Patent Description:
In electrical household appliances having a boiler in which water boils, limescale or calcium carbonate is deposited on the walls of the boiler in the form of coatings and of sediment. When the amount of sediment and limescale coatings is significant, a foam is generated by action of the steam bubbles and can be expelled from the boiler. In the exemplary case of an ironing device, limescale can even close the solenoid control valve or settle on the fabric leaving unpleasant spots.

Limescale accumulated within the boiler needs to be periodically cleaned to avoid these drawbacks. For example in an ironing device, it is usually recommended to clean the boiler each ten uses by rinsing its interior. It is not possible to properly remove limescale just by cleaning the interior of the boiler, since limescale accumulates more and more adhered to walls and above all to the inner wall.

Document <CIT> describes an electrical household appliance comprising a boiler, in which water is brought to a boil, which has an opening in a wall closable by a stopper and a device for removing limescale formed in the boiler being extractable through the opening in the wall of the boiler. The device for removing limescale is made as at least one elastic element of a porous structure to which limescale adheres and which can be extracted from the boiler to be cleaned.

Said system has a limited effectiveness, since the cleaning of the porous device is difficult when the pores inside it are loaded with limescale.

Patent application <CIT> relates to a device for heating a liquid comprising an elongate heating element which extends in the liquid for the purpose of producing vapour, and wherein an antifouling, particularly antiscale, device is arranged on this elongate heating element, said antiscale device comprising a series of parts which are rolled around the heating element.

International patent application <CIT> relates to a boiler for generating steam and/or for heating water, the boiler comprising at least one collector device, which is partly immersed in the water, to aggregate and retain limescale that forms inside the boiler during used.

The object of the present invention is to provide an electrical household appliance with a boiler, in which water is brought to a boil and including a device to remove more easily limescale formed by boiling water inside the boiler, thereby extending its lifetime.

To this end, the invention relates to an electrical household appliance comprising a boiler, in which water is brought to a boil, which has an opening in a wall closable by a stopper and a device for removing limescale formed in the boiler that can be extracted through the opening in the wall of the boiler. The device has at least one elastic element having a helicoidal shape, in particular, the shape of a spring, to which limescale can adhere and, once extracted from the boiler, limescale can be removed from it when necessary, being possible to manipulate it so as to remove the collected limescale. The device can be formed by one or several elastic elements. Having a helicoidal structure, it can be handled more easily and you can access its entire surface for its complete cleaning. Furthermore, the volume it occupies inside the boiler is smaller and does not reduce significantly the water capacity in the boiler.

The size of the device is such that its surface area has an appropriate ratio to the inner wall of the boiler so it can be inserted through an opening of the same, not necessarily a discharge opening but made to insert and extract the device for cleaning purposes. Generally speaking, the external shape of the helicoidal elastic element can be cylindrical, square, rectangular, conical, pyramidal or another regular (or irregular) shape that facilitates mobility of the helicoidal element inside the boiler. It is preferably tubular to facilitate manipulation and compression as well as to provide a bigger limescale collecting area.

In an example not forming part of the present invention, in order to facilitate the drainage of the boiler and the extraction of the device to remove limescale, it is provided that the opening is arranged at or near the lower part of the boiler. However, it may also be the case that the opening is a water-filling opening and, for that reason, it is preferably arranged in the top part of the boiler. In this manner, no additional opening is required for draining and inserting and extracting the device to remove limescale.

In the example not forming part of the invention it is provided that the device is joined to the stopper. In this manner, when the closing stopper of the boiler is removed, the device is pulled outwards, thereby facilitating its extraction. The device can be joined to the stopper by means of a flexible connection in the manner of a chain long enough so that the device is sunk by its own weight on the lowest part of the boiler. Otherwise, if the stopper is in the highest part of the walls of the boiler, the device can be kept suspended centred inside the boiler. In this manner, warm water currents flowing up to the top part of the boiler will flow through the wire of the device leaving more limescale rests. Several of these elastic elements can be introduced into the boiler joined together like necklace pieces that go behind the stopper when you pull it to carry out their cleaning.

Furthermore, the device can be fixedly connected to the stopper. Here, it is preferable that the stopper is arranged in the lower part of the boiler, being centred and covering a significant part of the lower surface of the boiler to keep it sunk and having more contact with boiled water flowing up to the top part of the boiler.

By using metal and/or plastic wire, you can obtain a considerably resistant device, where the required ratio to the size of the boiler can be achieved with a small device. Thus, as an example for a medium-sized boiler of two-litre capacity, a cylindrical tubular device (with or with no central hole) does not need to exceed dimensions in the order of <NUM> or less of diameter and axial length.

Said helicoidal elastic element can be made of stainless steel wire or another anticorrosive metal such as monel, nickel or aluminium or also of a plastic such as POM, PC and/or PEK made by means of an extrusion process. The temperature it needs to resist is higher than <NUM>, amounting to about <NUM> when the pressure inside the boiler reaches <NUM> bar, about <NUM> at <NUM> bar, <NUM>° C at <NUM> bar and even above <NUM> when the pressure reaches <NUM> bar inside the boiler. The wire of the elastic element can be a wire of a circular section, what makes the limescale collecting capacity increase.

It is also provided that at least a part of the elastic element can be compressed in at least a lineal direction and/or in a curved line. This makes it convenient to manually compress and clean it.

According to the invention, in order to make a device having a firm structure, it is provided that the device has a guide surrounded at least partially by the elastic element. The guide helps align the elastic element when it is compressed during its cleaning and for its insertion into the boiler.

In order to limit the movement of the elastic element outside the guide, this has two stops and the elastic element is arranged in such a manner that it can be moved between both stops.

If the guide is joined to the stopper, one of the stops is the stopper and the elastic element is joined to the stopper. In this manner, the other end of the elastic element can remain free without needing another stop in the guide. Otherwise, if the guide has another stop, the elastic element can remain freely arranged between the stopper and the stop.

The guide can be a rigid longitudinal element around which the helicoidal elastic element is arranged. When it is spring-shaped, the elastic element is cylindrical to a great extent having a reduced diameter in its ends for a better limitation by the stops of the guide.

The wire of the helicoidal elastic element has a thickness of preferably <NUM> to <NUM>, preferably of <NUM>. The thicker the wire is, the less flexible and more difficult to be cleaned it is. The thinner it is, the more delicate and more susceptible to get damaged when being handled it is. The width of the helicoidal passage can amount to <NUM> to <NUM>, preferably to about <NUM> having a clear passage of <NUM> when the wire is <NUM> thick. A big passage reduces the limescale collecting capacity.

In the example not forming part of the invention the elastic element may even have such a length that it extends inside the boiler bending and winding on itself.

According to the invention,
the elastic element is mounted on a guide in the manner of a rigid bar and the maximum length of the elastic element will be determined by the distance from wall to wall of the boiler. The longer the elastic element is, the higher its limescale collecting capacity will be. A shorter length is acceptable to facilitate the insertion and extraction into/from the boiler. An acceptable limescale collection is already achieved with lengths of the elastic element from <NUM>. The biggest outer diameter of the helicoidal elastic element is determined by the diameter of the opening. Without being understood as a limitation, an opening from <NUM> to <NUM> is usual in this kind of boilers, although it can even be bigger. Then, the diameter of the elastic element must be a bit smaller so as to facilitate its insertion and extraction.

A device for removing limescale according to the invention is used in electrical household ironing appliances, which have a boiler in which water is brought to a boil for the steam generation that is connectable to an iron or another ironing device. The boiler of this type of appliances is a closed boiler that works under pressure and which is difficult to access for its internal cleaning. Therefore, a cleaning device like the one of the invention, which can move inside the boiler and filters the limescale particles from water boiling inside it, extends the lifetime of these appliances and avoids that limescale rests can get out of the boiler through the wire connecting to the iron and stain the clothes during the ironing function.

Another object of the invention is a device for removing limescale from a boiler of an electrical household appliance according to the invention. This device is connectable to a stopper of the boiler and can be connected in a movable or unmovable manner relative to the stopper. In addition to that, it can be mounted and demounted to/from the stopper to be cleaned. Furthermore, the device comprises at least a helicoidal elastic element so that limescale adheres to its surface and, once extracted from the boiler, it can be cleaned, rinsed with water or some anti-limescale chemical product.

Other advantages derive from the following description of the figures. In the figures, an example of an embodiment of the invention is represented. The figures, the description and the patent claims contain many features in combination. The person skilled in the art shall advantageously consider these features also individually and gather them in other reasonable combinations. These show in:.

<FIG> shows an example of a boiler <NUM> of an electrical household appliance (not shown in its entirety in the figure) which is not part of the invention. It has a cut-out in one of its walls <NUM> to see its inner part. Inside it, a heating element <NUM> can be seen, which bends to have more contact with the water to be boiled.

In the top wall <NUM> of the boiler <NUM>, there is an opening <NUM> to drain the boiler <NUM> and which can also work as a filling opening for filling water into the boiler <NUM> in the case of the type of boiler with no water supply when it is hot. This opening <NUM> is closable by a stopper <NUM> with a hermetic closure withstanding the pressure generated inside the boiler <NUM> when the heating element <NUM> is working.

In the top wall <NUM> of the boiler <NUM>, there is also an outlet port <NUM> of the steam of the boiler <NUM> to the steam ejection device (not shown), which can be a clothes iron or a vaporizer. This connection between the boiler <NUM> and the steam ejection device is usually regulated by an electrovalve to dose steam.

A device <NUM> to remove limescale that precipitates from boiling water is arranged inside the boiler <NUM>. This device <NUM> is composed of three helicoidal elastic elements <NUM> connected to each other by sections of rope or chain. The length of the rope section connecting the elastic element <NUM> to the stopper <NUM> is long enough so that the elastic element <NUM> is near the bottom wall <NUM> of the boiler <NUM>. The rest of the elastic elements <NUM> connect to each other. The biggest diameter of the elastic elements <NUM> is similar to or smaller than that of the opening <NUM> to ease their extraction.

By means of the example of <FIG> which is not part of the invention, a device <NUM> is disclosed with elastic elements <NUM> having free movement inside the boiler <NUM> which, when they are inserted into a water-boiling boiler <NUM> or another vessel to which they are specifically adapted, tend to collect limescale (precipitated from the water in the boiler <NUM>) in the wire forming the elastic elements <NUM> due to their movement inside the boiler <NUM>. After a suitable utilization of the elastic elements <NUM>, they can be extracted from the boiler <NUM> vessel and softly manipulated with the user's hand to remove the retained limescale. If this cleaning is carried out on a regular basis and the wire is made of stainless steel or another permanent anticorrosive material (that may include a plastic substance), lifetime of the electrical household appliance can be extended considerably.

<FIG> shows a schematic view of a boiler <NUM> of an electrical household appliance (not entirely shown in the figures) according to the invention having a circular base and whose top wall cannot be seen, in which the water inlet and the steam outlet are arranged, so as to see into the boiler <NUM>. A heating element <NUM> is integrated into the base of the boiler <NUM> to heat and boil water.

An opening <NUM> is provided in the side wall <NUM> of the boiler <NUM>, which is hermetically closable by a stopper <NUM> that withstands the pressure generated by the steam inside the boiler <NUM> when the heating element <NUM> is working. This opening <NUM> is a drainage opening of the boiler <NUM> in the case of electrical household appliances with water supply when the boiler <NUM> is hot. In the case of this type of appliance, the drainage opening <NUM> is to be opened only when the boiler <NUM> is cold.

A device <NUM> to collect limescale that precipitates from water is arranged inside the boiler <NUM>. This device <NUM> is made as a helicoidal elastic element <NUM> in the form of a spring, for example of stainless steel wire fixedly connected to the stopper <NUM>. When the stopper <NUM> is opened, the part of the device <NUM> remaining inside the boiler <NUM> can be extracted from inside the boiler <NUM> together with the elastic element <NUM>. It is preferred that the device <NUM> is arranged being mounted on the bottom part of the boiler <NUM>.

Claim 1:
An electrical household appliance comprising:
- a boiler (<NUM>) having a circular base, in which water is brought to a boil, which has an opening (<NUM>) in a wall (<NUM>) closable by a stopper (<NUM>),
- a heating element (<NUM>) integrated into the base of the boiler (<NUM>) to heat and boil water, and
- a device (<NUM>, <NUM>) for removing limescale formed in the boiler (<NUM>), said device (<NUM>, <NUM>) being extractable through the opening (<NUM>) in the wall (<NUM>) of the boiler (<NUM>),
wherein the device (<NUM>, <NUM>) has at least one elastic element (<NUM>) having a helicoidal shape, in particular, the shape of a spring, to which limescale can adhere and, once extracted from the boiler (<NUM>), limescale can be removed from it;
characterized in that the device (<NUM>, <NUM>) is movable inside the boiler (<NUM>), and is configured to filter the limescale particles from water boiling inside it;
wherein the device (<NUM>, <NUM>) has a guide (<NUM>) surrounded at least partially by the elastic element (<NUM>);
and wherein the electrical household appliance is an iron for clothes.