WO2005003627A1

WO2005003627A1 - Equipment for steam generation for household appliance

Info

Publication number: WO2005003627A1
Application number: PCT/IT2003/000425
Authority: WO
Inventors: Franco Polti
Original assignee: Polti S.P.A.
Priority date: 2003-07-07
Filing date: 2003-07-07
Publication date: 2005-01-13
Also published as: AU2003304294A1

Abstract

The present invention relates to an apparatus for generating steam, to be used in combination with a domestic electrical appliance (4), comprising a steam generator (3); a reservoir (2) for containing a fluid; a first pipe (7) for connecting the said reservoir (2) to pumping means (6); a second pipe (11) for connecting valve means (8) to the said steam generator (3); the said pumping means (6) being capable of supplying the fluid contained in the said reservoir (2) to the said steam generator (3) through the said valve means (8), and having the characteristic that a containing body (13) in fluid communication with the said second pipe (11) is fitted between the said valve means (8) and the said steam generator (3), the said containing body (13) being capable of containing the vapour phase of the said fluid, the said vapour phase being generated by the said steam generator (3).

Description

DESCRIPTION *** ** ***

Title: "Equipment for steam generation for household appliance" .

The present invention relates to apparatus for generating steam for domestic electrical appliances, hereinafter referred to for the sake of brevity as "appliances", such as steam irons, steam floor cleaners and the like. There is a known apparatus consisting of a reservoir for containing a fluid, which is connected to an electric pump, this electric pump being capable of supplying the said fluid to a steam generator. If the steam generator is of the instantaneous type, the principal drawback of the apparatus is the delay in supplying steam after the appliance has requested it. On the other hand, if the steam generator is of the storage type, in other words a steam generator having a storage steam evaporator heated by a resistive element which is controlled by thermostatic means, the principal drawback of the apparatus is the delay in supplying the steam after the appliance has requested it. This problem arises as a result of the return pressure exerted towards the water supply pump. This decreases the pump flow rate and consequently reduces the efficiency of the said apparatus . This is because, during the supply of the steam to the appliance, the fluid drawn from the reservoir by the electric pump comes into contact with the steam generator, which changes the state of the fluid from the liquid phase to the vapour phase, thus causing an increase in pressure. It is this pressure rise that creates a back pressure towards the pump, consequently detracting from its performance, especially at the initial moment of supply of the steam. In view of the prior art described above, the object of the present invention is to provide an apparatus for generating steam for domestic electrical appliances which can overcome the drawbacks of the known art . According to the present invention, this object is achieved by means of a steam generating apparatus, to be used in combination with domestic electrical appliances, as claimed in Claim 1. The present invention makes it possible to provide a steam generating apparatus which can supply good quality steam for a plurality of appliances, such as steam irons, steam floor cleaners and the like. The characteristics and advantages of the present invention will be made clear by the following detailed description of a practical embodiment, illustrated by way of example and without restrictive intent in the attached drawings, in which: - Figure 1 shows a schematic view of the apparatus according to the present invention; - Figure 2 shows a perspective view of a device of the apparatus of Figure 1. With reference to the attached figures 1 and 2, the number 1 indicates the whole of the apparatus, consisting of at least one reservoir 2 for containing a fluid, preferably but not exclusively water, at least one steam generator 3 and any domestic electrical appliance 4, which could be, for example, a steam iron, a floor cleaner, a coffee machine or a floor scrubber. The reservoir 2, which is distinct and separate from the steam generator 3 and the domestic electrical appliance 4, can be filled up when required, simply by unscrewing a filling plug or aperture 5. The reservoir 2 is in fluid connection through a first pipe 7 with pumping means 6 which can draw the water contained in the said reservoir 2 to valve means 8 through a second pipe 9. Advantageously, filter means 10 for filtering impurities out of the water contained in the reservoir 2 are housed within the said reservoir 2. It should be noted that this reservoir 2 can also be constructed without the filter means 10 while still allowing optimal operation of the apparatus 1. ' In a preferred embodiment these pumping means 6 are, for example, an electric pump, more specifically an electric vibration pump. In a preferred embodiment, this electric pump 6 comprises non-return valve means (not shown in the figures) . In a preferred embodiment, the valve means 8 are a three-way valve. The three-way valve 8 therefore receives the water contained in the reservoir 2 and drawn by the pump 10 through the pipe 9. As shown in Figure 1, this three-way valve 8 is also joined to the steam generator 3 by means of a third pipe 11. A fourth pipe 12 also runs from the three-way valve 8 and terminates in the filter means 10, or, if the said filter means 10 are not present, the said fourth pipe 12 terminates directly in the reservoir 2. With particular reference to Figure 2, it should also be noted that the three-way valve 8 incorporates a containing body 13. Preferably, this containing body 13 is shaped in the form of a cylinder; alternatively, the said containing body 13 can be shaped in the form of a parallelepiped, a cone, or other body. In a preferred embodiment, the said cylindrical containing body 13 is made in one piece with the said three-way valve 8, but in other embodiments the cylindrical containing body 13 can be separate and/or distinct from the three-way valve 8, but connected to it, by means of a threaded connection for example. It should also be noted that the cylindrical containing body -13 can be provided with a stopper 14 at its free end, in other words at the end not connected to the three-way valve 8, or at least in the part of the body which is not connected. The stopper 14 allows access to the interior of the cylindrical containing body 13, making the said cylindrical body easier to maintain and/or to clean. Clearly, the cylindrical body is hollow internally so that it can store steam during some stages of operation of the apparatus 1. In other words, the cylindrical containing body 13 acts as a buffer or reservoir for the steam which is produced by the steam generator 3. Advantageously, the cylindrical containing body or buffer 13 is made from an easily worked metallic material which has excellent characteristics for die- casting and is unaffected by corrosion phenomena caused by the presence of water vapour. An example of a material having these characteristics is brass. It should also be noted, although this is not shown in Figures 1 and 2, that the cylindrical containing body 13 can be fitted in the pipe 11 between the three-way valve 8 and the steam generator 3. In a preferred embodiment, the steam generator 3 consists of a casing or housing 15 incorporating a heating element (omitted from the figure for the sake of clarity) and a storage evaporator 16. The outlet of the casing 15 is connected to the appliance 4 by means of a fifth pipe 17 and its intake is connected to the three-way valve by means of the pipe 11. The heating element and the storage evaporator 16 are embedded in a material having high thermal conductivity, while the casing 15 is covered with an insulating material. The storage evaporator 16 preferably consists of a steam chamber of spiral or square shape. In a preferred embodiment, the steam chamber comprises the third pipe 11 and the fifth pipe 17, so that the valve means 8 and the solenoid valve 19 are directly connected to the said steam chamber. This steam chamber has a volume V_P of about ten cubic centimetres, so that the water contained in it undergoes the change of phase from liquid to vapour instantaneously, thus advantageously ensuring a rapid response whenever a supply of steam is requested by the appliance 4. A solenoid valve 19, which can be activated by an electrical push button (not shown in the figures) forming part of the appliance 4, is fitted up-line from the pipe 17 which acts as the steam outlet line. The solenoid valve 19 is positioned outside the casing 15, and allows the requested flow of steam to take place when it is activated. The mode of operation of the apparatus 1 whose construction is described above will now be explained with reference to Figure 1. When the apparatus 1 is switched on, the electric pump 6 supplies a certain quantity of water to the storage evaporator 16 through the three-way valve 8, until the maximum temperature and pressure, equal for example to T_max = 200°C and p_max = 3.5 bar respectively, are reached. As soon as the water enters the storage evaporator 16 it undergoes a change from the liquid to the vapour phase, as a result of the heating provided by the resistor. Clearly, the vapour contained in the storage evaporator 16 cannot flow out of the pipe 17 because of the presence of the solenoid valve 19. During this initial heating stage, the excess pressure developed in the storage evaporator 16 as a result of the continuous heating caused by the resistor even when the latter is not supplied with electricity (the resistor continues to heat the storage evaporator 16 even if not supplied with electricity for a certain time interval, owing to the thermal inertia of the material from which the resistor is made) , instead of being dispersed in the air or in the surrounding environment, advantageously, part of the excess steam that is produced is sent through the three-way valve 8 into the pipe 12 and from there towards the reservoir 2, or to the filter means 10 if these are provided in the reservoir, and part is stored in the cylindrical containing body 13. Advantageously, the presence of filter means 10 considerably reduces the noise caused by the steam entering the reservoir 2. The quantity of steam channelled through the pipe 12 towards the reservoir 2 or towards the filter means 10 is such that the water contained in the reservoir 2 is preheated. When the apparatus 1 is not active, in other words when no supply of steam is requested by the appliance 4, the steam in the apparatus 1 tends to become completely rarefied, thus maintaining a high pressure, and, without the cylindrical containing body 13, a subsequent request for steam would cause the electric pump 6 to start at a very low flow rate owing to the back pressure in the apparatus 1, thus evidently delaying the supply of steam when requested by the appliance 4. This is because the vibration pump 6 has a suitable electromagnetic system in which the alternating mains current and a diode produce a vibration which is used by a suitable hydraulic system to pump the water from the reservoir 2 to the storage evaporator 16. The vibration pump 6 is therefore a pumping system with a piston which has a passive intake stroke during the active electromagnetic phase and an active water expulsion stroke during the passive electromagnetic phase. The piston strokes correspond to the changes of frequency of the mains current to which the pump is connected. In particular, the vibration pump 6 has a variable flow rate which depends on the viscosity of the pumped water, the operating pressure and the temperature of the electromagnet. Consequently, in the presence of back pressure, such as that created during the period of inactivity of the apparatus 1, the efficiency of the vibration pump 6 becomes very low, thus considerably reducing the performance of the apparatus 1 in the initial instants of operation. However, because of the presence of the cylindrical containing body 13, steam is stored, making it possible to eliminate the delay in supplying steam, since the low initial flow rate of the pump 6 is supplemented by the discharge of pressure from the cylindrical containing body 13. In other words, the cylindrical containing body 13 acts exactly like a buffer which can store steam during the stages of inactivity of the apparatus 1, and can inject this steam in the initial instants following a request for steam. The quantity of steam that can be stored in the said buffer 13 must be directly proportional to the volume of the storage evaporator 16, or more specifically to the volume V_p of the steam chamber. In particular, it is possible to define a relation according to which, given the volume V_P of the steam vapour, the volume V_c of the cylindrical containing body 13 can be found. This .relation must allow for dimensional parameters and parameters of pressure and temperature to which the apparatus 1 is subject. According to the relation, the volume V_c of the cylindrical containing body 13 is in the range from 5% to 10% of the volume V_P of the steam chamber. The most advantageous relationship has been found to be one in which the volume V_c is equal to 7% of the volume V_P. Thus the cylindrical containing body 13 makes it possible for the start of the steam supply to take place in the optimal way at all times . When the cylindrical containing body 13 has been discharged during the supply of steam, the pressure in the apparatus 1 is reduced and the pump 6 has the correct flow rate, providing an optimal flow of steam to the appliance 4. The cylindrical containing body 13 completes its action shortly after the start of the request for steam by the appliance 4, and the said cylindrical containing body 13 returns to its storage function after the end of the stage in which the appliance 4 requests a supply of steam. Clearly, a person skilled in the art can, in order to meet contingent and specific requirements, make numerous modifications and variations to the enclosures described above, all such modifications and variations being contained within the scope of protection of the invention as defined in the following claims .

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Claims

CLAIMS 1. Apparatus for generating steam to be used in combination with a domestic electrical appliance (4) , comprising: a steam generator (3) ; a reservoir (2) for containing a fluid; a first pipe (7) for connecting the said reservoir (2) to pumping means (6) ; a second pipe (11) for connecting valve means (8) to the said steam generator (3) ; the said pumping means (6) being capable of supplying the said fluid contained in the said reservoir (2) to the said steam generator (3) through the said valve means (8) ; characterized in that a containing body (13) in fluid communication with the said second pipe (11) is fitted between the said valve means (8) and the said steam generator (3) , the said containing body (13) being capable of containing the vapour phase of the said fluid, the said vapour phase being generated by the said steam generator (3) .

2. Apparatus according to Claim 1, characterized in that the said steam generator comprises a storage evaporator (16) .

3. Apparatus according to Claim 2, characterized in that the said containing body (13) has a volume (Vc) directly proportional to the volume (V_P) of the said storage evaporator (16) .

4. Apparatus according to Claim 3 , characterized in that the said volume (V_c) of the said containing body (13) is in the range from 5% to 10% of the volume (V_P) of the said storage evaporator (16) .

5. Apparatus according to Claim 3, characterized in that the said volume (V_c) of the said containing body (13) is equal to 7% of the volume (V_P) of the said storage evaporator (16) .

6. Apparatus according to Claim 2, characterized in that the said storage evaporator (16) is connected to the said domestic electrical appliance (4) by a third pipe (17) .

7. Apparatus according to Claim 1, characterized in that the said containing body (13) is made in one piece with the said valve means (8) .

8. Apparatus according to Claim 1, characterized in that the said containing body (13) is connected to the said valve means (8) .

9. Apparatus according to Claim 1, characterized in that the said valve means (8) comprise first valve means and second valve means connected in series with each other.

10. Apparatus according to Claim 9, characterized in that the said first valve means are a non-return valve.

11. Apparatus according to Claim 9, characterized in that the said second valve means are a three-way valve .

12. Apparatus according to Claim 1, characterized in that the said containing body (13) is provided with a stopper (14) to provide access to the interior of the containing body (13) .

13. Apparatus according to Claim 1, characterized in that the said supply means are an electric pump.

14. Apparatus according to Claim 1, characterized in that the said containing body (13) is made from metallic material .

15. Apparatus according to Claim 14, characterized in that the said metallic material is brass .