Patent Publication Number: US-9901238-B2

Title: Washing machine comprising a de-scaling apparatus

Description:
The present invention relates to washing appliances, particularly apparatuses for washing dishware. In more detail, the present invention regards dishwashing machines, or dishwashers, for both professional and domestic use, comprising a descaling apparatus adapted to remove limestone deposits and scales accumulations. 
     A generic dishwasher comprises a hydraulic circuit adapted to receive water from a water supply network and use it, usually together with detergent products and other products—generally referred to as dishwashing products in the following—, such as for example detergent and rinsing aid products for washing and/or rinsing dishware stored in a washing chamber provided in the dishwasher. 
     In the hydraulic system water from the water supply network may be pumped in predetermined amounts, e.g. determined by a selected washing cycle by a user, in a mixing chamber where water may be mixed with rinsing products and, therefrom, a resulting mix of water and rinsing products—referred to as rinsing liquid in the following—is pumped into a boiler to be heated and then into the spray arms positioned in the washing chamber of the dishwasher, where the rinsing liquid is sprayed by the spray arms over the dishware, rinsing it. 
     In the washing chamber the rinsing liquid (or plain water if no rinsing products are added) may be mixed with detergent (washing) products (and identified as washing liquid in the following), to this purpose the washing chamber is provided with one or more products compartments in which dishwashing products are stored and from which dishwashing products are ejected during the washing cycle of the dishwasher. 
     The hydraulic system typically comprises a boiler in which rinsing liquid or water from the water supply network (if no rinsing product is added) is heated up to a predetermined operating temperature (e.g. determined by the selected washing cycle selected), a plurality of pumps and valves for controlling flows of the water and/or the dishwashing products (both separately or mixed together) along pipes of the hydraulic system. 
     For example, the rinsing liquid being heated in the boiler may be directly pumped into one or more (rotating) spray arms positioned in the washing chamber of the dishwasher to rinse the dishware stored therein during rinsing phase(s) of the selected washing cycle of the dishwasher. 
     A bottom portion of the washing chamber may comprise, or be fluidly connected to, a drain tank, or sump assembly, where the washing or rinsing liquid is collected and may be discharged through a drain portion of the hydraulic circuit into a sewer network, during the selected washing cycle and particularly at the end thereof. 
     The hydraulic system may also comprise a recirculating circuit designed to filter, heat and pump the washing liquid collected in the drain tank during the washing cycle back to the spray arms (or to other spray arms provided in the washing chamber as well). In this way, the washing liquid collected in the drain tank is re-used reducing the total amount of water needed for performing the washing cycle. 
     Unfortunately, during use of the dishwasher, insoluble solid limestone (i.e., calcium carbonate CaCO 3 ) may form (i.e., deposit) within the hydraulic system, other parts of the dishwasher exposed to the washing and/or rinsing liquids (e.g., the washing chamber and the boiler) and also on the dishware within the washing chamber due to calcium ions diluted in the water. Limestone deposition, or encrustation, is exacerbated by the increased temperatures of the washing/rinsing liquid. Indeed, the operating temperatures (e.g., up to 90° C.) of the washing/rinsing liquid reduce the level of carbon dioxide dissolved in the water from the water supply network, which results in calcium ions precipitation with a subsequent limestone deposition. 
     The limestone deposition on the heating elements of the dishwasher has serious detrimental effects on the lifetime thereof and on their efficiency in terms of absorbed power. For example, limestone deposition on heating resistors (immersed in washing/rinsing liquid during the operation of the dishwasher) used to heat the rinsing water in the boiler of the dishwasher or used to heat washing/rinsing liquid collected in the sump assembly (when the recirculating circuit is provided) reduces the dishwasher performances. Indeed, the limestone deposition on the heating elements reduces a thermal exchange capability thereof. Such reduction in the thermal exchange capability causes an increase in the power consumption and time needed for heating the washing/rinsing liquid to a desired operating temperature and causes an acceleration of wearing out of the heating elements due to an increase of the surface temperature thereof during operation. 
     Moreover, due to the steep temperature changes (also referred to as thermal shocks), caused by the use of fresh water from the water supply network during a washing cycle, the limestone tends to detach from its deposition site (e.g., from a surface of the heating resistors) as scales. Such limestone scales, or simply scales, may enter into circulation throughout the hydraulic system and obstruct the spray nozzles of the spray arms. Furthermore, the limestone deposition and/or scales accumulation may reduce the cross sections of the pipes, causing a lower flow rate of the washing/rinsing liquid with respect to a flow rate needed by the dishwasher for proper operation. Finally, the pumps of the hydraulic system experiencing limestone deposition and/or scales accumulation on components thereof may increase the power absorption for overcoming the higher weight and friction up to a clogging of the pump, thus sensibly reducing their expected lifetime. 
     In the art, several of systems and procedures have been developed for reducing the limestone deposition and/or scales accumulation, which are referred to as descaler or delime systems and as descaling or delime procedures, respectively, in the following. 
     A number of descaler systems and/or descaling procedures have been provided for preliminary treating water in order to lower its hardness (i.e., a water parameter proportional to calcium ions concentration diluted in water). For example, systems implementing water softeners, reverse osmosis, nanofiltratrion and chemical treatments have been proposed in the art to combat limestone deposition and/or scales accumulation. However, the Applicant has perceived that such systems are highly expensive to be implemented and require a regular maintenance in order to operate properly. 
     Alternatively, in order to reduce and/or remove limestone deposits and/or scales accumulation it is possible to periodically execute a general maintenance of the machine by manually cleaning the individual portions of the hydraulic system (water lines, spray arms, boiler, etc.) with chemical treating agents, typically acid solutions. However, such maintenance requires a qualified technician to be carried out and requires an at least partial disassembly of the dishwasher (e.g., for treating the boiler and the boiler heating resistor). 
     The chemical treating agents are usually stored in encumbering tanks with a large capacity (e.g. 5 L or even more), which are (externally) connected (by a qualified technician) to a dedicated portion of the hydraulic system for performing a descaling procedure. The European Patent EP 2289385 from the same Applicant discloses an example of such a professional dishwasher. 
     The International Patent Application No. WO 2011/094852 discloses a dishwasher comprising a softener based on a capacitive-deionization (CDI) cell, in which the hardness ions are extracted, and disposed, still intact, in concentrated form. The softener is combined with a chelate to inhibit precipitation, in the appliance, from the concentrated effluent. The chelate being citric acid, the acidity is effective to keep the hardness ions in solution. The purify and regenerate modes of operation of the softener can be timed to coincide with the washing and rinsing cycles of the appliance, whereby the presence of the softener does not affect the speed and performance of the appliance. The Applicant has found that such a dishwasher has high power and water consumption for performing the softening of washing water every time fresh water is introduced in the hydraulic system and for often descaling the softener in order to have it operate with a substantially constant efficiency. 
     The Applicant has tackled the problem of devising a satisfactory solution able to provide a dishwasher implementing a simple system adapted to remove limestone deposition and/or scales accumulation, which can be operated by a non-specialized user without any particular technical training and/or knowledge. 
     The Applicant has found that by implementing a simple additional branch in the hydraulic system and by providing cartridge elements for storing treating agents to be used in the additional hydraulic branch, it is possible to properly prevent and remove limestone depositions without the need to disassemble the dishwasher and/or the intervention of a qualified technician. 
     One aspect of the present invention proposes a washing appliance for washing items. A washing appliance for washing items is proposed. The washing appliance has a hydraulic circuit comprising at least one tank adapted to store a predetermined amount of liquid, at least one heating element provided at least partly inside said at least one tank adapted to heat said predetermined amount of liquid to at least one predetermined temperature, a water inlet adapted to receive water from a water supply network, and a descaling apparatus. The descaling apparatus comprises a descaler chamber having a housing portion adapted to house a descaler product container containing a descaling agent and a mixing portion adapted to contain a mix of water and a predetermined amount of the descaling agent, the housing portion being fluidly connected to the mixing portion of the descaler chamber and an inlet pipe fluidly connecting the water inlet to the descaler chamber, the inlet pipe being adapted to provide water into the descaler chamber. In the solution according to an embodiment of the present invention, the descaling apparatus further comprises an outlet pipe fluidly connecting the mixing portion and the at least one tank, the outlet pipe being adapted to drain the mix of water and predetermined amount of descaling agent from the mixing portion and provide it to the at least one tank and a spraying element provided in the mixing portion of the descaler chamber and fluidly connected to the inlet pipe, the spraying element being adapted to spray water towards the housing portion. 
     Preferred features of the present invention are set in the dependent claims. 
     In an advantageous embodiment of the invention, the descaling apparatus further comprises a valve element provided in the inlet pipe and adapted to selectively allow a flow of water from the water inlet towards the spraying element. 
     In an advantageous embodiment of the invention, the housing portion of the descaler chamber comprises a support element protruding from an inner wall of the housing portion transversally therefrom, the support element being adapted to support the descaling product container. 
     In an advantageous embodiment of the invention, the housing portion of the descaler chamber is fluidly connected to the mixing portion of the descaler chamber by means of an aperture therebetween, said aperture being delimited by the support element. 
     In an advantageous embodiment of the invention, the housing portion of the descaler chamber further comprises a further aperture opposite to the aperture, said further aperture having a size and shape adapted to allow the insertion of the descaling product container into the housing portion. 
     In an advantageous embodiment of the invention, the washing appliance further comprises a washing chamber adapted to store wares to be treated and the further aperture is exposed on a bottom wall of the washing chamber. 
     In an advantageous embodiment of the invention, the descaling apparatus further comprises a lid adapted to close the further aperture of the housing portion of the descaler chamber. 
     In an advantageous embodiment of the invention, the washing appliance further comprises a casing and the further aperture is exposed on a panel of the casing. 
     In an advantageous embodiment of the invention, the mixing portion further comprises a funnel-shaped manifold fluidly connected to the outlet pipe. 
     In an advantageous embodiment of the invention, the support element comprises a hollow punching element is provided, the hollow punching element protruding transversally from a free periphery of the support element towards the top aperture. The hollow punching element is adapted to at least partially cut a descaler cap of the descaler product container. 
     A different aspect of the present invention proposes a descaling product container for the use in the washing appliance. The descaling product container comprises a container body adapted to contain a predetermined amount of a descaling agent, a container neck, a container aperture delimited by the container neck adapted to allowing access to the interior of the container body, and a container cap adapted to seal the container aperture. The container cap is made of a water-soluble material, or of a water-resistant material, and the descaling product container is adapted to be fitted in the housing portion of the descaler chamber. 
     A different aspect of the present invention proposes a method for operating the washing appliance. The method comprises the following steps. Providing a descaling agent in the descaler chamber. Allowing water from a water inlet into the inlet pipe of the descaling apparatus. Spraying water from the nozzle into the descaler chamber. Mixing together water and the descaling agent in the mixing portion of the descaler chamber in order to obtain a mix of water and of the descaling agent. Transferring the mix of water and of the descaling agent from the mixing portion of the descaler chamber into the at least one tank element through the outlet pipe. Heating the mix of water and of the descaling agent up to a predetermined temperature. Holding the mix of water and of the descaling agent in the at least one tank element for a predetermined reaction time in order to react with limestone deposition and/or scales in the at least one tank element. Discharging the mix of water and of the descaling agent through a drain portion of the hydraulic circuit of the washing appliance. 
     In an advantageous embodiment of the invention, the step of providing a descaling agent in the descaler chamber comprises fitting the descaling product container in the housing portion of the descaler chamber. Moreover, the step of spraying water from the nozzle in the descaler chamber comprises dissolving the container cap of the descaling product container in order to allow the descaling agent falling by gravity into the mixing portion of the descaler chamber together with the water sprayed by the nozzle. Alternatively, the step of providing a descaling agent in the descaler chamber comprises fitting the descaling product container in the housing portion of the descaler chamber, and at least partly punching the container cap. 
     In an advantageous embodiment of the invention, the step of providing a descaling agent in the descaler chamber comprises providing the descaling agent unpackaged in the descaler chamber. 
     In an advantageous embodiment of the invention, the at least one tank comprises a first tank element and a second tank element fluidly connected to each other. Moreover, the step of transferring the mix of water and of the descaling agent from the mixing portion of the descaler chamber into the at least one tank element through the outlet pipe comprises transferring the descaling liquid into the first tank element and providing the mix of water and of the descaling agent in the second tank element. The step of heating the mix of water and of the descaling agent up to a predetermined temperature comprises heating the mix of water and of the descaling agent up to a first predetermined temperature and heating the mix of water and of the descaling agent up to a second predetermined temperature. Furthermore, the step of holding the mix of water and of the descaling agent in the at least one tank element for a predetermined reaction time comprises holding the mix of water and of the descaling agent in the first tank element for a first predetermined reaction time and holding the mix of water and of the descaling agent in the second tank element for a second predetermined reaction time. 
    
    
     
       These and others features and advantages of the solution according to the present invention will be better understood by reading the following detailed description of some embodiments thereof, provided merely by way of non-limitative examples, to be read in conjunction with the attached drawings, wherein: 
         FIG. 1  is a schematic cross-sectional side view of a dishwasher according to an embodiment of the present invention, in which a hydraulic system thereof is outlined; 
         FIG. 2  is a schematic cross-sectional view of descaler chamber according to an embodiment of the present invention; 
         FIG. 3  is a schematic cross-sectional view of a dishwasher wherein a descaler container is being inserted in the descaler chamber according to an embodiment of the present invention; 
         FIG. 4  is a schematic cross-sectional view of a descaler chamber with a descaler container inserted thereinto according to an embodiment of the present invention; 
         FIG. 5  is a schematic cross-sectional view of a descaler chamber with a descaler container during a mixing of water and descaling agent; 
         FIGS. 6A-6B  are a schematic flow diagram of a descaling procedure according to an embodiment of the present invention; 
         FIGS. 7-9  are schematic cross-sectional views of a descaler chamber and of a descaler container according to an alternative embodiment of the present invention, and 
         FIG. 10  is a schematic partial cross-sectional view of an alternative dishwasher wherein a descaler container is being inserted into an alternative descaler chamber, according to an embodiment of the present invention. 
     
    
    
     With reference to the drawings,  FIG. 1  is a schematic cross-sectional view of a dishwasher  100  according to an embodiment of the present invention, in which a hydraulic system  102  thereof is schematically outlined. The dishwasher  100  comprises a casing  105 , typically parallelepiped-shaped, and preferably made of metal (e.g., stainless steel) and possibly covered by aesthetic panels (not shown). The casing  105  substantially encloses all the other components comprised in the dishwasher  100 . A washing chamber  110 , preferably substantially parallelepiped-shaped, is provided inside the casing  105  and is adapted to store dishware (not shown) to be washed. Preferably, one or more dishware racks (not shown) may be slidably provided in the washing chamber  110  in order to easily and efficiently store the dishware therein. For example, the dishware racks are adapted to rest on, and slide over a couple of rails (not shown) provided on opposite sidewalls of the washing chamber  100 . 
     In a bottom portion of the washing chamber  110  a drain tank, or sump assembly  112 , is provided. The water and/or water mixed with detergent products and/or rinsing products (such as for example cleaning, sanitizing, and/or sparkling aid products), generally referred to as washing or rinsing liquid in the following, respectively, is collected in the sump assembly  112  and may be discharged through a drain portion (not shown) of the hydraulic system  102  of the dishwasher  100  into a sewer network (not shown). 
     The washing chamber  110  is accessible by a user through a loading/unloading opening  115  provided in a front side of the dishwasher  100  allowing the user to load/unload dishware into/from the washing chamber  110 . A door  120  is provided in order to close the loading/unloading opening  115  in a watertight manner. For example, the door  120  and/or the loading/unloading opening  115  are provided with a sealing gasket, not shown, along respective rims thereof that mutually face each other when the door  120  closes the loading/unloading opening  115 . 
     One or more spray arms are provided inside the washing chamber  105  for washing the dishware during the operation of the dishwasher  100 . In the example of  FIG. 1 , four spray arms  125   a - d  are provided, two spray arms  125   a  and  125   b  hang from an upper wall  110   a  of the washing chamber  110 , preferably rotatably connected to a support projecting from the upper wall towards the center of the washing chamber  110 . The other two spray arms  125   c  and  125   d  are preferably rotatably connected to a common, or alternatively two respective, bearing arm(s) (not shown) projecting from a backwall  110   b  in close proximity to a bottom wall  110   c  of the washing chamber  110 . Preferably, the spray arms  125   c  and  125   d  are disposed in such a way to be parallel to the spray arms  125   a  and  125   b  and facing towards the center of the washing chamber  110 . 
     The spray arm  125   a  (provided at the upper wall  110   a ) and the spray arm  125   c  (provided at the bottom wall  110   c ), also referred to as rinsing spray arms  125   a  and  125   c  in the following, are fluidly connected to a rinse pipe  130  in which a boiler pump  135  pumps the rinsing liquid, sucked from a boiler  140  positioned upstream the boiler pump  135  and to which the latter is fluidly connected. 
     The boiler  140  is substantially a watertight tank, or reservoir, comprising a heating element, such as a heating resistor  142 , which is selectively energized during the operation of the dishwasher  100  in order to heat the rinsing liquid stored in the boiler  140  up to a predetermined temperature (e.g., defined by a selected washing cycle as known), before the rinsing liquid is pumped towards the spray arms  125   a  and  125   c  and therefrom into the washing chamber  110  for rinsing the dishware. 
     The rinsing liquid flows into the boiler  140  from a mixing chamber  145  to which is fluidly connected by a mixing pipe  150 . Preferably, the mixing chamber  145  is a watertight tank located in an upper position with respect to the boiler  140 . In this way, the rinsing liquid in the mixing chamber  145  may reach the boiler  140  simply by gravity (i.e., without the need of a pump or similar device). 
     Water is introduced into the mixing chamber  145  through a main pipe  155  fluidly connected to the water supply network (not shown) through a water inlet  157 . The amount of water introduced into the mixing chamber  145  is controlled by means of a main valve  160  (e.g., a solenoid valve). 
     In other embodiments according to the present invention, the mixing chamber  145  and the mixing pipe  150  may be omitted, with the main pipe  155 , which is directly connected to the boiler  140 , and with the mix between water and rinsing products that is performed directly in the boiler  140 . 
     The spray arm  125   b  (provided at the upper wall  110   a ) and the spray arm  125   d  (provided at the bottom wall  110   b ), referred to also as recirculating (or washing) spray arms  125   b  and  125   d  in the following, are fluidly connected to a recirculating pipe  165  in which a recirculating pump  170  pumps washing liquid, sucked from the sump assembly  112  positioned upstream the recirculating pump  170 , to which the latter is fluidly connected. In this way, a recirculating circuit that allows consuming reduced amounts of water is implemented. Advantageously, in the sump assembly  112  a heating element, such as another heating resistor  175 , is provided in order to heat the washing liquid or the rinsing liquid (if washing products are not mixed with the rinsing liquid in the washing chamber  110 ) collected in the sump assembly  112  up to the predetermined operating temperature (or to an alternative operating temperature). Preferably, the sump assembly  112  is further provided with a filter arrangement (not shown) adapted to block food scraps and other foreign matter from being sucked by the recirculating pump  170 . 
     The operation of the whole dishwasher  100  is managed by a (electronic) control unit  180  according to washing cycles selected by a user interacting with a control panel  185  of the dishwasher  100 . The control unit  180  is configured to operate the main valve  160 , the pumps  135  and  170  and the heaters  142  and  175 , as well as any other electrically-operable component provided in the dishwasher  100 —to which the control unit  180  is electrically connected by means of suitable wiring and, possibly, circuitry, not shown—according to predetermined instructions related to washing cycles selectable by the user, generally stored in a memory device comprised in the control unit  180 . 
     Advantageously, the control unit  180  is positioned inside the dishwasher  100  in a location isolated from water and moisture in order to be not damaged by them. In the example of  FIG. 1 , the control unit  180  and the control panel  185  are located in a top portion of the casing  105  of the dishwasher  100 , even though the control unit  180  and the control panel  185  may be placed in other positions (also spaced apart from each other), such as for example embedded in the door  120 . 
     In an embodiment according to the present invention, the dishwasher  100  further comprises a descaling apparatus  190 . The descaling apparatus  190  is now described by making joint reference to  FIGS. 1-5 . 
     The descaling apparatus  190  according to an embodiment of the present invention is designed to house a suitable descaling product unit or cartridge, such as for example a descaler product container, or simply descaler container  305  (as shown in  FIGS. 3-5 , and describe in detail in the following), to mix a descaling agent  310  contained in the descaler container  305  with water, thereby obtaining a descaling liquid, and to inject such descaling liquid into the hydraulic system  102  of the dishwasher  100  in order to combat limestone deposition and scales. 
     The descaling apparatus  190  comprises a descaler chamber  192  closed by a lid  193 , an inlet pipe  194  that fluidly connects the main pipe  155  to the descaler chamber  192  passing through a descaler valve  196  (e.g., a solenoid valve) that selectively blocks water incoming therefrom, and an outlet pipe  198  that fluidly connects the descaler chamber  192  with the boiler  140 . 
     The descaler chamber  192 —as can be best seen in  FIG. 2 , which is a schematic cross-sectional view of the descaler chamber  192  according to an embodiment of the present invention—preferably comprises a (top) housing portion  205  adapted to house the descaler container  305 . For example, the housing portion  205  has substantially a shape adapted to house the descaler container  305  (e.g., cylindrical even though prism-shaped alternative housing portions are not excluded, for housing correspondingly prism-shaped containers). 
     Preferably, the housing portion  205  comprises a top aperture  210  that, in the example at issue, opens on the washing chamber  110  in a portion of the bottom wall  110   c  thereof, e.g. next to the sump assembly  112 . The top aperture  210  is preferably provided close to the loading/unloading opening  115  of the washing chamber  110  in order to be easily reachable by a user (as described in detail later on). Preferably, the top aperture  210  may be selectively sealed by means of the, preferably removable, lid  193  that is adapted to isolate the descaler chamber  192  from the washing chamber  110  (when in closed position), preferably in a watertight manner. Preferably, on a rim  212  of the housing portion  205  that delimits the top aperture  210  engage elements (not visible in the figures) are provided, such as for example a threading or bayonet mounting receptacles (even though other types of engaging elements are not excluded). Such engage elements are adapted to engage with corresponding engage elements (not visible in the figures) provided in a engaging recess  193   a  of the lid  193 , when the lid  193  is coupled to the rim  212  of the housing portion  205  in order to close the top aperture  210 . 
     In alternative embodiments of the present invention (not shown in the figures), an alternative lid is hinged to the rim delimiting the top aperture of the housing portion of the descaler chamber. 
     The housing portion  205  is adapted to receive the descaler container  305  (as described in the following). At a lower end of the housing portion  205  (opposite to the top aperture  210 ), a support element  215  is provided. The support element  215  protrudes from an inner wall  220  (preferably transversal thereto) of the housing portion  205  and is adapted to support the descaler container  305  once the latter is inserted into the housing portion  205  (as described in the following). 
     The descaler chamber  192  further comprises a mixing portion  225  beneath the housing portion  205  (preferably formed integral therewith) that is fluidly connected to the mixing portion  225  by means of an aperture  217  delimited by the support element  215 . The mixing portion  225  is substantially a tank adapted to contain the descaling agent  310  and a predetermined amount of water (e.g., sufficient for dissolving a descaler powder in the container  305 , as described later). A nozzle  230  protrudes from a bottom wall  225   a  of the mixing portion  225 , preferably in a central portion thereof, and more preferably aligned with a symmetry axis of the housing portion  205 . The spray nozzle  230  is in fluid communication with the inlet pipe  194  of the descaling apparatus  190 . 
     The outlet pipe  198  fluidly connects the mixing portion  225  with the boiler  140 , (even if an indirect connection is possible, e.g. by fluidly connecting the outlet pipe with the mixing pipe  150 ). Preferably, the outlet pipe  198  is connected to the mixing portion  225  at the bottom wall  225   a  thereof. 
     As can be best appreciated in  FIGS. 3-4 , which are schematic cross-sectional views of the dishwasher  100  wherein the descaler container  305  is being inserted into the descaler chamber  192  according to an embodiment of the present invention, the descaler container  305  can be easily inserted into the descaler chamber  192  through the top aperture  210  of the housing portion  205  by a user accessing the washing chamber  110  through the loading/unloading opening  115 . 
     Preferably, the descaler container  305  is a vessel-like element adapted to contain a predetermined amount of the descaling agent  310 . Advantageously, the descaler container  305  may be sized for containing an amount of the descaling agent  310  needed to perform a single descaling treatment for removing limestone deposit and scales from the hydraulic system  102  of the dishwasher  100 . The descaling agent  310  may be in any form adapted for the use in the hydraulic circuit of the dishwasher  100 . For example, the descaling agent  310  may be provided in powder form, beads form, liquid form and/or gel form. 
     The descaler container  305  comprises a container body  315 , for example substantially shaped as a hollow cylinder. At one of its ends, the container body  315  has a shoulder portion  320 , substantially transversal to sidewalls  315   a  of the container body. A container neck  325  that delimits a container aperture  330  protrudes substantially transversally from the shoulder portion  320  (preferably parallel to the sidewalls  315   a ). Preferably, the shoulder portion  320  of the descaler container  305  may be formed inclined or curved in such a way to ensure a complete outflow of the descaling agent  310  from the descaler container  305  when the latter is inserted into the descaler chamber  192 . The container neck  325  and the container aperture  330  preferably have a diameter smaller than a diameter of the container body  315 . As can be best viewed in  FIG. 4 , the container neck  325  is preferably adapted to rest on the support element  215 , with the container aperture  330  (and the container cap  325  closing it) substantially aligned with aperture  217  delimited by the support element  215 . 
     Preferably, although not limitatively, the container body  315  is a one-piece element, i.e. the container shoulder  320  and the container neck  325  are formed integral with the rest of the container body  315 . The container body  315  is made of a material adapted to store the descaling agent  310  without experiencing leakages, such as for example a plastic polymer (e.g., polyethylene or polystyrene). In an embodiment of the invention, the descaler container  305  is adapted to be re-usable. 
     The container aperture  330  is sealed by a container cap  335  adapted to seal the descaling agent  310  in such a way to prevent any possibility of direct contact between the descaling agent  310  inside the container body  315  and the user handling the descaler container  305 . Preferably, although not limitatively, the container cap  335  may be provided in the form of a film of a suitable material adapted to be opened by a jet of water (as described in the following). For example, the container cap  335  may be formed of a water-soluble material (e.g., comprising wax). 
     The descaler container  305  may be safely and easily inserted (i.e., without the need of any particular training) in the housing portion  205  of the descaler chamber  192  by the user through the loading/unloading opening  115 . As shown in  FIG. 3 , the descaler container  305  is inserted into the housing portion  205 , through the top aperture  210  thereof, with the container cap  335  facing downwards (i.e., towards the support element  215  of the housing portion  205 ), down until the neck  325  reaches the support element  215  (and rests thereon). 
     Preferably, the lid  193 , once it closes the top aperture  210 , seals in a watertight manner the descaler chamber  192  with respect to the washing chamber  110  thereabove. 
     Therefore, the descaler container  305  is housed in the housing portion  205 , with the container aperture  330 , closed by the container cap  335 , facing towards the mixing portion  225  of the descaler chamber  192 . Preferably, the container aperture  330  is axially aligned with the nozzle  230  protruding from the bottom wall  225   a  of the mixing portion  225  of the descaler chamber  192 , to be hit by a spray from the nozzle  230  (as shown in  FIG. 5  and described in the following). 
     Once the descaler container  305  is housed in the housing portion  205  of the descaler chamber  192 , a descaling procedure  600 —of which  FIG. 6A-6B  is a schematic flow diagram according to an embodiment of the present invention—may be started. 
     Initially, a user places (phase  605 ) the descaler container  305  inside the housing portion  205  of the descaler chamber  192  and couples (phase  610 ) the lid  193  with the latter in order to seal the top aperture  210  (as discussed above). 
     Then, an automated portion of the descaling procedure  600  performed by the dishwasher  100  (e.g., determined by instructions stored in the control unit  180 ) may be preferably actuated (phase  615 ) by the user, for example by selecting a corresponding descaling command through the control panel  185  of the dishwasher  100 . In alternative embodiments of the present invention, the automated portion of the descaling procedure may be automatically activated by detection (by means of a suitable detection element provided in the dishwasher) of the insertion of the descaler container  305  in the descaler chamber  192  (after the closure of the door  120 ). 
     The automated portion of the descaling procedure comprises a complete emptying of the boiler  140  and of the sump assembly  112  (phase  620 ). Afterwards, the descaler valve  196  opens (phase  625 ), e.g., upon an electrical command provided by the control unit  180 , allowing water from the water supply network into the inlet pipe  194  of the descaling apparatus  190 . The water from the inlet pipe  194  is introduced into the nozzle  230 , by which it is sprayed (phase  630 ) towards the descaler container  305 . The water sprayed from the nozzle  230  advantageously collides with the container cap  335  dissolving (since the container cap  335  is made of water-soluble material) and/or breaking (thanks to the kinetic energy associated with the spraying) the container cap  335  (as shown in  FIG. 5 ). 
     Once the container cap  335  is removed by the sprayed water as just described, the descaling agent  310  falls by gravity into the mixing portion  225  of the descaler chamber  192  together with the water sprayed by the nozzle  230 . Preferably, the jet of water sprayed by the nozzle  230  may be designed to reach a bottom portion of the descaler container  305  opposite to the container aperture  330 . In this way, it is possible to completely empty the descaler container  305 , i.e. all the descaling agent  310  stored in the descaler container  305  falls into the mixing portion  225  beneath the support element  215 . 
     Water and the descaling agent  310  mix together (phase  635 ) in the mixing portion  225  (e.g., the descaling agent  310  dissolves in water) resulting in a liquid mixture referred to as descaling liquid in the following. 
     The descaling liquid outflows from the mixing portion  225  of the descaler chamber  192  through the outlet pipe  198  and is introduced (phase  640 ) into the boiler  140 . Preferably the valve  196  is maintained open until the liquid level inside the boiler  140  reaches a maximum liquid level allowed. For example, the descaling liquid may flow into the boiler  140  simply by gravity, provided that the descaler chamber  192  is arranged in the dishwasher  100  in a higher position than the position of the boiler  140 . Alternatively, a pump (not shown) may be provided in line with the outlet pipe  198  adapted to suck the descaling liquid from the descaler chamber  192  and pump it into the boiler  140 . 
     The descaling liquid in the boiler  140  is heated up (phase  645 ) by the heating resistor  142  to a predetermined operating temperature, such as for example comprised in range spanning from 70° C. to 80° C. The descaling liquid remains (phase  650 ) in the boiler  140  for a predetermined first reaction time (defined by the descaling procedure or manually input by the user through the control panel  185 ) in order to react with limestone deposits and/or scales, removing them from the walls of the boiler  140  and/or from the heating resistor  142  (by dissolving such limestone deposits and/or scales). In this way, it is possible to easily remove limestone deposit and/or scales from the boiler  140  and from its heating resistor  142  which are usually more seriously affected by limestone deposits and scales formation. 
     In an embodiment of the present invention, once the first reaction time has elapsed, the boiler pump  135  is operated (e.g., by the control unit  180 ) in order to suck the descaling liquid out from the boiler  140  into the rinse pipe  130  and then the descaling liquid is sprayed by the rinsing spray arms  125   a  and  125   c  into the washing chamber  110  (phase  655 )—thereby reacting with, and removing, the limestone deposits and/or scales in the boiler pump  135 , in the rinse pipe  130  and on the rinsing spray arms  125   a  and  125   c . In the washing chamber  110  the descaling liquid removes the limestone deposits and/or scales possibly formed/accumulated on the walls of the washing chamber  110 , and is collected in the sump assembly  112 . 
     Preferably, the descaling liquid inside the sump assembly  112  is heated up (phase  660 ) by the heating resistor  175  to the predetermined operating temperature (e.g., comprised in the range spanning from 70° C. to 80° C., even though different temperatures adapted to peculiar descaling agents are not excluded) and is held (phase  662 ) inside the sump assembly  112  for a predetermined second reaction time (again, defined by the descaling procedure or by the user through the control panel  185 ) during which the descaling liquid reacts with, and removes (dissolves), the limestone deposits and/or scales possibly formed/accumulated in the sump assembly  112  and/or on the heating resistor  175 . 
     Afterwards, the descaling liquid with dissolved limestone deposits and/or scales may be discharged (phase  665 ) through the drain portion of the hydraulic circuit of the dishwasher  100 . 
     In one embodiment of the present invention, the discharging of the descaling liquid is delayed and the recirculating pump  170  is operated (e.g., by the control unit  180 ) to suck the descaling liquid out from the sump assembly  112  into the recirculating pipe  165  and then the descaling liquid is sprayed (phase  670 ) by the recirculating spray arms  125   b  and  125   d  into the washing chamber  110 —thereby reacting with, and removing, the limestone deposits and/or scales in the recirculating pump  170 , in the recirculating pipe  165  and on the recirculating spray arms  125   b  and  125   d . This phase may be reiterated (phase  675 ) a predetermined number of times (again, defined by the descaling procedure or by the user through the control panel  185 ) during the automated portion of the descaling procedure  600 , e.g. in order to ensure a complete removal of limestone deposits and/or scales from the washing chamber  110 , the sump assembly  112 , the heating resistor  175 , the recirculating pump  170 , the recirculating pipe  165  and the recirculating spray arms  125   b  and  125   d . Finally, the descaling liquid together with the removed limestone deposits and/or scales are discharged (phase  665 ) through the drain portion (not shown) of the hydraulic circuit of the dishwasher  100  (ending the automated portion of the descaling procedure). 
     Thanks to the descaler apparatus  190  and the descaling procedure  600  just described, it is possible for any untrained user to easily remove limestone deposits and/or scales from substantially the whole hydraulic circuit of the dishwasher  100 . Moreover, thanks to the descaler container  305  according to embodiments of the present invention it is possible for any untrained user to safely handle the descaling agent  310 . 
     Reference will now be made to  FIGS. 7-9 , which show a (alternative) descaler chamber  705  and a (alternative) descaler container  710  according to an alternative embodiment of the present invention. 
     The descaler chamber  705  and the descaler container  710  differ from the descaler chamber  192  and from the descaler container  305 , respectively, in what follows. 
     From a free periphery of the support element (differentiated with the reference  715  in  FIGS. 7-9 ) of the descaler chamber  705  a hollow punching element  720  is provided. Advantageously, the hollow punching element  720  protrudes from the free periphery of the support element  715  substantially transversal to the latter (i.e., parallel to inner sidewall  725  of the housing portion—differentiated with the reference  730  in  FIGS. 7-9 —of the descaler chamber  705 ) towards the top aperture (differentiated with the reference  735  in  FIGS. 7-9 ). Preferably, the hollow punching element  720  is made integral with the support element  715 . In this embodiment of the present invention, the hollow punching element  720  substantially delimits the aperture (differentiated with the reference  736  in  FIGS. 7-9 ). 
     Preferably, the hollow punching element  720  has a substantially C-shape in plain view (not shown) and an inclined profile in cross-sectional view. Preferably, the hollow punching element  720  has (in cross-sectional view) low portions  720   a  (corresponding to the tips of the “C”, only one of which visible in the figures) flushing with the support element  715  and a top portion  720   b  (corresponding to the bend portion of the “C”) protruding from the support element  715  up to a predetermined distance (preferably equal to the length of the container neck—differentiated with the reference  740  in  FIG. 7 ) towards the inside of the housing portion  730 . A free end of hollow punching element  720  defines a cutting edge thereof, which is adapted to cut a (alternative) container cap  745  of the descaler container  710 . 
     The container cap  745  of the descaler container  710  is made of a water-resistant material adapted to confine the descaling agent (differentiated with the reference  750  in  FIG. 7 ) within the container. For example, the descaler cap  745  may be made of a foil of aluminum coupled with the container body (differentiated with the reference  752  in  FIG. 7 ), e.g., the descaler cap  745  may be glued to a rim of the container neck  740 . 
     When the user inserts the descaler container  710  in the housing portion  730  of the descaler chamber  705  the cutting edge of the hollow punching element  720  cuts the descaler cap  745 . Advantageously, the hollow punching element  720  leaves a sliver of the descaler cap  745  attached to the container neck  740  (i.e., between the lower portions  720   a ), thus preventing the descaler cap  745  to fall into and possibly clog the descaler chamber  705 . 
     Preferably, the hollow punching element  720  has a diameter substantially corresponding to a diameter of the aperture (differentiated with the reference  755  in  FIGS. 7-9 ) of the descaler container  710 . Therefore, the hollow punching element  720  cuts the descaler cap  745  close to the container neck  740  of the container body  752 . Thanks to the inclined profile of the hollow punching element  720  (described above), a sliver  745   a  of the descaler cap  745  remains attached to the container neck  740 . In this way, the weight of the descaling agent  750  within the descaler container  710  makes the descaler cap  745  (between the low portions) pivot on the sliver  745   a  towards the mixing portion (differentiated with the reference  760  in  FIG. 7 ) of the descaler chamber  705 . Thus, the descaling agent  750  pours down in the mixing chamber  760  through the container aperture  755 . The positioning of the descaler container  710  in the housing portion  730  is completed by closing the top aperture  735  with the cap (differentiated with the reference  765  in  FIG. 7 ). In this embodiment of the present invention, the nozzle (differentiated with the reference  770  in  FIG. 7 ) sprays water in the descaler container  710  thus removing any descaling agent  750  possibly remained inside the descaler container  710 , and then falls into the mixing portion  760  where it mixes with the descaling agent  750 . 
     It should be readily apparent to those skilled in the art that the descaling procedure  600  described above may be implemented in dishwasher comprising the alternative descaler chamber  705  and the alternative descaler container  710 , without requiring substantial changes to the descaling procedures  600 . 
       FIG. 10  is a schematic partial cross-sectional view of a further dishwasher  1000  wherein a further alternative descaler chamber  1005  according to a further embodiment of the present invention is provided adapted to the use with the descaler container  305 . 
     The descaler chamber  1005  differs from the descaler chamber above described in what follows. 
     The descaler chamber  1005  is positioned in the dishwasher  1000  in such a way that its top aperture  1010  is completely accessible from the outside of dishwasher  1000 . Preferably, the descaler chamber  1005  is provided beneath a washing chamber  1015  and a loading/unloading aperture  1020  of the dishwasher  1000 . The top aperture  1010  of the descaler chamber  1005  is preferably flush with a front panel  1025  of a casing  1030  of the dishwasher  1000 . 
     In one embodiment of the invention, the descaler chamber  1005  is slanted with respect to a plane defined by the front panel  1025  of the casing  1030 . Thanks to such a slanted position of the descaler chamber  1005 , the descaling agent  310  in the descaler container  305 , once housed in a housing portion  1032  resting on the support element  1034  of the descaler chamber  1005  completely falls in a mixing portion  1035  of the descaler chamber  1005  once a water spray sprayed from a nozzle  1040  removes the container cap  1035  from the descaler container  1005  inserted (similarly as above described) in the housing portion  1032  of the descaler chamber  1005 . 
     Preferably, although not limitatively, the mixing portion  1035  is provided with a manifold  1045 , even more preferably substantially funnel-shaped, connected to an outlet pipe (differentiated with the reference  1098  in  FIG. 10 ) in order to feed the descaling liquid to the hydraulic circuit of the dishwasher  1000  (allowing performing the descaling procedure  600  as described above). 
     The position of the descaler chamber  1005  and of the top aperture  1010  thereof allows an easier insertion of the descaler container  305  in the housing portion  1032  of the descaler chamber  1005 , particularly without the need for the user to access the washing chamber  1015 . 
     In order to close the top aperture  1010  of the descaler chamber  1005  a corresponding lid (not shown) may be provided. Preferably, such lid flushes with the front panel  1025  of the dishwasher  1000 , once it closes the top aperture  1010  of the descaler chamber  1005 . Also in this case the lid may be either a removable lid or a hinged lid. 
     In a further alternative embodiment of the present invention, a further alternative descaler chamber is provided, analogous to the one just described with reference to  FIG. 10  but featuring a hollow punching element protruding from a free end of the support element, thus adapted to be used with the alternative descaler container  710  having a water-resistant container cap  745 . 
     It should be readily apparent to those skilled in the art that the descaling apparatus  190  according to any embodiment of the present invention is also adapted for the use with a descaling agent (either in liquid or solid form) not stored in a container, referred to as unpackaged descaling agent in the following. Indeed, the unpackaged descaling agent may be introduced in the descaler chamber  192 ,  705 , and  1005  manually by the user, in a predetermined amount. Such unpackaged descaling agent once introduced in the descaling chamber  192 ,  705 , and  1005  falls down directly into the mixing chamber  225 ,  745 , and  1035  thereof. After having dispensed the unpackaged descaling agent, the user may close the lid  193 ,  765  and complete the descaling procedure  600  as above described. In other words, the descaling apparatus  192  is not limited to the use with a descaler container  305 ,  710 , but it is able to correctly operate also with any type of unpackaged descaling agent without requiring any structural changes thereto.