EP1774224B1

EP1774224B1 - Steaming device, particularly for electric household appliances

Info

Publication number: EP1774224B1
Application number: EP04745210A
Authority: EP
Inventors: Daniele De Rossi
Original assignee: Dierre Finanziaria SpA
Current assignee: Dierre Finanziaria SpA
Priority date: 2004-07-12
Filing date: 2004-07-12
Publication date: 2010-10-27
Anticipated expiration: 2024-07-12
Also published as: DE602004029824D1; ATE486247T1; WO2006006187A1; EP1774224A1

Abstract

The invention relates to a steaming device (1), particularly for irons or other steam electric household appliances, comprising: a tank (2) having a water inlet opening and a steam outlet opening; a bottom wall (2a) placed inside the tank (2) having a first (9) and a second (10) portion; and heating means (5) associated to the bottom wall (2a). The first portion (9) and the second portion (10) are separated by a partition wall (11). The first portion (9) receives a higher thermal energy pro surface unit than the thermal energy in the second portion (10), so as to turn water into steam more rapidly.

Description

The present invention relates to a steaming device, particularly for common electric household appliances such as irons or floor cleaners.
Generally, such devices are equipped with a boiler comprising a tank containing water to be turned into steam. The boiler can be integrated into the aforesaid electric appliance or it can be separate from the latter and connected to it through suitable steam pipes. More to the point, the tank is connected to a water supply duct, which supplies water into said tank. The duct is equipped with a supply pump connected to a thermostatic switch arranged inside the tank.
When water inside the tank is fully turned into steam, the switch activates and turns on the supply pump so that it supplies again water to the tank.
The boiler is thus cyclically filled up with water whenever it is fully emptied.
Water inside the tank is heated by means of an electric resistance normally arranged under a bottom wall of the tank.
Moreover, the tank is provided with a steam outlet opening connected to the steam pipe, which as was mentioned above is associated to the corresponding electric appliance.
As a rule, suitable control elements are further arranged, which act upon the steam pipe and can be managed directly by the user so as to close or open the aforesaid pipe.
Document EP-A-0 821 096 describes a steaming device according to the preamble of claim 1. Said known technique has some important drawbacks. First of all, it should be noted that the amount of steam provided by the boiler is not always constant. As a matter of fact, between a boiler filling cycle and the following one, water introduced by the pump (cold water) should be heated up to the optimal evaporation temperature. Water heating causes a given waiting time in which no steam is generated. Therefore, the introduction into the boiler of large amounts of cold water at every refilling through the pump clearly alters the conditions inside the boiler and creates dead times due to delays occurring for heating up said amount of cold water to the required temperature. Moreover, water level and therefore steam volume in the upper portion of the boiler undergo quite broad oscillations, which do not allow to keep constant pressure and temperature features of the steam to be sent to the user appliance. It should be pointed out that it is particularly important for almost all domestic uses to have steam with constant properties. Under these circumstances, the technical task underlying the present invention is to conceive a steaming device that can basically obviate the aforesaid drawbacks.
In the framework of said technical aim, an important aim of the invention is to conceive a steaming device that enables to keep a constant water level in the boiler it is provided with, so that the supplied steam has always unchanged properties.
Another important aim of the invention is to conceive a steaming device in which heating times are further reduced with respect to the state of the art thanks to an automatic refilling of water into the boiler.
The technical task and the aims referred to above are basically achieved by a steaming device, particularly for electric household appliances, comprising the features described in the appended claims.
The following contains by way of non-limiting example the description of a preferred but not exclusive embodiment of a device according to the invention, as shown in the accompanying drawings, in which:

Figure 1 shows a schematic view in lateral elevation, partially sectioned, of a steaming device according to the invention;
Figure 2 shows a plan view from below of a construction detail of the device shown in Figure 1;
Figure 3 shows a sectioned view in lateral elevation of a construction detail of Figure 1 according to a second embodiment.

With reference to the aforesaid figures, the steaming device according to the invention is globally referred to with number 1.
The device 1 comprises a tank 2 defining a closed chamber 3 housing inside water to be turned into steam. In particular, said tank 2 has a flat bottom wall 2a having a basically horizontal development so as to collect water introduced into the chamber 3.
It should be pointed out that the accompanying figures show a basically cylindrical tank 2 whose bottom wall 2a has a peripheral circular development. It should however be noted that said shape is a mere non-limiting example and, therefore, the tank 2 and the bottom wall 2a can have any shape in accordance with the various construction requirements.
The device 1 further has at least one outlet opening 4 for sending the generated steam to a user electric household appliance, not shown in Figure 1, for instance an iron.
The outlet opening 4 is advantageously associated to the tank 2 above the aforesaid bottom wall 2a and it is operatively connected to a known steam conveying duct, which shall not be described in further detail. The bottom wall 2a of the tank 2 is provided with heating means 5 supplying said bottom wall 2a with a given thermal energy per surface unit.
In particular, said heating means 5 preferably comprise an electric resistance associated to a lower surface 7 of the bottom wall 2a placed outside the chamber 3.
The electric resistance 6 can be integrated into a plate 7a made of aluminum alloy, applied outside and with heat exchange against the lower surface 7 of the bottom wall 2a.
The electric resistance 6 thus generates a thermal flow for heating the bottom wall 2a, which gets the aforesaid thermal energy per surface unit.
Advantageously, the bottom wall 2a has a first and a second water collection portion 9, 10, separate and coplanar one with respect to the other.
More to the point, the device 1 has a partition wall 11 housed inside the chamber 3 and extending from the bottom wall 2a for separating the first portion 9 from the second portion 10, thus defining two separate water reservoirs.
As shown in the accompanying figures, the partition wall 11 can be basically ring-shaped so as to surround the first portion 9. In other words, in this case the first portion 9 is arranged inside the second portion 10, which develops along the peripheral development of the bottom wall 2a.
Alternatively, the partition wall 11 can take any shape and can define the aforesaid first portion 9 together with a lateral wall of the tank 2.
In accordance with the first embodiment shown in Figure 1, the partition wall 11 includes a ring-shaped element 11a associated to the bottom wall 2a by means of suitable hooking elements, or resting on the latter. A conventional sealing gasket can further be present.
Alternatively, in accordance with the second embodiment shown in Figure 3, the partition wall 11 can be obtained from the bottom wall 2a, suitably shaped so as to obtain a projection 11b constituting the aforesaid partition wall 11.
The first and second portion 9, 10 have respective upper surfaces 8, coplanar one to the other and arranged inside the chamber 3 opposite the aforesaid lower surface 7. Advantageously, the upper surface 8 of the first portion 9 is smaller than the upper surface 8 of the second portion 10.
Under these circumstances, the electric resistance 6 mainly develops on the first portion 9, so as to generate a higher average thermal energy in the first portion than the average thermal energy in the second portion 10.
Such a situation is indeed due to the "larger" presence - in terms of occupied surface - of the resistance 6 in the first portion 9.
Moreover, in the example of Figure 2 the electric resistance 6 is basically "U"-shaped. Advantageously, the central portion of the "U"-shaped resistance is arranged on the first portion 9 of the bottom wall 2a, so as to receive a larger amount of heat with respect to its surface.
Water is introduced into the tank 2 by means of a supply source 12 operatively connected to at least one water inlet opening 13 associated to the tank 2 above the bottom wall 2a.
In accordance with an execution variant, not shown in the accompanying figures, there can be two inlet openings 13, each of them being placed above a corresponding portion 9, 10 of the bottom wall 2a. Water can thus be better supplied both in the first portion 9 and in the second portion 10.
Advantageously, the two openings 13 can be adjusted so that the flow rate of the opening placed on the second portion 10 is higher, and preferably twice as much, than the flow rate of the opening placed on the first portion 9.
The supply source 12 has a supply element 14 engaged to the inlet opening 13 for supplying water into the chamber 3. The supply element 14 is advantageously connected to a thermal sensor 15 placed in the first portion 9 and designed to detect water exhaustion through a given temperature rise. In particular, the thermal sensor 15 preferably includes a known thermostatic switch, which therefore is not described in further detail, associated to the bottom wall 2a (see Figure 2).
In further detail, the supply element 14 includes a water reservoir 16, connected to the tank 2 by means of a supply duct 17.
The supply duct 17 has a first end 17a associated to the aforesaid reservoir 16, and a second end 17b engaged to the inlet opening 13 for putting into fluid communication the reservoir 16 with the chamber 3 of the tank 2.
In the embodiment referred to above in which two inlet openings 13 are present, the duct 17 advantageously has two second ends 17b, each of them being associated to a corresponding inlet opening 13.
Thus, the water flow coming from the reservoir 16 is split up between the two second ends 17b of the aforesaid duct 17 by means of a pump 18 mounted inside the duct 17 between the first end and the second ends 17a, 17b.
More to the point, the pump 17 is controlled by a thermal sensor 15 so as to allow water to pass only when said thermal sensor detects a given temperature rise due to the substantial exhaustion of water contained in the first portion 9. Eventually, the heating means 5 further comprise an auxiliary thermal sensor 19, which preferably also includes a thermostatic switch.
As is shown in Figure 2, the auxiliary sensor 19 is arranged near the resistance 6 and is adjusted so as to interrupt electric supply to the latter upon reaching of a pre-established safety temperature.
The device for generating steam according to the invention, described above from a mainly structural point of view, works as follows.
First of all, when the tank is empty, the supply element 14 fills the chamber 3 up to a pre-established level, generating steam immediately and simultaneously to the rise of water level. As a matter of fact, the initial absence of water causes a sudden temperature rise in the first portion 9 and thus the activation of the pump 18 by the sensor 15.
The amount of water getting in through an inlet opening 13 and falling into the first portion 9 cools the upper surface 8 and rapidly heats up and evaporates, whereas the amount of water introduced into the second portion 10 of the bottom wall 2a heats up.
The cooling of the first portion 9 of the bottom wall 2a, detected by the sensor 15, makes the pump 18 stop until a new temperature rise causes a second start of the pump 18.
A series of steps of de-activation and activation of the pump 18 follows in the same way, during which the first portion 9 undergoes alternating conditions of minimum water level and partial filling, whereas water in the second portion 10 progressively rises up to the pre-established level as defined by the height of the partition wall 11 separating the two portions. As soon as water in the second portion 10 reaches the top of the partition wall 11, water in excess falls into the first portion 9 and cools its upper surface 8, thus making the pump 18 stop. The heating and evaporation of water fallen into the first portion 9 causes a new start of the pump 18, and thus steps of stop and activation of the pump 18 follow up one another, thus keeping water level in the chamber 3 constantly at the same height as the partition wall 11.
The invention has important advantages.
First of all, it should be pointed out that dead times required for heating water introduced into the chamber 3 are completely eliminated.
As a matter of fact, the first portion 9 having always a high thermal energy continuously turns water into steam, and as soon as water inside the first portion gets exhausted (minimum level), new water is introduced by means of the sensor 15. During this step, water inside the second portion heats up and is turned into steam. Advantageously, there is a continuous steam production.
Moreover, the partition wall 11 enables water to overflow from the second to the first portion, so as to keep a basically constant water level in the chamber 3, thus obtaining steam with accordingly constant properties.
The high sensibility of intervention of the sensor 15, obtained using water falling into the first portion 9 through the partition wall 11, allows to refill a very small amount of water into the chamber 3, thus reducing heating and evaporation times.
Eventually, it should be pointed out that the device according to the invention enables a simple and accurate control of water level in the chamber 3, thus reducing tank size though generating steam with constant properties.

Claims

A steaming device (1), particularly for electric household appliances, comprising:
- a tank (2) defining a closed chamber (3) and having a flat bottom wall (2a) having a basically horizontal development for collecting water;

- at least one water inlet opening (13) associated to the tank (2) above said bottom wall (2a) and operatively connected to a water supply source (12);

- at least one steam outlet opening (4) associated to the tank (2) above said bottom wall (2a) and apt to be operatively connected to a household appliance for supplying the latter with steam; and

- heating means (5) associated to the bottom wall (2a) of the tank (2), wherein said bottom wall (2a) is provided with said heating means (5) for supplying a given thermal energy per surface unit to said bottom wall (2a), characterized in that said bottom wall (2a) has a first and a second portion (9, 10) for water collection, separate and basically coplanar one with respect to the other, the first and second portion (9, 10) having respective upper surfaces (8) coplanar one to the other and arranged inside said chamber (3) opposite a lower surface (7) of said bottom wall (2a); the average thermal energy pro surface unit supplied by said heating means (5) to the first portion (9) being higher than the average thermal energy pro surface unit supplied to the second portion (10), and in that it further comprises a thermal sensor (15) operatively associated to the bottom wall (2a) on said first portion (9).
The device according to claim 1, characterized in that said heating means (5) have at least one electric resistance (6) engaged to said lower surface (7) of the bottom wall (2a) placed outside said chamber (3).
The device according to claim 2, characterized in that said electric resistance (6) mainly develops on said first portion (9).
The device according to claim 2, characterized in that said electric resistance (6) is basically "U"-shaped, said first portion (9) being arranged on a central portion of said "U".
The device according to any of the preceding claims, characterized in that the upper surface (8) of the first portion (9) is smaller than the upper surface (8) of the second portion (10).
The device according to any of the preceding claims, characterized in that it comprises a partition wall (11) for separating the first portion from the second portion (9,10).
The device according to claim 6, characterized in that said partition wall (11) extends from said bottom wall (2a) and is integral with the bottom wall (2a).
The device according to claim 6, characterized in that said partition wall (11) includes a ring-shaped element (11a) associated to the bottom wall (2a) and a sealing gasket placed between the ring-shaped element (11a) and the bottom wall (2a).
The device according to any of the preceding claims, characterized in that said thermal sensor (15) is a thermostatic switch.
The device according to claim 9, characterized in that said water supply source (12) comprises a supply element (14) engaged to said inlet opening (13) for supplying water into said chamber (3); said element (14) being operatively connected to said thermal sensor (15).
The device according to claim 10, characterized in that said supply element (14) comprises:
- a water reservoir (16);

- a supply duct (17) having a first end (17a) associated to said reservoir (16) and a second end (17b) engaged to said water inlet opening (13) for putting into fluid communication the reservoir (16) with said chamber (3) of the tank (2); and

- a pump (18) arranged between said first and second end (17a, 17b) of the duct (17) and operatively connected to said thermal sensor (15) for conveying water from the reservoir (16) to the chamber (3) when said sensor (15) detects a minimum water level in said first portion (9).
The device according to the preceding claim, characterized in that it comprises two water inlet openings (13), each being placed above a corresponding portion (9, 10) of the bottom wall (2a); said supply duct (17) having two second ends (17b), each being associated to a corresponding opening (13).
The device according to any of the preceding claims, characterized in that said heating means (5) further comprise an auxiliary thermal sensor (19) adjusted to a safety temperature for interrupting electric supply to said electric means (5).
The device of claim 6, wherein the partition wall (11) is basically ring-shaped so as to surround the first portion (9), the first portion (9) being arranged inside the second portion (10), which develops along the peripheral development of the bottom wall (2a).