DEVICE FOR CLEANING AN AIR FILTER"

DESCRIPTION :

The present invention relates to a washing/drying machine, i . e. machines for household, industrial or commercial use intended for washing and drying laundry in general .

These machines, therefore, have some elements in common with washing machines, e. g. the washing tub or chamber that houses a rotary b asket or drum; the clothing or, more generally, the laundry to be treated i s loaded into the basket through a door, which may be located either at the front or at the top, depending on the machine type.

The rotation of the basket keeps the load moving during the washing and/or drying phases, when the tub i s supplied with water and air, respectively .

In the course of the working cycle of the washing/drying machine, the load, consi sting of clothing, such as trousers, T -shirts and underwear, or cloths and the like, normally releases filaments that are evacuated through the water drain.

Thi s occurs in a simple and direct manner during the wash, in that water i s supplied and drained several times for washing the laundry with detergents, rinsing it, etc. , so that the filaments released by the fabrics are removed from the laundry and evacuated together with the water being drained.

When laundry i s being dried, instead, the filamentous wads generated by the clothes rubbing against the inner wall of the basket (the quantity of which increases as humidity decreases) are dragged by the air flow that circulates in the machine and laps the l aundry items contained in the basket for drying them, but cannot be evacuated in the same way because no water i s supplied into the basket during the drying cycle.

As can be easily understood, the drying air must be cyclically filtered to prevent the fan and the associated electric heating resi stor, included in the air circuit, from suffering damage.

To thi s end, it i s known to take air from the washing/drying tub, filter it, reduce the humidity thereof, and introduce it again into the tub .

The air is filtered as it flows through a filter comprising a grid or net made of metal, plastic or the like, arranged on a wall of the washing/drying chamber (in particular, on the back wall, at the outlet section towards the drying circuit), the mesh of whi ch i s sufficiently tight to trap the filaments released by the fabrics; it can b e easily understood that the filamentous wads progressively depositing onto the filter will reduce the air passage section thereof and will cause load losses that will slow down the air flow, resulting in a general reduction of the effici ency of the laundry drying cycle.

The present invention aims at overcoming thi s problem that limits the state of the art.

Therefore, the technical problem at the b asi s of the invention i s to provide a washing/drying machine having such structural and operating characteri stics that keep regular and efficient air filtering conditions, so as to ensure the execution of a correct laundry drying cycle.

The idea that solves thi s problem i s to remove from the filter the filaments deposited thereon by the air during the laundry drying cycle : in thi s way, it i s possibl e to prevent the filter from getting clogged quickly, thus keeping it efficient for a longer time and reducing the load losses and the resulting higher energy consumption of the washing/drying machine.

According to the invention, thi s i s achieved by spraying water onto the filter, in particular on the side thereof where air-borne filaments, fibres, etc. get deposited.

The features of the invention as a whole are specifically set out in the claims appended to thi s description.

Such features will become more apparent from the following description of a preferred but non-limiting example of embodiment thereof as shown in the annexed drawings, wherein :

- Fig. 1 i s a perspective view of a washing/drying machine according to the invention;

- Fig. 2 i s a perspective view of the washing/drying tub or chamber of the machine of Fig. 1 , with the associated drying circuit;

- Fig. 3 is a perspective view of the washing/drying tub of the machine of Fig. 1 from a different angle than Fig. 2;

- Fig. 4 shows the tub of Figures 2 and 3 with a part thereof removed to make the internal parts vi sible;

- Fig. 5 shows a detail of the filter cleaning device applied to the washing/drying machine of the preceding figures;

- Fig. 6 shows a schematic view of the filter cleaning device of the preceding figures;

- Figs. 7 and 8 show respective variants of the detail of Fig. 5.

With reference to the above-li sted drawings, reference numeral 1 designates as a whole a washing/drying machine in accordance with the present invention, which compri ses an external structure 2 sub stantially shaped like a parallelepiped cabinet, with a front panel 3 equipped with user control s (e .g. push-buttons, knob s, etc. ) and various indicators, lamps, di splay s, or other means such as detergent drawers, useful for the control and operation of the machine 1 .

It i s worth pointing out that reference will b e made in thi s description, for simplicity and cl arity, only to those elements of the washing/drying machine 1 which are useful for understanding the present invention; for more information, reference can b e made to the prior art, e. g. washing/drying machines created by the present Applicant or described in patent applicati ons filed by the latter on thi s matter, such as European patent applications EP 21 16647, EP 228 108 1 , EP 1907616, EP 1775368, EP 1647621 and more, which are integrally recalled herein, and the contents of which should be considered as incorporated in the present description because applicable thereto.

At the front of the cabinet 2 there i s the load opening 4 of the washing/drying machine, which i s closed by a door 5.

The cabinet 2 of the washing/drying machine internally houses a washing/drying chamber or tub 1 0, in which a basket 1 1 for loading laundry to be treated i s supported in a per se known manner. The chamber or tub 10 is intended for washing/drying laundry, in that a machine like the one considered herein performs a dual function as a water tub during the washing cycle and as a drying chamber during the drying cycle.

The basket 1 1 has the typical cylindrical drum -like configuration, with a perforated side wall allowing water to fl ow through, as vi sible in Figures 1 and 4, and is equipped with inner paddles or lifters 12 for stirring the load while rotating when the machine 1 i s in operation.

The chamber 10 compri ses a sub stanti ally cylindrical skirt or side wall 1 5 (possibly slightly convex), closed at the rear by a back wall 16, whil e at the front it has a collar 17 on which a gasket 1 8 i s applied, sealing the opening 4 of the cabinet 2 of the washing/drying machine 1 .

Outside the chamb er 10 a drying air circuit 20 i s arranged, which compri ses an intake channel 21 (al so acting as a condenser) and a delivery channel 22, between which a fan 23 i s arranged for air circulation.

In particular, the delivery channel 22 extends from the collar 17 of the chamber 10 to the fan 23 , whereas the intake channel 21 extends from the fan 23 to an intake port formed in the b ack wall 16 of the chamber 10, where there i s a filter 25 for the filaments borne by the drying air. The filter 25 i s slightly eccentric relative to the axi s of rotation of the basket 1 1 , where the support and/or rotation means of the basket 1 1 , such as shaft, bearings, pulleys, etc. (not shown in the drawings because they are per se known) are applied to the back wall 16 of the chamber 10.

The filter 25 may be designed in any suitable manner, e .g. with a metal or plastic grid or net having a mesh suitable for trapping the filaments released by the laundry being treated in the washing/drying machine 1 ; the mesh may have a polygonal (e. g. square, rectangular, hexagonal) or circular shape, etc. , the mesh size b eing smaller than 1 mm .

In the emb odiment of Figures 5 and 6, the filter 25 i s applied to the b ack wall 16 of the tub 10, at an aperture 14 in the wall 16, and extends into the intake duct 2 1 .

With reference to Figure 7, the filter 25 shown therein compri ses a structure 26 mainly consi sting of a sub stantially cylindrical side wall closed at the front by a filtering wall 27 arranged perpendicular to the cylindrical wall 26.

The structure 26 i s applied to the aperture 14 of the back wall, being al so equipped with appendices 32 for fitting into the aperture 14 of the back wall 16 of the tub 10.

In accordance with the invention, the structure of the filter 25 compri ses the nozzles 3 1 , which in thi s example are advantageously mounted to a support spi der 33 located on the front wall of the cylindri cal structure of the filter, where there i s al so the filtering wall 27.

The latter is divided by the spi der 33 into four sectors of a circle having a central angle of 90° : their number may however vary, whether smaller or greater than four, if different configurations are adopted, other than the spider-shaped one, for the support element 33 where the nozzles are arranged. Thus, for example, there may be three sectors having a central angle of 120° when using a three-arm sunburst-pattern element, or six sectors when using a six -arm sunburst-pattern element, and so on.

What it important i s that the nozzles 3 1 arranged on the spider-shaped support 32 will spray water onto the filtering sectors or wall s 27 in a manner sub stantially tangential thereto, as previously explained.

For thi s purpose, the filter 25 i s axially equipped with a fitting 30 connected to a hydraulic circuit compri sing, among other things, an intake tap or electrovalve 35 , a recirculation branch 36, and a pump 38. In particular, the intake tap or electrovalve 35 i s connected to or anyway associated with the water mains that supplies water to the washing/drying machine 1 , which i s provided with a branch 36 for recirculating the water extracted from the bottom of the washing/drying chamber 10 through a first drain 37.

The connection between the electrovalve 35 and the nozzles 3 1 may or may not include an air break, and the j ets from the nozzles 3 1 must have sufficient pressure to effectively hit the filter 25 and its side wall s 27. The cylindrical wall 26 with the nozzles 3 1 i s at least partly housed in the intake and condensation channel 2 1 , which i s secured to the back wall 16 of the washing chamber 10; advantageously, in the lower part of the intake channel 21 there i s a second drain 47 for the water sprayed by the nozzles 3 1 (as well as for the condensed water created by the condenser in the channel 21 ).

Thus, the water collected by gravity on the bottom of the channel 21 will be evacuated into the recirculation branch 36; in thi s regard, it must be pointed out that the vertical arrangement of the intake duct 21 , resulting from its application to the back wall 16, will promote the evacuation by gravity from the drain 47 towards the recirculation branch 36 .

To thi s end, in accordance with a preferred embodiment, the device 5 for cleaning the filter 25 allows the water, especially the condensed water generated during the laundry drying stage, to be recirculated into the branch 36 by a pump 38 that gives it sufficient pressure to clean the filter 25.

In this case, along the hydraulic circuit there i s al so a diverting valve 39, which can direct the flow either towards the drain S or into the recirculation branch 36, to be then delivered again to the nozzles 3 1 . In fact, when the water is contaminated by filaments, the valve 39 will direct it towards the drain S, otherwi se it will be reused for a filter cleaning cycle .

The filter 25 i s install ed at the aperture 14 on the b ack 1 6 of the washing chamb er 10. Tightness i s preferably ensured by means of a gasket 29. In particular, the filter 25 i s applied in such a way that the filtering wall 27 with the nozzles 3 1 will face towards the inside of the chamber 10, so that, when cleaning i s activated, the nozzles 3 1 will spray water against the filtering wall 27 on the side thereof facing towards the chamber 10. Preferably, the water j ets are emitted by the nozzles 3 1 in a direction tangential to the sectors of the filtering wall 27, and remove the filaments deposited thereon through the effect of the hydrodynami c action of the water; in thi s regard, it must be pointed out that the spider 33 i s slightly lower than the filtering wall 27 : therefore, the supply pressure of the nozzles 3 1 will be relatively low, so that the water can drip on the filtering wall .

In the variant shown in Figure 8, where the item s are designated by the same numbers with the addition of an apostrophe, the pressure of the water sprayed by the nozzles 3 can b e higher because the spider 33 ' protrudes relative to the filtering wall 27 ' : in this case, the water j ets will be directed against the filtering wall 27 ' of the filter 25 ' at a small angle of incidence .

Filaments will al so be removed through the effect of the greater hydrodynamic force offered by thi s solution.

It must nevertheless be pointed out that in both of the embodiments shown in Figures 7 and 8 water i s sprayed onto the filtering wall 27 or 27 ' , respectively, on the side thereof facing towards the inside of the tub 10, i . e. the side whereon filaments borne by the laundry drying air get deposited.

It follows that, even if the water fed to the nozzles comes from outside the tub 10, i . e. from the mains via the intake tap 35 or from the recircul ation branch 36, it will then be sprayed by the nozzles 3 1 , 3 Γ onto that side of the filtering wall s 27, 27 ' which faces towards the inside of the tub, or anyway on which the filaments coming from the inside of the tub get deposited when air is taken in.

Therefore, the filaments removed by the water will fall into the tub 10 or onto the bottom of the intake channel 21, so that they can be easily removed through the drain S.

Finally, it should be noted that the variants of the filter 25, 25' and of the nozzles 31, 31', which spray water as described, can be combined together in order to create a further variant; in this case, there will be a protruding spider 33 with nozzles 31 and 31' associated therewith as explained above.

In the light of the above explanation it is possible to understand the operation of the washing/drying machine 1 according to the invention, especially as concerns the device 5 for cleaning the filter 25, whereas as regards the washing and drying functions the following description will only tackle those aspects that may be useful for understanding the invention; for further details, therefore, reference should be made to the operation of the washing/drying machines known in the art.

When, during an operating cycle of the washing/drying machine, the filter 25 becomes clogged with filaments released by the laundry being treated, the cleaning device 5 will be activated to spray water from the nozzles 31 against the filtering walls 27 of the filter 25, so as to remove the filaments deposited thereon.

In particular, as indicated by the arrows in Figures 7 and 8, the nozzles 31 spray water into the filter 25, preferably directing the jet in a manner substantially tangential to the filtering walls 27 or anyway at a small angle of incidence relative to the surface of the latter; in thi s description and in the appended clai ms, the angle of incidence refers to the angl e defined by the direction of a water j et and by the profile of the filtering wall 27 against which the j et i s directed.

Thi s way of spraying water promotes the removal of the filaments deposited on the filtering wall s 27, while at the same time avoiding the application of excessive hydrodynamic pressure onto them, which might otherwi se damage them, as it would happen if the j et were directed perpendicularly to the filtering surface.

It should be noted, in fact, that when the filtering surfaces 27 are thin (e.g. made out of braided wires or synthetic fabri cs) and/or have a small and thick mesh, the action of a j et directed perpendicularly against them might deform them because of its hydrodynamic pressure, thereby j eopardizing their efficiency and reliability .

It should al so be highlighted that, in accordance with the present invention, the water j ets sprayed by the nozzles are directed inside the filter 25, i . e. the part thereof whereon filaments get deposited : thi s ensures a more effective removal action, because the water j ets will directly act upon the filaments.

In thi s respect, it must be pointed out that the Applicant has been able to verify the effectiveness of thi s solution with water j ets directed inside the filter, compared to the solution wherein the water j ets are external, i . e. water i s sprayed onto the side of the filtering wall s opposite to that on which filaments get deposited. Once removed, the filaments are evacuated along with the cl eaning water through the drain 37 of the washing chamber 10.

Note that, depending on the operating step s of the washing/drying machine 1 , the cleaning water may b e water coming from the household mains, supplied through the tap 35 , or recirculated water coming from the branch 36 that coll ects the condensed water created by the drying air in the intake duct 21 .

The management of the filter cleaning water, i . e . mains water or recirculated water, essentially depends on the mode in which the filter i s to be cleaned.

For exampl e, the cleaning device 5 may be made to operate continuously during the drying step or, in order to optimize water consumption, it may operate in an intermittent and/or impul sive manner, in which case the device 5 will only be activated during particular time interval s in the course of the drying step, or, alternatively, in the course of one or more sub step s specifically dedicated to the cleaning of the filter 25.

Preferably, the cleaning device 5 i s turned on at the end of a drying cycle, or anyway before a new wash cycle begins; in such circumstances, with the machine empty or with a small l oad in the basket 1 1 , water will be supplied to the nozzles 3 1 from the mains when the intake tap 35 i s opened.

According to a preferred mode of controlling the devi ce 5 , thi s will be activated when the relative humidity in the chamber 1 0 fall s below a preset threshold. It will b e only from then onwards, in fact, that filaments, fibres, lint or bobbles will be released from the l aundry in a significant amount. For example, one may conceive a pul sed activation of the device 5 when a residual humidity of 1 0% i s reached in the chamber 1 0, with a duty cycl e depending on the pressure and/or fl ow of the water suppli ed to the nozzles 3 1 . The residual humidity in the tub can be sensed in a known manner, e.g. by applying the teachings of patent application GB21 54721 A.

The filter will then be washed with mains water, which will then be evacuated from the tub bottom through the drain S ; in thi s case, the diverting valve 39 will send the nozzle washing water directly towards the drain.

If on the contrary no filaments are found in the water, the latter can be reused for washing the filter 25 ; thi s working cycle may be carried out either in a programmed manner, i . e. with a certain ti ming or after a certain number of drying cycles of the machine 1 , or in a controlled manner, through the use of suitable sensors.

For example, let us consider the case wherein one wants to detect any leakage in the circuit 20 of the drying air; thi s detection can be made either by means of suitable pressure sensors or by reading the values of the electric power ab sorbed by the electric motor that drives the fan 23 . When the ab sorbed power reaches certain preset level s, thi s means that the filter i s clogged and requires the removal of the filaments deposited thereon. As an alternative, the condition of the filter 25 can b e controlled by means of optical sensors : the presence of filaments deposited on the filter will prevent the passage of luminous signal s, and thi s condition can be detected by means of optical sensors, so that a cleaning cycle can then be started as explained above.

Of course, the invention may be subj ect to other variations with respect to the description provided so far.

In fact, although the example shown in the drawings i s structurally and functionally simple, thus being preferable because it i s economically advantageous, the use of different solutions should not b e excluded as concerns the nozzles and their supply sy stem .