EP2642012B1

EP2642012B1 - Laundry machine and method of laundry treatment in a laundry machine

Info

Publication number: EP2642012B1
Application number: EP12160679.2A
Authority: EP
Inventors: Alberto Bison; Maurizio Ugel; Massimiliano Vignocchi
Original assignee: Electrolux Home Products Corp NV
Current assignee: Electrolux Home Products Corp NV
Priority date: 2012-03-22
Filing date: 2012-03-22
Publication date: 2019-05-08
Anticipated expiration: 2032-03-22
Also published as: WO2013139686A1; PL2642012T3; AU2013234488A1; EP2642012A1; CN104204331A; CN104204331B

Description

The present invention relates to a laundry machine and to a method of laundry treatment in a laundry machine.
In the present application the laundry machine can be a washing machine, a drying machine or a washing-drying machine (i.e. a washing machine which can both wash and dry the laundry).
In the present application the expressions "treatment" and "treating" in relation to laundry are used to indicate laundry treatments as washing, rinsing, drying, spin-drying, steam-treating and/or similar.
It is known in the art to use a steam generator in a laundry machine for supplying steam into the washing and/or drying drum in order, for example, to subject the cloths to a steam-refreshing cycle or to eliminate (or reduce) creasing of the cloths after a drying or spin-drying cycle.
EP 1 970 482 discloses a home laundry drier with a closed circuit hot-air generator comprising a heat exchanger, a heater, a water tank, an auxiliary heater for converting water in the tank into steam and a process water recovery circuit, which extracts the water formed in a heat exchanger by condensation of the surplus moisture in the air flow from the drying tub, and feeds said water into the water tank for use in producing steam.
EP 2 014 820 discloses a home laundry drier with a closed circuit hot-air generator and a steam generator. The steam generator has an electric boiler, a demineralised-water reservoir and a lint filter, the demineralised-water reservoir receiving demineralised water from the water canister of a heat exchanger of the hot-air generator via a water drain circuit.
The Applicant observes that the steam generators described by the above mentioned documents generate steam by means of a boiler. However, to prevent deposits of lime scale, which could impair the operation of the steam generator, the steam generator has to be refilled with demineralised water. In order to avoid manual refilling of demineralised water, the above mentioned documents disclose to use the demineralised water formed by condensation in the heat exchanger of the closed circuit hot-air generator. However, this water is often dirty with fluff and/or lint that may cause damages to the steam generator. In order to keep the fluff and/or lint out of the steam generator water reservoir, EP 2 014 820 discloses the use of a lint filter located upstream the steam generator water reservoir and means for determining clogging of the lint filter. However, the Applicant observes that this complicates the design and construction of the laundry machine.
In addition, the Applicant observes that in washing machines wherein a hot-air generator is not present, or in drying machines equipped with an open circuit hot-air generator (as disclosed, for example by EP 1 995 371 ), demineralised water has to be manually refilled by the user. This makes the use of the machine unpleasant to the user. In addition, when tap water is used, notwithstanding the instructions of using demineralised water, deposits of lime scale can be generated, which could impair operation of the steam generator. This affects the lifetime and reliability of the steam generator.
US 2009165327 discloses a device and process for conveniently removing wrinkles from dried clothes. The device includes an outer shell enclosing a core of water absorbent material. The device may be spherical, cubic, or be in other regular or irregular geometric shapes, having a finish that would not damage or affect the tumbling of clothes in the dryer. The foam material in the shell is saturated with water prior to tossing into the clothes dryer with the clothes to be de-wrinkled. Moisture from the foam material in the shell is introduced into the dryer chamber from the dryer heat, which relaxes wrinkles on clothing
It is an object of the invention to provide an alternative laundry machine with a steam generator.
It is a further object of the invention to provide an improved laundry machine with a steam generator of comparatively easy design and construction, high reliability and long lifetime.
It is another object of the invention to provide an alternative laundry machine with a steam generator that can be operated without demineralised water.
The Applicant has found that these objects are achieved by providing a laundry machine with the features of claim 1.
Indeed, the Applicant found that the use of such a water absorbing element, by eliminating the use of a boiler, eliminates the need of using demineralised water, simplify the design and construction of the laundry machine, improve the reliability of the steam generator and lengthen the lifetime of the steam generator.
In addition, as shown below, in some advantageous embodiments of the present invention, the use of such a water absorbing element can eliminate or greatly reduce the need of water refilling in the steam generator.
Accordingly, in a first aspect the present invention relates to a laundry machine comprising a chamber for treating the laundry, a steam generator adapted to supply steam into the chamber so as to steam treating the laundry, wherein said steam generator comprises:

a water absorbing element, adapted to absorb water at a temperature lower than a temperature threshold T and to release steam at a temperature equal to or higher than this temperature threshold T, and
a heater adapted to heat the water absorbing element at a temperature at least equal to said temperature threshold T.

The water absorbing element is adapted to asorb water from ambient air (that is, to absorb water molecules naturally present in the air as air moisture). This advantageously enables to eliminate or greatly reduce the need of water refilling in the steam generator.
In an advantageous embodiment, in order to improve the efficiency of the steam generator (e.g. for guaranteeing the possibility of performing different steam generation cycles at close time distances), the steam generator is connected to a water source (adapted to provide said water absorbing element with water).
In an advantageous embodiment, the water source can be an external water supply line, located outside the laundry machine.
In another advantageous embodiment, the water source can be a water tank housed in the laundry machine.
Advantageously, the water absorbing element can operate with tap water and does not need to operate with demineralised water.
When the laundry machine is a drying machine or a washing-drying machine, it opportunely comprises a hot-air generator. In an advantageous embodiment, the hot-air generator comprises a heat exchanger and a hot-air generator heater. The heat exchanger and the hot-air generator heater are opportunely located one after the other along an air recirculation conduit, the two ends of which are connected to the chamber, advantageously on opposite sides of the chamber. The heat exchanger is opportunely adapted to cool the air in order to condense the surplus moisture in the airflow from the chamber, and the hot-air generator heater is opportunely adapted to heat the airflow from the heat exchanger back to the chamber.
In this embodiment, the laundry machine advantageously comprises a water collector adapted to collect the water condensed by the heat exchanger. The water source for the water absorbing element can advantageously be the water collector.
In a preferred embodiment, when the laundry machine is a drying machine, the chamber is a drum rotatably positioned inside a cabinet or housing of the machine and in which the laundry to be dried may be loaded, in order to be submitted to a drying and/or refreshing cycle.
In a different advantageous embodiment, when the laundry machine is a washing machine or a washing-drying machine, the chamber comprises a washing tub and a drum, rotatably contained in the tub, where the laundry may be loaded in order to be submitted to a washing cycle, a refreshing cycle, or, in case of a washing-drying machine, also a drying cycle. In this embodiment, the steam generator can be adapted either to supply steam into the tub, from which the steam is diffused into the drum, or to directly supply the steam into the drum.
In an advantageous embodiment, when the laundry machine is a washing machine or a washing-drying machine, the water absorbing element can be located in the bottom of the tub. In this way, the water source can be the bottom of the tub; in fact washing/rinsing liquid (i.e. water or water mixed with washing/rinsing agents) typically settles, at least during part of a washing cycle, on the bottom of the tub.
Preferably, the water absorbing element is located in the bottom of the tub at a level higher than a minimum liquid level in the bottom of the tub (that is the minimum level reached by the liquid present in the bottom of the tub, if any, after the end of washing/rinsing/discharge cycles). This position advantageously enables the water absorbing element to be wetted by the liquid present in the bottom of the tub during the washing/rinsing/discharge cycles (thereby enabling the water absorbing element to absorb water) and to be outside the liquid, above the minimum liquid level, at the end of the washing/rinsing/discharge cycles (thereby enabling the water absorbing element to release steam when positioned outside the liquid).
Opportunely, the bottom of the tub is fluidly connected to a water outlet circuit.
The water outlet circuit can opportunely comprise a draining pump and draining pipes, adapted for discharging liquid (i.e. water or water mixed with washing and/or rinsing products) from the tub after washing and rinsing cycles.
In an advantageous embodiment, the water outlet circuit comprises a water recirculation circuit, adapted to drain the liquid from the bottom of the tub and to re-convey it into another region, preferably a higher region, of the tub. In this embodiment, the water source for the water absorbing element can be the recirculation circuit. For example, the water absorbing element can be located within the water recirculation circuit or outside it, in fluid communication with it, so as to be wetted by water circulating in the recirculation circuit.
Opportunely, the laundry machine may comprise at least one further heater for generating hot air and/or hot water to be supplied into the chamber during drying or washing cycles. Preferably, the heater of the steam generator is different from said at least one further heater. This enables to heat the water absorbing element at a selected temperature, higher than said temperature threshold T, indipendently from the temperatures used for generating the hot air and the hot water in drying/washing cycles (that can be for example of about 80°C and 90°C, respectively). According to an advantageous variant, the heater of the steam generator can be the same heater used for generating the hot air or as the same heater used for generating the hot water.
In a second aspect the present invention relates to a method of laundry treatment in a laundry machine provided with a steam generator comprising a water absorbing element adapted to absorb water at a temperature lower than a temperature threshold T and to release steam at a temperature higher than said temperature threshold T, the method comprising:

making said water absorbing element absorb water at a temperature lower than said temperature threshold T;
heating said water absorbing element at a temperature at least equal to said temperature threshold T so as to generate steam;
conveying the generated steam into the laundry and steam treating the laundry.

The action of making said water absorbing element absorb water at a temperature lower than said temperature threshold T is performed by putting the water absorbing element in fluid communication with ambient air. This advantageously enables to eliminate or greatly reduce the need of water refilling in the steam generator, since the water absorbing element absorbs water directly from the air humidity.
According to an advantageous embodiment, in order to improve the efficiency of the steam generator (e.g. for guaranteeing the possibility of performing different steam generation cycles at close time distances), the action of making said water absorbing element absorb water at a temperature lower than said temperature threshold T is performed by supplying water to the water absorbing element from a water source.
In an advantageous embodiment, the water source can be an external water supply line, located outside the laundry machine. In another advantageous embodiment, the water source can be a water tank housed in the laundry machine.
When the laundry machine is a drying machine or a washing-drying machine, it opportunely comprises a hot-air generator. In an advantageous embodiment, the hot-air generator comprises a heat exchanger and a hot-air generator heater. In this embodiment, the laundry machine advantageously comprises a water collector adapted to collect the water condensed by the heat exchanger. The action of making said water absorbing element absorb water at a temperature lower than said temperature threshold T can advantageously be performed by supplying water to the water absorbing element from the water collector.
When the laundry machine is a washing machine or a washing-drying machine, it opportunely comprises a washing tub and a drum, rotatably contained in the tub, where the laundry may be loaded in order to be submitted to a washing cycle, a refreshing cycle, or, in case of a washing-drying machine, also a drying cycle. In this embodiment, the action of conveying the generated steam into the laundry can be performed by conveying the generated steam into the tub and letting the steam diffuse into the drum, or by directly conveying the generated steam into the drum.
In an advantageous embodiment, when the laundry machine is a washing machine or a washing-drying machine, the action of making said water absorbing element absorb water at a temperature lower than said temperature threshold T can be advantageously performed by supplying water to the water absorbing element from the bottom of the tub. The water absorbing element is advantageously wetted by the liquid present in the bottom of the tub during the washing/rinsing/discharge cycles.
When the laundry machine is a washing machine or a washing-drying machine it advantageously comprises a water outlet circuit comprising a draining pump and draining pipes, adapted for discharging a liquid from the tub after washing and rinsing cycles.
In an advantageous embodiment, the water outlet circuit comprises a water recirculation circuit, adapted to drain the liquid from the bottom of the tub and to re-convey it into another region, preferably a higher region, of the tub. In this embodiment, the action of making said water absorbing element absorb water at a temperature lower than said temperature threshold T is performed by supplying water to the water absorbing element from the recirculation circuit.
The present invention according to the first aspect and to the second aspect can have at least one of the following characteristics.
Preferably, when heated at said temperature higher than said temperature threshold T, the water absorbing element is adapted to release steam whose temperature is not higher than about 100-120°C. In fact, temperatures higher than 100-120°C could damage the laundry. In an advantageous embodiment said temperature threshold T can be, for example, at least equal to about 120°C (i.e. T≥120°C).
In an advantageous embodiment said temperature threshold T can be, for example, at least equal to about 180°C (i.e. T≥180°C).
In another advantageous embodiment said temperature threshold T can be, for example, at least equal to about 250°C (i.e. T≥250°C).
The water absorbing element can preferably be a water absorbing material in the form of spherical pellets, rods, or monoliths.
The water absorbing material can be selected from the group comprising: oxygen-containing compounds, including materials such as silica gel and zeolite; carbon-based compounds, including materials such as activated carbon and graphite; and polymer-based compounds.
In an advantageous embodiment the water absorbing material comprises around 500 g of zeolites; Applicant's tests have shown that, once water has been absorbed, this advantageous quantity of zeolites is able to release, when heated at the respective temperature threshold an amount of water (in the guise of steam) of about 175 g, which are enough for treating laundry in a drying cycle.
Features and advantages of the present invention will be more readily understood from the following detailed description of some preferred embodiments thereof, which is given below by way of non-limiting example with reference to the accompanying drawings, in which:

figure 1 schematically shows a laundry machine according to the invention;
figure 2 schematically shows a first embodiment wherein the laundry machine of figure 1 is a washing machine;
figure 3 schematically shows a first embodiment of the laundry machine of figure 2, wherein only some particulars of the laundry machine of figure 2 are shown;
figure 4 schematically shows a second embodiment of the laundry machine of figure 2, wherein only some particulars of the laundry machine of figure 2 are shown;
figure 5 schematically shows a third embodiment of the laundry machine of figure 2, wherein only some particulars of the laundry machine of figure 2 are shown;
figure 6 schematically shows a second embodiment wherein the laundry machine of figure 1 is a drying machine;
figure 7 schematically shows a first embodiment of the laundry machine of figure 6, wherein only some particulars of the laundry machine of figure 6 are shown;
figure 8 schematically shows a second embodiment of the laundry machine of figure 6, wherein only some particulars of the laundry machine of figure 6 are shown;
figure 9 schematically shows a third embodiment of the laundry machine of figure 6, wherein only some particulars of the laundry machine of figure 6 are shown.

Like elements are denoted by like reference signs throughout the figures.
Figure 1 shows a laundry machine 1 according to the invention, comprising a chamber 10 for treating the laundry and a steam generator 20 adapted to supply steam into the chamber 10 so as to steam treating the laundry.
The steam treatment can, for example, be performed to subject the cloths to a steam-refreshing cycle or to eliminate (or reduce) creasing of the cloths after a drying or spin-drying cycle.
The laundry machine 1 can be a washing machine, a drying machine or a washing-drying machine.
The laundry machine 1 can be a front-loading or a top-loading laundry machine.
The laundry machine 1 advantageously comprises an external casing 2.
In an advantageous embodiment, in whihc the laundry machine is a washing machine or a washing-drying machine, the chamber 10 is advantageously connected to the external casing 2 via a flexible bellows or gasket (not shown).
The steam generator 20 comprises a water absorbing element 21 adapted to absorb water at a temperature lower than a temperature threshold T (i.e. when the temperature of the water absorbing element is lower than the temperature threshold T) and to release steam at a temperature higher than this temperature threshold T (i.e. when the temperature of the water absorbing element is equal to or higher than the temperature threshold T), and a heater 22 adapted to heat the water absorbing element 21 at a temperature higher than or equal to said temperature threshold T.
The steam generator 20 is advantageously adapted to supply the steam generated into the chamber 10.
Advantageously, the steam generator 20 is in fluid communication with the chamber 10.
For example, the steam can be conveyed into the chamber 10 by means of at least one pipe 23 and, preferably, a suitable valve (not shown). The steam flow can be directed from the steam generator 20 into the chamber by means of a suitable fan (not shown) or by creating a suitable depression into the chamber 10.
The water absorbing element 21 can preferably be a water absorbing material in the form of spherical pellets, rods, or monoliths.
The water absorbing material can preferably be contained in a suitable container.
The water absorbing material advantageosuly has high abrasion resistance, high thermal stability and small pore diameters, which results in higher exposed surface area and hence high surface capacity for absorption.
The water absorbing material can preferably be selected from the group comprising:
oxygen-containing compounds, including materials such as silica gel (including alumina) and zeolite; carbon-based compounds, including materials such as activated carbon and graphite; and polymer-based compounds.
The heater 22 can, for example, comprise an electric resistor, or a source of microwaves, or an infrared light, ecc.
The heater 22 is thermally coupled with the water absorbing element 21 so as to heat the water absorbing material at a temperature equal to or higher than said temperature threshold T.
For example, when the absorbing material is zeolite, the temperature threshold T can be about 250°C; when the absorbing material is alumina, the temperature threshold T can be about 180°C; when the absorbing material is silica gel, the temperature threshold T can be about 120 - 180°C.
Advantageously, the water absorbing element used is such that when heated at said temperature higher than or equal to said temperature threshold T, it releases steam at a temperature not higher than about 100-120°C. In fact, temperatures higher than 100-120°C could damage the laundry. Figure 2 schematically shows an embodiment of the invention wherein the laundry machine 1 of figure 1 is a washing machine.
In this embodiment, the chamber 10 comprises a washing tub 11 and a drum 12, rotatably contained in the tub 11, where the laundry may be loaded in order to be submitted to a washing cycle, a steam treatment cycle, or, in case of a washing-drying machine, also a drying cycle. The drum 12 preferably is perforated (even if in the enclosed figures the holes obtained in the surface of the rotatable perforated drum 12 are not represented).
The steam generator 20 can be adapted either to supply steam into the tub 11, from which the steam is diffused into the drum 12, or to supply the steam directly into the drum 12.
In the embodiment of figure 2, the laundry machine 1 advantageously further comprises a water inlet circuit 3 adapted to feed water and washing/rinsing products (i.e. detergents, softeners, etc.) into the washing tub 11. The water inlet circuit 3 advantageously comprises a drawer 4, first piping 3a and a second pipe 3b.
The drawer 4, preferably removable, is adapted to be filled with washing and/or rinsing products, for example detersives, softener, bleaching substances, etc. The drawer 4 can comprise one or more compartments (exemplarily three in figure 2) for one or more washing/rinsing products from which a certain amount of these washing/rinsing products, depending on the washing program, is delivered to the washing tub 11. The first piping 3a are connectable to water delivery mains (not shown) present outside the washing machine 1 and are adapted to deliver prefereably fresh water to the drawer 4. First piping 3a are advantageously connectable to water delivery mains by means of one or more valves 3c (exemplarily three in figure 2, represented on the whole with reference number 3c) adapted to control the flow of water. The second pipe 3b fluidly connects the drawer 4 and the tub 11 and is adapted to deliver water and washing/rinsing products into the washing tub 11.
In the embodiment of figure 2, the laundry machine 1 advantageously also comprises a water outlet circuit 5.
Opportunely, the water outlet circuit 5 is fluidly connected to the bottom of the tub 11.
The water outlet circuit 5 advantageously comprises a drain pump 6, a first pipe 7 connecting the tub 11 to the drain pump 6 and an outlet pipe 8 ending outside the external casing 2. The water outlet circuit 5 is suited to drain the liquid, i.e. water or dirty water or water mixed with washing and/or rinsing products, from the tub 11 to the outside.
The water outlet circuit 5 preferably comprises also a filter 7a associated with the first pipe 7 and adapted for allowing the passage of washing liquid and for impeding the passage of bodies of fixed dimensions from the washing tub 11 to the drain pump 6. These bodies can be, for example, buttons, coins or other little objects contained in the pockets of trousers or other clothes and erroneously introduced into the laundry machine 1, lint, fluff, etc.
Optionally, the water outlet circuit 5 can be advantageously provided with a recirculation circuit 9 adapted to drain liquid from the bottom of the tub 3 and to re-convey it into another region, preferably a higher region, of the tub 11. The recirculation circuit 9 preferably comprises the drain pump 6 (or, in a different embodiment, a further dedicatdd pump) and a recirculation pipe 9a. The recirculation pipe 9a advantageously ends with an injection nozzle (not shown) in an upper region of the tub 11. In further preferred embodiments other injection nozzles in different locations along the tub 11 may be provided.
Advantageously, at the level of the bottom of the laundry washing machine 1, and preferably within the bottom of the tub 11, there is a heating element 13.
The heating element 13 preferably comprises an electric resistor suited to come into contact with the liquid present in the bottom of the tub 11 to heat said liquid. In further embodiments the heating element 13 may be a different element adapted to heat the liquid at the bottom of the tub, as for example a microwaves source, infra-red rays, etc.
A control unit (not shown) is connected to the various parts of the laundry machine 1 in order to control its operation.
In order to perform steam treatments, the control unit is advantageously configured to carry out the method of the invention.
Preferably, the control unit is configured to make the water absorbing element 21 absorb water at a temperature lower than said temperature threshold T; and, when a steam treatment is required, to heat the water absorbing element 21 at a temperature equal to or higher than said temperature threshold T so as to generate steam, and to convey the generated steam into the chamber 10 so as to subject the laundry to a steam treatment.
The water absorbing element 21 can absorb water within the laundry machine 1 of figure 2 according to different embodiments of the inventions.
Some of these different embodiments are exemplarily shown in figure 3-5 wherein, for the sake of clarity, only some particulars of the laundry machine 1 of figure 2 are shown.
In the embodiment shown in figure 3 the water absorbing element 21 is in fluid communication with ambient air and absorbs water from ambient air (that is, water molecules naturally present in the air as air moisture).
According to the embodiment shown in figure 4, the steam generator 20 is positioned in the bottom of the tub 11. In this way, the water absorbing element 21 can be wetted by the liquid present in the bottom of the tub during washing/rinsing/discharge cycles.
Preferably, the water absorbing element 21 is positioned in the bottom of the tub 11 at a level higher than a minimum liquid level in the bottom of the tub 11 (that is the minimum level reached by the liquid present in the bottom of the tub 11, if any, after the end of the washing/rinsing/discharge cycles). This position advantageously enables the water absorbing element 21 to be wetted by the water present in the bottom of the tub during the washing/rinsing/discharge cycles (thereby enabling the water absorbing material to absorb water) and to be outside the water, above the minimum water level, at the end of the washing/rinsing/discharge cycles (thereby enabling the water absorbing element to release steam when positioned outside the water).
In a variant (not shown) of the embodiment of figure 4, the heater 22 of the steam generator can be the same as (or part of) the heating element 13 positioned in the bottom of the tub 11 for heating the washing/rinsing liquid.
According to another embodiment, the water source for the water absorbing element 21 can be an external water supply line, located outside the laundry machine.
For example, figure 5 shows an embodiment wherein the steam generator 20 is in fluid communication with water delivery mains by means of a valve 3d.
According to another embodiment (not shown), the water source for the water absorbing element 21 can be a water tank housed in the laundry machine 1. The water tank can be, for example, manually refilled with tap water by a user.
According to an advantageous embodiment (not shown), the water absorbing element can be located within the water recirculation circuit 9 or outside it, in fluid communication with it, so as to be wetted by the water circulating in the recirculation circuit 9.
Figure 6 shows an embodiment of the invention wherein the laundry machine 1 of figure 1 is a drying machine.
In this embodiment, the chamber 10 advantageously is a drum rotatably positioned inside the external casing 2 and in which the laundry to be dried may be loaded, in order to be submitted to a drying and/or refreshing cycle.
In the embodiment of figure 6, the laundry machine 1 opportunely comprises a hot-air generator 30.
Preferably, the hot-air generator 30 is of the closed-circuit type, comprising an air recirculation conduit 31, the two ends of which are connected to the chamber 10, preferably on opposite sides of the chamber 10; a fan 32 (or other type of air circulating pump) located along recirculation circuit 31 to produce, inside recirculation circuit 31, an airflow which flows into the chamber 10 and over the laundry inside the chamber 10; a heat exchanger 33 (referred to also as a condenser) and a hot-air generator heater 34 (in the example shown it is an electrical resistor, but it may be for example also a heat pump system) located along the air recirculation conduit 31, downstream of the heat exchanger 33.
The heat exchanger 33 is opportunely adapted to cool the air in order to condense the surplus moisture in the airflow from the chamber 10, and the hot-air generator heater 34 is opportunely adapted to heat the airflow from the heat exchanger 33 back to the chamber 10.
Optionally, as shown in the embodiment shown in figure 6, the laundry machine 1 can advantageously also comprise a condense recirculation circuit 35 adapted to drain condensed water from the heat exchanger 33 and to convey it into a water collector 37. The recirculation circuit 35 preferably comprises a drain pump 36 and a recirculation pipe 35a.
A control unit (not shown) is connected to the various parts of the laundry machine 1 in order to ensure its operation.
In order to perform steam treatments, the control unit is advantageously configured to carry out the method of the invention.
Similarly to what disclosed above with reference to the embodiment of figure 2, the control unit is advantageously configured to make the water absorbing element 21 absorb water at a temperature lower than said temperature threshold T; and, when a steam treatment is required, to heat the water absorbing element 21 at a temperature equal to or higher than said temperature threshold T so as to generate steam, and to convey the generated steam into the chamber 10 so as to subject the laundry to a steam treatment.
The water absorbing element 21 can absorb water within the laundry machine 1 according to different embodiments of the invention.
Some of these different embodiments are exemplarily shown in figure 7-9 wherein, for the sake of clarity, only some particulars of the laundry machine 1 of figure 6 are shown. In a preferred embodiment shown in figure 7, wherein the laundry machine 1 comprises the condense recirculation circuit 35 and water collector 37, the water collector 37 is advantageously used as water source for the water absorbing element 21. The steam generator 20 advantageously is in fluid communication with the water collector 37 by means, for example, of a pipe 38 and a drain pump 39.
In another advantageous embodiment shown in figure 8, the water absorbing element 21 is in fluid communication with ambient air and absorbs water from ambient air. In this embodiment, even if shown in the figure, the presence of the condense recirculation circuit 35 and water collector 37 are optional.
According to another advantageous embodiment shown in figure 9, the water source for the water absorbing element 21 can be an external water supply line, located outside the laundry machine 1. In this embodiment the presence of the condense recirculation circuit 35 and water collector 37, even if shown in the enclosed figure, are optional. For example, figure 9 shows an embodiment wherein the steam generator 20 is in fluid communication with water delivery mains by means of a valve 3d.
According to another embodiment (not shown), the water source for the water absorbing element 21 can be a water tank housed in the laundry machine 1 that can be, for example, manually refilled with tap water by a user. Also in this embodiment, the presence of the condense recirculation circuit 35 and water collector 37 are optional.
The latter mentioned embodiments can, for example, be useful when the laundry machine 1 of figure 6 is unprovided with a condense recirculation circuit 35. For example, this may be the case when the laundry machine 1 of figure 6 has a hot-air generator of the open-circuit type instead of the closed-circuit type. In such a case, the hot-air generator 30 of the open-circuit type (not shown) will opportunely comprise an intake manifold connecting a wall (preferably the rear wall) of the chamber 10 to an air inlet; an air exhaust manifold connected at one end to a wall (preferably the front wall) of the chamber 10 and at the other end to an air exhaust outlet at the front of the casing 2; an electric heating element located along the intake manifold to heat the air before it is fed into the chamber 10; and a fan located along the exhaust manifold to draw air along the intake manifold, feed the air into the chamber 10 and expel the moist air through the exhaust manifold.
When the laundry machine 1 is a washing-drying machine, all embodiments, disclosed above with reference to a washing machine and to a drying machine, advantageously apply.
From the above description it will be clear that with respect to the known machine described above, the use of the water absorbing element 21 enables to eliminate the need of using demineralised water.
In addition, apart from the embodiments mentioned above wherein a water tank manually refillable is used for supplying water to the water absorbing element 21, the invention, in advantageous embodiments thereof, enables to eliminate the need of manual water refilling in the steam generator.
Furthermore, the embodiments of figures 3 and 8 enable to completely eliminate water refilling in the steam generator (when the embodiments are used alone) or to greatly reduce the need of water refilling (for example, when such embodiments are combined with other embodiments of the invention).

Claims

Laundry machine (1) comprising a chamber (10) for treating the laundry, and a steam generator (20) adapted to supply steam into the chamber (10) so as to steam treating the laundry,
wherein said steam generator (20) comprises:
- a water absorbing element (21), adapted to absorb water at a temperature lower than a temperature threshold T, and to release steam at a temperature equal to or higher than said temperature threshold T, and

- a heater (22) adapted to heat the water absorbing element at a temperature at least equal to said temperature threshold T,
characterized in that the water absorbing element (21) is adapted to absorb water from ambient air.
Laundry machine (1) according to claim 1, wherein the steam generator (20) is connected to a water source.
Laundry machine (1) according to claim 2, wherein the laundry machine is a drying machine or a washing-drying machine and comprises:
- a hot-air generator (30) comprising a heat exchanger (33) and a hot-air generator heater (34), and

- a water collector (37) adapted to collect water condensed by the heat exchanger (33),
said water source being said water collector (37).
Laundry machine (1) according to claims 1 or 2, wherein the laundry machine (1) is a washing machine or a washing-drying machine and said chamber (10) comprises a tub (11) and a drum (12), rotatably contained in the tub (11).
Laundry machine (1) according to claim 4, wherein the water absorbing element (21) is located in the bottom of said tub (11).
Laundry machine (1) according to claim 5, wherein said water absorbing element (21) is located in the bottom of said tub (11) at a level higher than a minimum liquid level reached by a liquid in the bottom of the tub (11), if any, after end of washing/rinsing/discharge cycles.
Laundry machine (1) according to claims 2 and 4, comprising a water outlet circuit (5) comprising:
- a draining pump (6),

- draining pipes (7, 8), adapted for discharging liquid from the tub (11) after washing and rinsing cycles, and

- a water recirculation circuit (9, 9a), adapted to drain the liquid from the bottom of the tub (11) and re-convey it into another region of the tub (11),
wherein
the water source is the recirculation circuit (9, 9a).
Laundry machine (1) according to any of claims 1 to 7, wherein the water absorbing element (21) comprises a water absorbing material selected from the group comprising:
oxygen-containing compounds, including silica gel and zeolite; carbon-based compounds, including activated carbon and graphite; and polymer-based compounds.
Method of laundry treatment in a laundry machine (1) provided with a steam generator (20) comprising a water absorbing element (21) adapted to absorb water at a temperature lower than a temperature threshold T and to release steam at a temperature equal to or higher than said temperature threshold T,
wherein the method comprises:
- making said water absorbing element (21) absorb water at a temperature lower than said temperature threshold T;

- heating said water absorbing element at a temperature at least equal to said temperature threshold T so as to generate steam;

- conveying the generated steam into the laundry and steam treating the laundry,
characterized in that
the action of making said water absorbing element (21) absorb water at a temperature lower than said temperature threshold T is performed by putting the water absorbing element in fluid communication with ambient air.
Method according to claim 9, wherein the action of making said water absorbing element (21) absorb water at a temperature lower than said temperature threshold T is performed by supplying water to the water absorbing element (21) from a water source.
Method according to claim 9 or 10, wherein the laundry machine is a drying machine or a washing-drying machine comprising:
- a hot-air generator (30), the hot-air generator (30) comprising a heat exchanger (33) and a hot-air generator heater (34), and

- a water collector (37) adapted to collect water condensed by the heat exchanger (33),
wherein the action of making said water absorbing element (21) absorb water at a temperature lower than said temperature threshold T is performed by supplying water to the water absorbing element (21) from the water collector (37) .
Method according to claim 9 or 10, wherein the laundry machine (1) is a washing machine or a washing-drying machine comprising a tub (11) and a drum (12) rotatably contained in the tub (11), and the action of making said water absorbing element (21) absorb water at a temperature lower than said temperature threshold T is performed by supplying water to the water absorbing element from the bottom of the tub (11).
Method according to claim 9 or 10, wherein the laundry machine (1) is a washing machine or a washing-drying machine comprising a tub, a drum rotatably contained in the tub, and a water outlet circuit (5) comprising:
- a draining pump (6),

- draining pipes (7, 8), adapted for discharging a liquid from the tub (11) after washing and rinsing cycles, and

- a water recirculation circuit (9, 9a), adapted to drain the liquid from the bottom of the tub (11) and re-convey it into another region of the tub (11),
wherein the action of making said water absorbing element (21) absorb water at a temperature lower than said temperature threshold T is performed by supplying water to the water absorbing element (21) from the recirculation circuit (9, 9a).