 to be energized and, at the same time, the valve means 24 to be operated into opening.

Preferably, the valve means 24 are housed in the station 37 and may for instance be comprised of an electromagnetic valve powered from the power supply 15 and connected to the switching means 10.

In an alternative embodiment, the fluid supplying means comprise a fan, or impeller, provided in the station 37 and adapted to force an air stream to flow along the delivery conduit 38 and, as a result, through the inlet section 13 of del dielectric-barrier discharge assembly 2.

It has been experimentally found that a voltage situated within the range from 2.5 to 3.0 kV used to supply the high-voltage electrode 3, 33 will ensure the lowest formation of ozone in the plasma, so as to prevent the risk of dangerous ozone concentrations forming during the operation of the device. Further, a low concentration of ozone avoids the degradation of plastics and rubbers.

Conclusively, it can therefore be stated that the fabric cleaning apparatus according to the present invention ensures an effective removal of organic-soil stains in an extremely simple and convenient manner, thereby doing away with the serious drawbacks shared by prior-art devices.