EP4532817A1

EP4532817A1 - Steam generation system comprising a small boiler making use of "instant steam technology

Info

Publication number: EP4532817A1
Application number: EP23730730.1A
Authority: EP
Inventors: Francesca Polti; Riccardo Turati; Gianpaolo ORTELLI; Alberto MORLACCHI
Original assignee: Polti SpA
Current assignee: Polti SpA
Priority date: 2022-05-27
Filing date: 2023-05-26
Publication date: 2025-04-09
Also published as: WO2023227762A1; EP4551752A1; WO2023227766A1

Abstract

The present invention is directed to a system (100) for the generation of steam in a steam apparatus, the system comprising a boiler (140), a tank (110), a feed pump (130) of water from the tank (110) to the boiler (140) by means of a first pipe (131); in which the boiler (140) has an internal volume of between 20 ml and 350 ml; the boiler (140) comprising a resistive element connected to a temperature or pressure probe present in the boiler, and is connected to a terminal (180) by a valve (170) steam supply; characterized by the fact that the boiler (140) is in fluid connection with a valve (150), which opens when the pressure in the boiler reaches a predefined value.

Description

Steam generation system comprising a small boiler making use of ’’instant steam technology”

Technical field of the invention

[0001]. The present invention is directed to a small boiler for steam generation in a discontinuous way and without delays with the so-called "instant steam technology".

State of the Art

[0002]. In recent decades there has been a growth of a variety of appliances using steam. The first domestic application of steam was the steam iron that was originally born with the so- called drop iron or traditional iron. The traditional iron features a water tank that feeds a heated chamber where water is vaporized and steam fed to the iron plate. The main advantages of this type of steam iron are the cost-effectiveness and ease of use. On the other hand, the traditional iron has a low ironing efficiency, is not suitable for difficult garments, is not able to generate continuous steam and has a significant delay in steam delivery. In addition, said steam iron, generating steam without pressure, is not suitable for vertical ironing and does not penetrate sufficiently into the tissues.

[0003]. An evolution of the traditional iron is represented by the drop iron with external tank and pump. The main difference with the traditional iron is represented by the presence of a pump that draws water from an external tank, which allows a greater autonomy of ironing, being the external tank volume considerably greater than the internal tank of the traditional iron. However, since the principle of operation is the same, this type of steam iron also presents the problem of the delay in the steam supply and the stop of the steam supply respectively when the steam supply button is pressed and released. Again, this iron, generating steam without pressure, is not suitable for vertical ironing and does not penetrate sufficiently into the tissues.

[0004]. These problems are not found in steam generator irons, where steam is generated in an external pressurized boiler and transported to the iron through a steam supply cable. Steam generator irons are very efficient but also cost more than traditional irons and tank irons. The advantages of steam generator irons compared to traditional irons and tank irons are mainly the wide and immediate availability of steam under pressure resulting in excellent penetration into the fabrics in vertical ironing. However, a disadvantage of steam generator irons is the heating time, since it is necessary to heat all the liquid in the boiler to be able to use iron. [0005]. The production of steam appliances with boilers has greatly expanded the range of equipment for domestic use, such as steam cleaners, combined suction and steam products, "garment steamers" and then steam brooms.

[0006]. All these appliances generally use steam generating boilers with a volume that preferably varies from 0.40 1 to 3.00 1, depending on the appliance. One of the problems related to the use of steam appliances is the weight and size of the boiler. In fact, a boiler that has an operating pressure of 2.5 bar must withstand a pressure of at least 12.5 bar, to avoid that a malfunction of the appliance causes a serious risk to the safety of the user. It is evident that as the volume of the boiler increases, significantly increases the size, the thickness of the wall of the boiler and with them the weight of the boiler itself to which it adds the weight of water when the boiler is full.

[0007]. However, the sizing of the boiler takes into account the need to have a certain amount of steam immediately, that is, without delays in the supply, continuously, whenever the user presses the dispensing button, and with a constant steam quality, therefore without "wet" steam delivery, as can happen if the temperature in the boiler drops. For this reason, in boilers normally used in steam appliances it is preferable never to have a volume below 0.40 1. [0008]. It would therefore be desirable to have a boiler that is smaller in size than the boilers currently used but that allows similar performance. Such a boiler would allow the production of household appliances that, while maintaining existing quality standards, would guarantee a significantly smaller weight and size of the appliance and energy savings in the heating phase.

Summary of the invention

[0009]. The present invention is directed to a system for the generation of steam in a steam appliance, the system comprising a boiler, a tank, a pump to supply water from the tank to the boiler by means of a first pipe, where the boiler has an internal volume of between 20 ml and 350 ml; the boiler comprising a resistive element connected to a temperature or pressure probe in the boiler, and is connected to a terminal by a steam supply valve; characterized by the fact that the boiler is in fluid connection with a regulation valve, which opens when the pressure in the boiler exceeds a predefined value.

Brief description of the drawings [0010]. Figure l is a schematic representation of a system according to invention.

[0011]. Figure 2 represents an exploded view of a boiler according to the invention inserted in an iron.

[0012]. Figure 3 represents a perspective view of the iron of Figure 2.

[0013]. Figure 4 represents a perspective view of the iron of Figure 2 where a section at the height of the electrovalve has been made.

[0014]. Figure 5 shows a pressure versus time graph in a boiler of an iron with a volume of 100 ml in the presence (continuous line) and in the absence (dotted line) of the regulation valve of the invention.

[0015]. Figure 6 shows pressure versus time graph of the boiler used for the graph in Figure 5 when the boiler is running but without dispensing steam.

Detailed description of the invention

[0016]. This invention is directed to a steam generation system comprising a boiler, a tank, a water supply pump from the tank to the boiler via a pipe; in which the boiler has a volume between 20 ml and 350 ml, preferably between 40 ml and 250 ml; the boiler includes a resistive element connected to a temperature or pressure probe present in the boiler and an electrovalve for dispensing steam; the boiler is also in fluid connection with a regulation valve, which opens when the pressure in the boiler exceeds a predefined value; the system preferably includes an electronic board that manages the activation of the pump at the opening of the steam valve.

[0017]. Figure 1 shows a scheme of operation of the system according to the invention. The system 100 includes a tank 110, a pump 130 that feeds the boiler 140. The water exiting the tank 110 before reaching the pump 130 is preferably filtered by the filter 120. The boiler is equipped with a heating element for water heating and steam generation, and a temperature and/or pressure regulation system (both not shown in the figure). The boiler is connected to a valve 170, preferably an electrovalve, for dispensing steam to the terminal 180 of a steam appliance, for example a steam iron, a steam broom or a steam vacuum cleaner. The opening of the (electro) valve allows the sending of steam to the terminal of the appliance that uses it, for example, in the case of an iron, the cavity generated between the body of the iron and plate, for a steam broom, the terminal of the broom, etc. In the diagram there is also a valve 150 for pressure regulation (or overpressure valve) in fluid connection with the boiler, which opens when the pressure in the boiler exceeds a set value (for example 3 bar) and closes when the pressure reaches a fixed value (for example 2.5 bar). The pressure control valve 150 is preferably, but not necessarily, connected to tank 110.

[0018]. In a preferred embodiment, on the discharge pipe 131 connecting pump 130 to boiler 140, there is a T connection 135 from which a second pipe 133 exits which connects the T- connection with the regulation valve 150. In this way, in static conditions, that is when the pump 130 is stopped and the valve 170 is closed, the regulation valve 150 is subjected to the same pressure present in the boiler 140.

[0019]. Figure 2 is an exploded view of a boiler according to the invention housed in an iron comprising a plate 10, a central body 20, and a cover 30, in which the central body 20 defines the lower part of the boiler and cover 30 defines the boiler cover. The three elements are preferably assembled together by self-forming screws 40 while the seal is preferably guaranteed by silicone sealants and adhesives suitable for working at high temperature.

[0020]. Figure 3 is a perspective view of the three elements (plate, central body and cover) mounted, in which are present the water inlet pipe 131 connected to inlet 70, the safety valve 90, and the valve 170, preferably an electrovalve.

[0021]. Figure 4 is a perspective view of the iron of figure 3, in which a vertical section with a plane perpendicular to the axis of the iron, at the height of the steam valve was made. From the section you can see how in this way of realization the second steam chamber has a top 145 defined from the top 30 lid and from the bottom plate 10. This portion of the second steam chamber allows the passage from the upper part where the first steam chamber 140 is located, to the lower part 180 bounded by the central body and the plate. However, a different way of realization is possible in which the valve 170 delivers steam directly into the second steam chamber 180.

[0022]. Figure 5 is a time (x axis) - pressure (y axis) graph. The graph was drawn using the boiler of the iron of figure 2, of about 100 ml of volume, subjected to a cycle in which for two minutes the boiler was lit without dispensing steam, and for a minute steam was dispensed continuously. The dotted line graph shows the pressure measured inside the boiler in the absence of the pressure regulation valve according to the invention. In the boiler there is a temperature regulation that causes the resistance to turn off when the set temperature is reached. However, the thermal inertia of the system causes the temperature in the boiler to rise further and the maximum pressure to reach a value in the range between 4.5 and 5.5 bar. The continuous line represents the graph time - pressure in the presence of the pressure relief valve 150. In this case, the pressure never exceeds 3 bar, since once this pressure value is reached, the valve opens and allows the liquid present in the pipe connecting the boiler 140 to the valve 150 to be discharged into the tank 110. For smaller boilers, the low thermal inertia of the system creates a strong instability of the temperature and pressure value inside the boiler as a result of the steam outputs and the consequent introduction of water into the boiler. In larger boilers, it is the volume of water that acts as a thermal flywheel, damping temperature/ pressure fluctuations in the boiler. In the normal operation of the boiler, the resistive element is switched off when the temperature/ pressure reaches the set up value. The power of the resistive element is not proportional to the volume of the boiler but to the steam flow that it is intended. Therefore, when using a boiler of reduced volume, after switching off the resistive element it is possible to have a much higher temperature increase. The presence of the regulation valve therefore allows to dampen the effect of increasing the temperature/ pressure due to the reduced size of the boiler.

[0023]. In the case of the iron of figure 2, when the user presses the steam supply button, the (electro)valve 170 is opened, and the steam passes from the boiler to the appliance terminal. As mentioned before, water is fed to the boiler through a pump 130 which, in a preferred embodiment, is activated when the valve is open. In this way, the steam output from the boiler is compensated by the water inlet. Preferably, the actuation button of the (electro)valve 170 also drives the ignition of the pump, preferably thanks to the electronic board 160.

[0024]. The water pump can be operated simultaneously by the electrovalve, or a phase shift can be introduced between the two actions. In one embodiment, the phase shift can be introduced as a delay in the activation of the pump with respect to the valve opening. In this embodiment, the pressurized steam present in the boiler passes to the terminal of the appliance and only later the water pump provides to reintegrate the steam out of the boiler with water that, once it enters the first chamber, turns into steam. The delay between actuating the water pump and actuating the electrovalve can be between 3.0 s and 0.1 s, preferably between 2.0 s and 0.2 s.

[0025]. In another embodiment, it is possible to delay the activation of the electrovalve with respect to the activation of the pump. The delay in this case cannot be very high, being perceived by the user as a delay in the steam supply. Thus, in this mode of realization, the delay is preferably between 1.0 s and 0.1 s.

[0026]. In a boiler iron, the boiler is equipped with an independent temperature/pressure regulation system and the iron is normally equipped with a resistance that serves to further overheat the steam and to heat the plate at the operating temperature of the same. Traditionally, the iron plate can be adjusted to different temperatures depending on the fabric, or you can use the iron at a fixed temperature suitable for all fabrics.

[0027]. In an iron that uses the boiler of the present invention, in addition to the pressure or temperature regulation normally present in a steam iron, there is also the circuit of the above- mentioned pressure control valve. The pressure adjustment through the control valve shall be at a value Pl higher than the setting value of the thermostat regulation T2. If Pl is too close to P2, the pressure control valve opens too often, causing hot water and steam to return to the tank too high. If on the contrary Pl is too far from P2, the overpressure valve almost never opens and the temperature in the boiler is unstable. It has been experimentally found that preferably Pl is in the range

P2+0,2 bar < Pl <P2 +1,0 bar

[0028]. Figure 5 shows a pressure vs time diagram of a steam iron according to the invention with and without pressure control valve 150, during operation applying steam supply cycles and rest cycles. Valve 170 is kept open for 1 minute and then closed for 2 minutes. It is clear that the presence of a pressure regulation valve allows the iron to work in a narrower pressure range without decreasing steam production.

[0029] Figure 6 shows the pressure vs time diagram of the same irons used for the experiment in figure 5, this time however with valve 170 always closed. In practice, the iron is lit but not used. It can be seen that the pressure varies between a maximum value of about 2 bar, to a minimum value of 1.5 bar. This corresponds to the fact that the thermostat turns off the resistance when inside the first steam chamber a temperature of about 120° C is reached, which corresponds to a pressure P2 of 2 bar. The pressure inside the first steam chamber is lowered and once reached the value of 1.5 bar the thermostat turns on the resistance that increases the vapor pressure until it reaches again at pressure P2 of 2 bar.

Claims

Claims A system (100) for the generation of steam in a steam appliance, the system comprising: a boiler (140), a tank (110), a pump (130) supplying water from the tank (110) to the boiler (140) via a first pipe (131); wherein boiler (140) has an internal volume between 20 ml and 350 ml; boiler (140) comprising a resistive element connected to a temperature or pressure probe present in the boiler, and is connected to a terminal (180) via a steam supply valve (170); characterized by the fact that boiler (140) is in fluidic communication with a regulation valve (150) that opens when the pressure reaches a prefixed value. The system according to claim 1, wherein valve (170) is an electrovalve and the system also includes an electronic board (160) that manages electrovalve (170) and pump (130). The system according to any of claims 1 or 2, wherein valve (150) is in fluidic communication with tank (110). The system according to any of claims 1 to 3, wherein the steam appliance is chosen from the list comprising a steam iron, a steam broom and a steam vacuum cleaner. The system according to any of claims 1 to 4, wherein the volume of the boiler is between 40 ml and 250 ml. The system according to any of claims 1 to 5, wherein valve (150) is set at a pressure between 2 bar and 4 bar. The system according to any of claims 1 to 6, wherein on first pipe (131) connecting pump (130) to boiler (140), there is a T-connection (135) from which a second pipe (133) exits which connects the T-connection with valve (150).