WO2017174712A1

WO2017174712A1 - Boiler

Info

Publication number: WO2017174712A1
Application number: PCT/EP2017/058232
Authority: WO
Inventors: Giuseppe De' Longhi; Antonio Lorenzon; Laura DURANTE
Original assignee: De' Longhi Appliances S.R.L. Con Unico Socio
Priority date: 2016-04-06
Filing date: 2017-04-06
Publication date: 2017-10-12
Also published as: ITUA20162359A1; EP3440410B1; ES2828056T3; CN109312931A; EP3440410A1; CN109312931B

Abstract

Boiler to generate steam and/or to heat water, comprising a metal container (12) provided with at least a feed aperture (14) to introduce water inside it. The boiler comprises a heating element (18) associated to the container (12), and at least one detection device (20) to detect the physical quantities inside the container (12), positioned in correspondence with at least one detection zone (22) on an external surface (24) of the container (12).

Description

"BOILER"

FIELD OF THE INVENTION

The present invention concerns a boiler to generate steam and/or to heat water, usable in domestic appliances and professional machines such as, for example, ironing or cleaning apparatuses, coffee machines, steamers for cooking food, steam ovens and suchlike.

BACKGROUND OF THE INVENTION

Boilers used to selectively generate steam and/or to heat water in domestic appliances and professional machines normally comprise a metal container, hermetically closed, provided with at least an entrance aperture for the water and, possibly, an exit aperture for the steam.

Some types of boiler can also comprise a discharge aperture to empty the water from the container, in order to clean or inspect it.

A heating element is normally associated with the metal container, generally an electric resistance or plate, selectively activated to generate the desired quantity of steam and/or to take the water to the desired temperature.

Boilers normally comprise one or more detection devices to detect the temperature and/or pressure inside the metal container, so as to monitor them and prevent them from exceeding determinate threshold values which can damage the metal container and the boiler itself.

It is known that, when the boiler is used and due to heating the water, formations of limescale are generated inside the metal container, consisting of calcium carbonate and/or other minerals such as magnesium, potassium and silicon, normally dissolved in the water.

These formations of limescale can deposit and form incrustations of increasing thickness on the internal walls of the metal container.

One problem that these formations of limescale can cause is that, since the devices to detect the temperature and/or pressure are generally installed outside the metal container, the detection can be influenced by the presence of limescale deposited on a portion of the internal surface opposite the external portion where they are positioned.

Indeed, the minerals that the incrustations of limescale consist of are heat insulating, and therefore they can delay or distort the detection of the temperature and/or pressure inside the metal container.

An incorrect, or delayed, detection of the temperature and/or pressure can lead to the safety threshold values being exceeded, and hence can damage the boiler.

If the incrustations are deposited precisely in correspondence with the assembly position of the heat detection devices, malfunctions of the boiler can therefore occur, which can reduce the useful working life thereof.

Document WO 01/94861 describes a water heating container inside which a tubular heating element with an elongated shape is disposed. The container provides an aperture to feed the water and an aperture through which the heated water comes out. The feed aperture is directly connected to the tubular heating element through which the water passes and is heated.

The heating element consists of a pipe on which the electric heating resistances are printed. With the same technology, temperature detection sensors can be printed on the wall of the pipe.

The tubular heating element also has a layer of internal coating material which coats it completely, for example polypropylene, which inhibits the deposit of limescale.

Document EP 2.886.024 describes a detection devices for an oven. The detection device is installed partly inside a cooking chamber.

One purpose of the present invention is to supply a boiler to generate steam and/or to heat water that allows to monitor constantly and effectively over time the temperature and/or pressure inside the metal container.

Another purpose is to supply a boiler to generate steam and/or to heat water that allows to make a detection of the temperature inside the metal container that is not influenced by the possible formation of incrustations of limescale inside the metal container itself.

Another purpose is to supply a boiler to generate steam and/or to heat water that is simple and economical but at the same time is reliable and long-lasting. Another purpose is to perfect a method for producing a boiler to generate steam and/or to heat water that is simple, economical and makes the boiler reliable and long-lasting.

The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the independent claims, while the dependent claims describe other characteristics of the invention or variants to the main inventive idea.

In accordance with the above purposes, a boiler to generate steam and/or heating water comprises a container, defining a compartment for containing the water, provided with at least a feed aperture to introduce the water inside it.

The boiler also comprises a heating element associated with the container, outside and/or inside the containing compartment, and at least a device to detect the physical quantities, such as temperature and/or pressure, inside the container, positioned on an external surface of the container.

According to some embodiments, the at least one detection device can be installed on a lateral external surface of the container, and/or on a bottom external surface of the container, in correspondence with at least one detection zone.

By detection zone we mean a zone inside the container where a physical quantity can be measured to monitor the temperature and/or pressure inside the container, to verify that they remain inside a predetermined range and/or to control the values of the steam exiting, to avoid exceeding safety values and to prevent damage to the boiler.

According to one aspect of the present invention, the container is provided, on an internal surface thereof, with at least an auxiliary coating, applied only in correspondence with the at least one detection zone in correspondence with which, on the external side, the at least one detection device is positioned.

The auxiliary coating is made of a material suitable to inhibit the formation of limescale on the portion of internal wall of the container where it is applied.

In this way, the part of the internal surface of the container not protected by the auxiliary coating can be covered by limescale, thus preventing the limescale from remaining in suspension and from coming out of the container together with the water, which could occlude the emission and regulation devices and/or the hydraulic circuit through which the steam exits. By auxiliary coating we mean a coating that can be applied directly on the internal surface of the metal container, or above possible other coatings generally used to refine and complete a metal container.

The function of the auxiliary coating is to prevent, or at least reduce, the formation of incrustations of limescale in the zones affected by the control carried out by the detection device. In this way, the detection device, not being influenced, or being less influenced, by the deposits of limescale, can detect effectively, also over time, the physical quantities inside the boiler, thus limiting the risk of malfunctions and/or breakdowns.

According to some embodiments, the auxiliary coating is made of a material with anti-adherent properties, suitable to prevent, or at least limit, the formation and deposit of limescale upon it.

According to some embodiments, the auxiliary coating is made of a material with low porosity and good chemical stability, which make it difficult for the limescale or other chemical substances to attack.

According to some embodiments, the auxiliary coating is made by painting or pad printing a material with a ceramic base, or other suitable material.

According to some embodiments, the auxiliary coating is made of a material with a sol-gel base.

According to some embodiments, the auxiliary coating is made of polytetrafluoroethylene (PTFE).

According to some embodiments, the auxiliary coating can comprise one or more layers of material.

According to some embodiments, the detection device can comprise one or more NTC (Negative Temperature Coefficient) thermistors, and/or PTC (Positive Temperature Coefficient) thermistors, installed on the lateral external surface, to detect the temperature of the water or steam inside the container.

According to other embodiments, the detection device can comprise one or more heat sensors positioned on the bottom external surface, in correspondence with determinate areas of the heating element, to monitor the functioning of the latter.

According to some embodiments, an auxiliary coating can be provided in correspondence with each of the heat detection devices and the heat sensors. The present invention also concerns a method to make a boiler to generate steam.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other characteristics of the present invention will become apparent from the following description of some embodiments, given as a non-restrictive example with reference to the attached drawings wherein:

- fig. 1 is a perspective view of a boiler to generate steam and/or to heat water according to embodiments described here;

- fig. 2 is a partly sectioned perspective view of the boiler in fig. 1 at a different angle;

- fig. 3 is a section view along plane π of the boiler in fig. 1.

To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one embodiment can conveniently be incorporated into other embodiments without further clarifications.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

We shall now refer in detail to the various embodiments of the present invention, of which one or more examples are shown in the attached drawings. Each example is supplied by way of illustration of the invention and shall not be understood as a limitation thereof. For example, the characteristics shown or described insomuch as they are part of one embodiment can be adopted on, or in association with, other embodiments to produce another embodiment. It is understood that the present invention shall include all such modifications and variants.

Embodiments described here with reference to figs. 1-3 concern a boiler 10 to generate steam and/or to heat water, usable in electric appliances and professional machines such as, for example, apparatuses for ironing or cleaning, coffee machines, steamers for cooking food, steam ovens and suchlike.

The boiler 10 comprises a metal container 12 defining a compartment able to contain the water to be transformed into steam, hermetically closed and provided with a feed aperture 14 to introduce the water inside.

According to some embodiments, the container 12 comprises a first shell 12a and a second shell 12b, coupled and hermetically sealed with each other along the respective peripheral edges, so as to resist the pressure generated inside the container 12.

According to possible solutions, described for example with reference to figs. 1-3, the first shell 12a is a lower shell, while the second shell 12b is an upper shell.

The container 12 can also be provided with an exit aperture for the steam, connected to devices to emit and regulate the steam 16.

According to some embodiments, the container 12 can also be provided with a discharge aperture 28 to empty the container 12 and/or to remove possible limescale.

The boiler 10 comprises a heating element 18 associated with the container 12 and configured to heat the water inside the latter.

According to some embodiments, the heating element 18 can be an electric resistance or an electric plate, positioned in contact with the external bottom of the container 12.

According to other embodiments, described for example with reference to fig. 3, a heating element 18 can be provided, as an alternative or in addition, located at least partially inside the container 12, in direct contact with the water to be heated.

The boiler 10 also comprises one or more detection devices 20 configured to detect the temperature and/or pressure inside the container 12 and disposed on an external surface 24 of the container 12, positioned in correspondence with determinate detection zones 22.

According to embodiments described with reference to figs. 1-3, the detection devices 20 are preferably disposed on an external surface 24 of the lower shell 12a.

According to some embodiments, the detection devices 20 can comprise heat detection devices such as NTC (Negative Temperature Coefficient) thermistors, or PTC (Positive Temperature Coefficient) thermistors, and/or heat sensors of other types.

According to some embodiments, the detection devices 20 can be positioned on a lateral external surface 24a of the container 12, to detect the temperature inside the container 12, and/or on a bottom external surface 24b of the container 12 in correspondence with determinate areas of the heating element 18, to detect the temperature of the latter.

According to one aspect of the present invention, the container 12 is provided, on an internal surface 26, with an auxiliary coating 30, applied only in correspondence with the detection zones 22 on which the detection devices 20 are disposed.

In this way, the limescale can deposit on the remaining part of the internal surface 26.

In possible solutions, the auxiliary coating 30 can be applied on an area correlated to the sizes of the one or more detection devices 20 and/or to the area needed by the detection devices 20 to detect the temperature.

For example, the area where the auxiliary coating 30 is applied can have a much smaller extension than the lateral internal surface 26a and/or the bottom internal surface 26b, for example it can be less than 10% of the extension of each of these.

This is advantageous in terms of the working life of the boiler 10, because it prevents the limescale from remaining suspended and from exiting from the boiler 10, which could occlude the hydraulic exit circuit of the steam and the devices 16 that regulate it.

In embodiments described using fig. 3, the auxiliary coating 30 can be applied on a lateral internal surface 26a, and/or on a bottom internal surface 26b of the container 12, in correspondence with the respective detection zones 22 on which the detection devices 20 are installed. The lateral internal surface 26a and/or bottom internal surface 26b are those most affected by incrustations of limescale. According to some embodiments, the auxiliary coating 30 can be made of anti- adherent material.

According to other embodiments, the auxiliary coating 30 is made of a material with low porosity and good chemical stability, which make it difficult for the limescale or other chemical substances to attack.

According to some embodiments, the auxiliary coating 30 is made by painting or pad printing.

According to variant embodiments, the auxiliary coating 30 is made by applying one or more layers of material. According to some embodiments, the auxiliary coating 30 is made of a ceramic based material, or other similar suitable material.

According to variant embodiments, the auxiliary coating 30 is made by painting or pad printing with a sol-gel based material, or is made using the sol-gel process.

According to some embodiments, the auxiliary coating 30 is made of polytetrafluoroethylene (PTFE), which can resist high temperatures and has optimum anti-adherent properties.

According to some embodiments, the auxiliary coating 30 is very thin, so that it does not create any insulating effect and/or retardant effect in detecting the temperature by the detection devices 20, thus guaranteeing a reliable detection of the temperature.

According to some embodiments, the auxiliary coating 30 has a thickness comprised between about 1 μπι and about 100 μηι.

According to other embodiments, the auxiliary coating 30 has a thickness comprised between about 20 μπι and about 90 μηι.

According to other embodiments, the auxiliary coating 30 has a thickness comprised between about 20 μπι and about 50 μπι.

It is clear that modifications and/or additions of parts may be made to the boiler to generate steam and/or heating water as described heretofore, without departing from the field and scope of the present invention.

It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of boiler to generate steam and/or heating water, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.

Claims

1. Boiler to generate steam and/or to heat water, comprising a metal container (12) defining a compartment to contain the water and provided with at least a feed aperture (14) to introduce water inside it, said boiler comprising a heating element (18) associated to said container (12), and at least one detection device (20) to detect the physical quantities inside the container (12), positioned in correspondence with at least one detection zone (22) on an external surface (24) of said container (12), characterized in that said container (12) is provided, on an internal surface (26), with at least an auxiliary coating (30), applied only in correspondence with said at least one detection zone (22) in correspondence with which, on the external side, said at least one detection device (20) is positioned.

2. Boiler as in claim 1, characterized in that said heating element (18) is disposed outside and/or inside said containing compartment.

3. Boiler as in claim 1 or 2, characterized in that said auxiliary coating (30) is made of a material with a ceramic base.

4. Boiler as in any claim hereinbefore, characterized in that said auxiliary coating (30) is made of a material with a sol-gel base.

5. Boiler as in claim 1 or 2, characterized in that said auxiliary coating (30) is made of polytetrafluoroethylene (PTFE).

6. Boiler as in any claim hereinbefore, characterized in that said auxiliary coating (30) has a thickness comprised between about 1 μηι and about 100 μηι.

7. Boiler as in any of the claims from 1 to 5, characterized in that said auxiliary coating (30) has a thickness comprised between about 20 μιη and about 90 μηι.

8. Boiler as in any of the claims from 1 to 5, characterized in that said auxiliary coating (30) has a thickness comprised between about 20 μιη and about 50 μπι.

9. Boiler as in any claim hereinbefore, characterized in that said detection devices (20) comprise NTC (Negative Temperature Coefficient) thermistors, and/or PTC (Positive Temperature Coefficient) thermistors, and/or heat sensors of another type.

10. Boiler as in any claim hereinbefore, characterized in that it comprises an exit for the steam and a discharge aperture (28) for the cleaning and the maintenance of the container (12).

1 1. Method to make a boiler to generate steam and/or to heat water (10), which provides to:

- make available a hermetically closed container (12), provided with at least a feed aperture (14) for the introduction of water inside it;

- associate a heating element (18) with the container (12);

- install at least one detection device (20) in correspondence with at least one detection zone (22) on an external surface (24) of said container (12);

characterized in that it provides to apply an auxiliary coating (30) on an internal surface (26) of said container (12) only in correspondence with said at least one detection zone (22) on which said at least one detection device (20) is positioned on the external side.

12. Method as in claim 11, characterized in that it provides to apply said auxiliary coating (30) by means of painting or pad printing of a ceramic based material, polytetrafluoroethylene (PTFE), material with a sol-gel base or other suitable material.

13. Method as in claim 11 or 12, characterized in that it provides to apply said auxiliary coating (30) with a thickness comprised between about 1 μηι and about 100 μι^η.

14. Method as in claim 11 or 12, characterized in that it provides to apply said auxiliary coating (30) with a thickness comprised between about 20 μηι and about 90 μπι.

15. Method as in claim 1 1 or 12, characterized in that it provides to apply said auxiliary coating (30) with a thickness comprised between about 20 μηι and about 50 μπι.