Steam Generator

FIELD OF INVENTION:

This invention relates to a steam generator, more particularly to a steam generator used for steaming systems, steam irons and ironing systems.

BACKGROUND OF THE INVENTION:

Steam is produced in a steam generator and is delivered to a downstream system through a hose. The hose is connected to a steam outlet of the steam generator through a valve. The steam generator is typically filled with tap water which normally contains various gases as well as salts. Salts which are customarily found in tap water include sodium bicarbonate, sodium sulfate and magnesium bicarbonate. The percentage of sodium and magnesium salts determines the hardness of water. The heating of water entails decomposition of water into its constituents, and such constituents, especially carbonates, deposit on the adjacent surfaces in the form of scale. Scale is an insulator of heat and hence the energy requirements of the steam generator increase as the thickness of the scale increases. A filter is placed in the valve to prevent the solid impurities such as scale particles passing to the downstream system from the steam generator. However, over time the solid impurities tend to build up around the filter and clog it. This clogging increases the pressure drop across the valve and reduces the steam rate. This can lead to failure of the valve in case the filter is completely blocked. Furthermore, it is not possible to clean the filter since the valve is not opened during the service life of the steam generator.

EP 658647 discloses a steam generator for flat irons comprising a water reservoir having in its upper part a steam outlet aperture intended to be connected to the flat iron and an aperture for filling the reservoir with water. The generator comprises, above the aperture of the outlet, a filter intended to hold back the particles of tartar formed during heating of the water and capable of being carried along by the steam towards the aperture of the steam outlet. The filter is placed in the filling opening of the water reservoir, under the stopper which closes this opening. However, this system is not configured to minimize scale formation. Further, in such systems the filter may be removed each time the steam generator is refilled. Moreover, the steam generator cannot

be refilled while in operation, as the steam generator then is at a pressure above atmospheric pressure.

Therefore, it is an object of the invention to provide a steam generator which does not have the disadvantages of the known steam generator described before, in particular to provide a steam generator which endows a user with the ease of generating quality steam.

This object is achieved by features of the independent claim. Further developments and preferred embodiments of the invention are outlined in the dependent claims.

SUMMARY OF THE INVENTION:

In accordance with the invention, a steam generator comprises a steam generator housing. At least one removable filter is disposed in the steam generator housing for filtering solid particles from steam. The steam generator is provided with a compartment for accommodating a water treatment feature, the compartment being coupled to the filter. Steam generators are typically filled with tap water. Minerals present in potable natural and city water cause scale formation in the steam generator. Scale formation reduces heat transfer, thereby substantially reducing the capacity of the steam generator to generate steam and vastly increasing the energy required to operate the steam generator because of such poor heat transfer. The water treatment feature provided in the compartment minimizes scale formation, thereby improving the efficiency of the steam generator. The water treatment feature either reacts to the alkalinity of the water in the steam generator, neutralizes the hardness of the water or it modifies the surface tension of the water, removes foam and prevents the carry-over of fine water particles into the steam. The quality of the steam is further ensured by allowing the steam to pass through the removable filter. Solid impurities, if any, present in the steam are retained by the filter. This further prevents the scale particles from being carried away along with the steam. Since the filter is removable, it can be inspected for blockage by solid impurities occasionally. Also, as the compartment for accommodating the water feature is coupled to the filter, it can be removed along with the filter for inspecting the condition of the water conditioner. According to another embodiment of the invention, the compartment is fixedly coupled to the filter. The compartment is placed below the filter. The position of the compartment ensures that the water treatment feature always is in contact with the water in the steam generator even when the water level is at its lowest.

According to another embodiment of the invention, the compartment is coupled to the filter via a flexible filament or a flexible rod. The flexible filament or the flexible rod allows the position of the compartment to be variable within the steam generator. In other words, the flexible filament or the flexible rod allows the compartment to float on the water, which ensures good contact between the water treatment feature and the water in the steam generator. The flexible filament or the flexible rod is made of any polymeric material which is capable of withstanding high temperatures.

According to an embodiment of the invention, the water treatment feature includes a water conditioner in the form of a pill or a gel. The hardness of the water used in the steam generator has a great influence upon the useful life. By means of the water conditioner, the tap water is softened so that the deposition of scale during operation of the steam generator is substantially reduced. The water conditioner also modifies the surface tension of the water and prevents the carry-over of fine water particles into the steam. The reaction between the water conditioner and the water in the steam generator takes place when the pill melts or as a result of a capillary action.

According to another embodiment of the invention, the water treatment feature comprises a soft sponge impregnated with a water conditioner. The porous nature of the sponge ensures good contact between the water conditioner and the water in the steam generator. According to another embodiment of the invention, the water conditioner is an anti-scaling agent or an anti- foaming agent. The anti-scaling agent reacts with the alkalinity of the water in the steam generator and neutralizes the hardness of water. The anti- foaming agent is a mixture of surface-active agents for modifying the surface tension of water, removing foam and preventing the carry-over of fine water particles into the steam. The terms "anti-scaling or anti- foaming" are intended to embrace all types of substances which are used to soften water by removing scale-forming calcium and/or magnesium ions from hard water or replacing them by the more soluble ions, such as sodium ions, and which are used to modify the surface tension of water.

According to another embodiment of the invention, the steam generator housing comprises a rinsing opening which is closeable by a removable cap. A user of the steam generator is expected to perform a self-clean action in order to remove the deposited scale from the walls of the steam generator. A rinse indicator may be provided either on the steam generator housing or on a downstream system, which indicator utilizes the steam generated by the steam generator to warn the user that the amount of scale has reached a

certain limit and that the steam generator has to be cleaned. The length of intervals between successive rinsings depends upon the quality of the water used to generate steam, the number of hours the steam generator is in operation and so on. The user rinses the steam generator and pours out the water through the rinsing opening by removing the cap. According to another embodiment of the invention, the removable cap is coupled to the filter and the compartment. The filter and the compartment are removed for inspecting their condition by removing the cap. The filter is placed in the valve to prevent that the scale particles are passed to a downstream system from the steam generator. This further prevents the scale particles from tanning the garment if the downstream system is a soleplate of an iron. However, over time the solid impurities tend to build up around the filter and clog it. This clogging increases the pressure drop across the valve and reduces the steam rate. This can lead to failure of the valve in case the filter is completely blocked. When tap water is heated to temperatures above 68 ⁰ C, scale formation is inevitable. In the long run the thickness of the scale causes overheating and reduces the efficiency of the steam generator. During a rinse cycle, the user can inspect the filter and can clean or replace the filter depending on the condition of the filter. Furthermore, it is not possible to provide the steam generator with a quantity of water conditioner which is sufficient to soften the water used during the entire life of the steam generator. The water conditioner must be replaced by a fresh water conditioner after it has been used for a number of hours. The removable cap enables replacement of the water conditioner during the rinse cycle.

According to another embodiment of the invention, the filter is disposed in a filter housing having a steam inlet and a steam outlet, and the steam inlet and the rinsing opening are situated on opposite end portions of the filter housing and the steam outlet is situated between the steam inlet and the rinsing opening and is oriented in a transverse direction relative to the steam inlet and the rinsing opening. This configuration results in ease of manufacturing of the steam generator. The steam generator housing has only one opening to accommodate the rinsing opening to which the filter and the compartment are coupled.

According to yet another embodiment of the invention, the filter is disposed in a filter housing having steam inlets and a steam outlet, and the rinsing opening and the steam outlet are situated on opposite end portions of the filter housing. The steam enters the filter housing through the pores comprised in the filter housing. The pores act as steam inlets. Since the steam outlet and the rinsing opening are situated on opposite end portions of the filter housing, rinsing out water does not interfere with the output of steam. In this manner,

accidental blockage of the steam outlet with solid particles during the rinse cycle is precluded.

According to another embodiment of the invention, the rinsing opening is situated in a bottom portion of the steam generator housing and the steam outlet opening is situated in a top portion of the steam generator housing. It is easy to drain the water if the rinsing opening is at the bottom of the steam generator housing. Rinse water can flow out under the action of gravity once the cap is removed. Similarly, it is convenient to have the steam outlet in the top, as the steam rises vertically and exits through the steam outlet.

According to another embodiment of the invention, a steaming system comprises the steam generator described above. The steaming system uses the steam generated by the steam generator for various applications. The configuration of the steam generator as described above ensures the quality of the steam generated.

According to another embodiment of the invention, an iron comprises the steam generator described above. The configuration of the steam generator described above prevents the tanning of a garment to be ironed.

BRIEF DESCRIPTION OF DRAWINGS:

Figure 1 shows a steam generator according to one embodiment of the invention Figure 2 shows a steam generator according to another embodiment of the invention

DETAILED DESCRIPTION:

The present invention will be described with respect to particular embodiments and with reference to certain drawings, but the invention is not limited thereto. Any reference signs in the claims shall not be construed as limiting the scope. The drawings described are schematic and non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes. The term "comprising" as used in the present description and claims, does not exclude other elements or steps. Where an indefinite or definite article is used when referring to a singular noun e.g. "a" or "an", "the", this includes a plural of that noun unless something else is specifically stated.

Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used

are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than those described or illustrated herein.

Moreover, the terms top, bottom, over, under and the like in the description and the claims are used for descriptive purposes and not necessarily for describing relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other orientations than described or illustrated herein.

As shown in Figure 1, a steam generator 1 is fitted with an electrical heater 2. The steam generator 1 includes a steam generator housing 15. The steam generator housing 15 comprises a rinsing opening 8 for rinsing out water. The rinsing opening 8 is closeable by a removable cap 9. The removable cap 9 comprises a threaded nozzle which is screwed into the opening 8. A filter housing 20 comprises a steam inlet 6 and a stem outlet 10. A filter 7 is disposed in the filter housing 20. A valve 11 is coupled to the filter housing 20 via the steam outlet 10. The steam outlet 10 is connected to a downstream system (not shown) via a rubber hose 12. Water is fed to the steam generator 1 through a water inlet 13. Another rubber hose 14 connects the water inlet 13 to a water supply (not shown). A compartment 4 for accommodating a water conditioner 3 is coupled to the filter 7. The compartment 4 is coupled to the filter 7 by means of a flexible filament or a flexible rod 5. The steam generator 1 is filled with water through the water inlet 13. When the steam generator 1 is provided with a dedicated water inlet 13, it can be refilled even during operation. Such a steam generator is known as an unlimited steam generator. The water used in the steam generator is typically tap water. Since tap water contains inorganic substances such as calcium and sodium, they remain within the steam generator 1 as scale particles after the water is converted to steam. By means of the water conditioner 3, the tap water is softened so that the deposition of scale during operation of the steam generator 1 is substantially reduced. The compartment 4 coupled to the filter 7 accommodates the water conditioner 3. The compartment 4 is coupled to the filter 7 by means of the flexible filament or the flexible rod 5. The flexible filament or the flexible rod 5 is either screwed or plugged into the removable cap 9. The flexible filament or the flexible rod 5 allows the the position of the compartment 4 to be variable within the steam generator 1. In other words, it allows the compartment 4 to float on the water in the steam generator 1. The flexible filament or the flexible rod 5 is made of any polymeric material which is capable of withstanding high temperatures. The compartment 4 has a perforated surface, which allows the water to come

into contact with the water conditioner 3. The water conditioner is in the form of a pill or a gel. A soft sponge impregnated with a water conditioner can also be placed in the compartment 4. As the conditioner comes into contact with water, the chemical reaction takes place and softening or de- foaming of water occurs. This happens as the pill melts in the water or as a result of a capillary action. The porous nature of the sponge further ensures good contact between the water conditioner 3 and the water in the steam generator 1. The water conditioner 3 can be an anti-scaling agent or an anti- foaming agent or a combination of both. Anti-scaling agents react with the alkalinity of the water in the steam generator 1 and neutralize the hardness of the water. Anti- foaming agents are a mixture of surface active agents that modify the surface tension of water, remove foam and prevent the carry-over of fine water particles into the steam. The water is heated by means of the electrical heater 2. The steam thus generated passes through the filter 7 and exits the steam outlet 10. The flow of steam through the steam outlet 10 is controlled by the valve 11 which is an electromechanical actuating valve. The filter 7 is meant to hold back the scale particles formed during heating of the water. It ensures that clean steam is passed to the downstream system. The filter 7 is made of a thin- walled mesh which is a lattice work or a perforated sheet, made preferably of stainless steel or plastic material. The filter 7 is attached to the removable cap 9 either by screwing or as a tight plug-in.

It is not possible to provide the steam generator 1 with a quantity of conditioner 3 which is sufficient to soften the water used during the entire life of the steam generator. The water conditioner 3 must be replaced by a fresh water conditioner after it has been used for a number of hours. The removable cap 9 enables replacement of the water conditioner 3 during the rinse cycle. Further, over time the scale particles tend to build up around the filter 7and clog it. This clogging increases the pressure drop across the valve 11 and reduces the steam rate. This can lead to failure of the valve 11 in case the filter 7 is completely blocked. A user is expected to perform a self-clean action in order to remove the deposited scale from the walls of the steam generator 1. A rinse indicator may be provided either on the steam generator 1 or on the downstream system to warn the user that the amount of scale has reached a certain limit and that the steam generator 1 has to be cleaned. The length of the intervals between successive rinsings depends upon the quality of the water used to generate steam, the number of hours the steam generator 1 is in operation and so on. The user rinses the steam generator 1 and pours out the water through the opening 8 and fills the steam generator 1 with fresh water. During this period, the user can also check the filter 7 and can clean or replace the filter depending on the condition of the filter. Since the filter is

situated in the outlet for rinsing, the filter is checked occasionally i.e., only during the rinse cycle. Similarly, during the same rinse cycle, the user can also replace the water conditioner 3. Solid arrows represent the flow of water whereas the dashed arrows represent the flow of steam. The steam generator shown in Figure 2 is similar to that shown in Figure 1 but has a different configuration. The steam generator 1 is fitted with an electrical heater 2. The steam generator 1 includes a steam generator housing 15. The steam generator housing 15 comprises a rinsing opening 8 for rinsing out water. The rinsing opening 8 is closeable by a removable cap 9. The removable cap 9 comprises a threaded nozzle which is screwed into the opening 8. A filter housing 20 comprises steam inlets denoted by the numeral 6 and a steam outlet 10. A filter 7 is disposed in the filter housing 20. A valve 11 is coupled to the filter housing 20 via the steam outlet 10. The steam outlet 10 is connected to a downstream system (not shown) via a rubber hose 12. Water is fed to the steam generator 1 through a water inlet 13. Another rubber hose 14 connects the water inlet 13 to a water supply (not shown). A compartment 4 for accommodating a water conditioner 3 is fixedly coupled to the filter 7.

The filter housing 20 is arranged vertically in such a manner that one end of the filter housing 20 comes into contact with the bottom of the steam generator housing 15 and the other end comes into contact with the top of the steam generator housing 15. The removable cap 9 is placed at the bottom of the steam generator housing 15, whereas the valve 11 is placed on top of the steam generator housing 15. The removable cap 9 and the valve 11 communicate with the steam generator 1 through the filter housing 20, which is in the form of a nozzle. The filter housing 20 is either welded or embossed onto the steam generator 1. It has a perforated surface which allows steam to pass through the perforations. These perforations act as steam inlets 6. The steam then passes through the filter to the steam outlet 10. The compartment 4 is placed below the filter 7 and anchored to the removable cap 9. The water conditioner 3 in the compartment 4 is placed in such a way that it always comes into contact with the water in the steam generator 1 even when the water level is at its lowest. The filter 7 is anchored firmly to the removable cap 9. The filter housing 20 is locked into the steam outlet 10, which protrudes into the steam generator 1. When the water level in the steam generator 1 is at its maximum, the filter 7 will be partially covered by water, allowing the generated steam to escape through the filter on the uncovered side towards the steam outlet 10. The steam then will be directed to the rubber hose 12 and to the downstream system via the valve 11. During the rinsing process, the filter 7 and the compartment 4 are detachable

It is to be understood that although preferred embodiments, specific constructions and configurations, as well as materials, have been discussed herein for devices according to the present invention, various changes or modifications in form and detail may be made without departing from the scope and spirit of this invention.