WO2005018837A1

WO2005018837A1 - A portable sanitizer

Info

Publication number: WO2005018837A1
Application number: PCT/SG2004/000247
Authority: WO
Inventors: Kam Weng Choy; Hwai Kiang Tan
Original assignee: Technoscience Integrated Technology Appliances Pte Ltd
Priority date: 2003-08-23
Filing date: 2004-08-17
Publication date: 2005-03-03

Abstract

A steam cleaning device (10) for producing a flow of substantially dry steam for cleaning and sanitizing. The steam cleaning device (10) includes a housing contains a water reservoir (30) and a steam generator (20) of instantaneous type comprises of at least one steam channel (24) having reasonably smooth walls for containing water introduced into the steam channel (24) from the water reservoir (30). A pump is used to pump water from the water reservoir (30) into the steam generator (20). The device (10) includes heating means (26) for heating the smooth walls of the steam channel (24) to heat and vaporize water inside the steam channel (24) into the substantially dry steam by internal forced-convection boiling. Preferably, steam formed in the channel (24) may be superheated in the steam channel (24) and discharges onto a workpiece through a nozzle (40) coupled to the housing. The steam cleaning device (10) is designed to be compact for easy storage.

Description

A portable sanitizer.

Field of invention The present invention relates to cleaning devices in which a jet of dry steam is directed onto a workpiece to remove dirt and contaminants.

Background of the invention As there has been an increased interest and awareness in environmentally friendly methods for household cleaning, the interest in steam cleaning in the home has also increased. Steam cleaning has the advantage of using water rather than chemicals which are expensive and sometimes hazardous to use or dispose of. In certain steam cleaning device of the prior art the steam is generated by pumping a metered amount of water into the internal cavity of a steam generator. An embedded heater in the steam generator raises the temperature of the cavity walls and the resultant heat transfer raises the water temperature to a critical point whereby conversion or flashing of the water into steam occurs. This type of steam generator is commonly known as flash boiler or flash steam generator.

In US Pat. No 4,414,037 describes a steam cleaning system having an internally etched flash steam generator. The formation of irregular wall surfaces of the flash steam generator by etching was intended to enhance collision of the water droplets with such surfaces thereby enables the water to flash into steam. The US 4,414,037 describes such irregular wall surfaces as non-uniform internal surfaces formed by over night chemical etching, at least 8 hours. Sufficient time is required to thoroughly etch the surfaces to as deep as possible, for it is this surface which enable the water to flash into steam upon contact. The etched surfaces produces cavities that range in size from pinpoint to Vβ" diameter and depths ranging from 1/32" to shallow. The problem with the internally etched flash steam generator is the formation of the cavity wall surfaces into non-uniform surfaces is time consuming and technically demanding.

It would be an advantage for a steam cleaning device, if the design of the steam generator does not involve the impingement of water droplets against irregular cavity wall surfaces. Instead there is impingement against relatively smooth or uniform surfaces. Hence, providing much simple and faster way of constructing the steam generator. It is to this primary object that the invention is directed.

Summary of the invention The present invention solves the aforementioned problem by providing a steam cleaning device for producing a flow of substantially dry steam for cleaning and sanitizing, the device comprising of: a housing; a water reservoir contained within the housing for storing water; a steam generator of instantaneous type comprises of at least one steam channel having substantially smooth walls for containing water introduced into the steam channel from the water reservoir; heating means in the steam generator for heating the substantially smooth walls of the steam channel to heat and vaporize water inside the steam channel into the substantially dry steam by internal forced-convection boiling; and a pump for pumping water from the water reservoir into the steam generator. The steam generator adopted internal, forced-convection boiling principle or commonly referred to as two-phase flow and is characterized by rapid changes from water to vapor in the flow direction of the water through the steam channel. The vapor is superheated by forced convection from the surfaces of the steam channel to form the flow of dry steam. Hence, such steam generator does not involve the impingement of water droplets against irregular cavity wall surfaces. Instead there is impingement against relatively smooth or uniform surfaces. Therefore, providing much simple and faster way of constructing the steam generator.

According to one form of the invention, the heating means in the steam generator comprises at least one cartridge heater. According to one embodiment, the at least one steam channel of the steam generator is provided with an insert having means for deflecting and distributing water across the substantially smooth walls of the steam channel. One thus obtains a better vaporization of the water, which translates into a reduction in the expulsion of water in liquid form through the steam channel formed in the steam generator during initial heating. It is preferred that the insert is a wire coil for deflecting and distributing water across the substantially smooth walls of the steam channel. Preferably, the wire coil is in direct contact with the substantially smooth walls of the steam channel.

According to another embodiment, the at least one steam channel of the steam generator is provided with a screen disposed above at least a portion of the substantially smooth walls of the steam channel and the screen is provided with means for deflecting and distributing water above and on the substantially smooth walls. One thus obtains a better steam promotion performance.

Yet another embodiment, the steam generator is connected to a first temperature responsive means controlling the pump whereby the pump only start to pump water from the water reservoir into the steam generator when the temperature of the steam generator is at least above 100°C. This arrangement ensures that the pump is operable only when the temperature of the steam generator is good for steaming. Preferably, the first temperature responsive means is a normally open thermostat that switch on the pump when the temperature of the steam generator is in between 111°C and 119°C. According to one preferred embodiment, the steam generator is a flow through steam generator having at least one steam channel follows a straight course. Preferably, the flow through steam generator is formed by an aluminum extruded body having a cylindrical channel through its body and the channel is sealed by a first and a second coupling means. According to another embodiment, the steam generator is a flow through steam generator having at least one steam channel follows a meandering or labyrinth course. The flow through steam generator is commonly known as a flow heater.

According to one embodiment, the steam generator is connected to a second temperature responsive means controlling the heating means whereby the steam generator is prevented from overheating by cutting off electrical supply to the heating means when the temperature of the steam generator exceeded 195°C. This arrangement ensures that the steam generator does not overheat in operation. Preferably, the second temperature responsive means is a normally closed thermostat that switch off the heating means when the temperature of the steam generator is in between 195°C and 205°C.

It is preferred that a nozzle is coupled to the housing for directing the substantially dry steam to a workpiece. Preferably, the housing is provided with a base plate located at the bottom side of the housing. To cater for an event when there is a blockage along the steam flow path and the pressure built up exceeded a safety level, the device is provided with an over-pressure safety valve. It is preferred that in such event the steam is released from the over-pressure safety valve via a safety steam passage through an opening in the base plate.

Preferably, the device is provided with a thermal fuse connected in series between an input of an electrical main power supply and the heating means and the pump.

Brief description of the drawings Figure 1 is a schematic illustration of a steam cleaning device according to an embodiment of present invention; Figure 2 is a prospective view of the preferred embodiment of the steam cleaning device of figure 1; Figure 3 is a simplified circuit diagram; and Figure 4 is an exploded perspective view of the preferred embodiment of the steam cleaning device of figure 1.

Detailed description of the invention Preferred embodiments of a steam cleaning device for producing a flow of substantially dry steam for cleaning and sanitizing according to the present invention, and in particular preferred aspects and features thereof, will now be described in detail, by way of example only, with reference to the accompany drawings.

The invention will now be explained first with reference to the example shown in figure 1. A steam generator of instantaneous type 20 as shown in figure 1 is composed of a body 22, a steam channel 24 embodied in the body and a heating means 26. It is preferred that the heating means 26 is embedded in the body 22. Preferably, the heating means 26 is a cartridge heater which is embedded in the body 22. The steam channel 24 has relatively smooth or uniform surfaces/walls and irregularities are not etched or cut into the surfaces. In use, a pump 28 will pump water into the steam channel 24. The heating means 26 in the steam generator 20 will raise the temperature of the substantially smooth walls of the steam channel sufficiently to vaporize water contained inside the steam channel into reasonably dry steam by internal forced-convection boiling. Internal, forced-convection boiling or commonly referred as two-phase flow is characterized by rapid changes from water to vapor in the flow direction of the water through the steam channel. The vapor is superheated by forced convection from the surfaces of the steam channel to form the flow of dry steam. Hence, such steam generator does not involve the impingement of water droplets against irregular cavity wall surfaces.

Referring to figure 2, there is shown a preferred embodiment of the steam cleaning device indicated generally at 10 with the steam generator 20 in accordance with the basic configuration shown in figure 1 for producing a flow of substantially dry steam for cleaning and sanitizing. In a preferred embodiment, the steam cleaning device 10 has a housing 50 connected to a nozzle 40. Preferably, a handle 32 is formed in the housing with an elliptical opening 34 for comfort of handling. The steam cleaning device 10 has a water reservoir 30 with a filling opening 36. It is preferred that a baseplate 38 is fitted at the bottom side of the housing 50.

Referring back to figure 1, in one embodiment, the pump 28 is connected to the water reservoir 30, and to an electrical supply circuit with a control switch 44 which can be operated via a pushbutton 42 in the handle 32 of the steam cleaning device 10 (see figure 2). The steam generator 20 is situated downstream of the pump 28. It is preferred that an electromechanical pump is used to pump water from the water reservoir 30 into the steam channel 24 of the steam generator 20. The pump 28 is connected to the inlet coupling 47 of the steam generator 20 by a first water passage 29. If steam supply is desired, the switch 44 is energized for activating the pump 28, whereby water is pumped into the steam generator 20. In one preferred embodiment, the steam generator 20 is a flow through steam generator having at least one steam channel 24 follows a straight course. In other instance, the steam channel follows a meandering or labyrinth course. Although a single straight channel is provided in this example, it will be obvious to those skilled in the art that the invention may equally well be applied to a flow through steam generator provided with several parallel channels. The flow through steam generator is also known as a flow heater. According to one embodiment, the at least one steam channel 24 of the steam generator 20 is provided with an insert 54 having means for deflecting and distributing water across the substantially smooth walls of the steam channel 24. One thus obtains a better vaporization of the water, which translates into a reduction in the expulsion of water in liquid form through the steam channel 24 formed in the steam generator 20 during initial heating. It is preferred that the insert 54 is a wire coil for deflecting and distributing water across the substantially smooth walls of the steam channel 24. Preferably, the wire coil is in direct contact with the substantially smooth walls of the steam channel 24. The wire coil is preferably an open wire coil made of a stainless steel material or other non- corrosive material such chromium, titanium or like. Yet another embodiment, the at least one steam channel 24 of the steam generator 20 is provided with a screen (not shown) disposed above at least a portion of the substantially smooth walls of the steam channel 24 and the screen is provided with means for deflecting and distributing water above and on the substantially smooth walls. One thus obtains a better steam promotion performance. In one example, a series of opening forming a network of the screen. The electrical circuit is shown in simplified form in figure 1 and figure 3. In one embodiment, the steam generator 20 is connected to a first temperature responsive means 56 confrolling the pump 28 whereby the pump only start to pump water from the water reservoir 30 into the steam generator 30 when the temperature of the steam generator is at least above 100°C. This arrangement ensures that the pump 28 is operable only when the temperature of the steam generator 20 is good for steaming. Preferably, the first temperature responsive means 56 is a normally open thermostat that switch on the pump when the temperature of the steam generator 20 is in between 111°C and 119°C. In one example, the normally open thermostat has a closed temperature setting of about 115 ± 3.5 °C and a reset temperature setting of about 103 ± 5 °C.

In another embodiment, the steam generator 20 is connected to a second temperature responsive means 58 controlling the heating means 26 whereby the steam generator 20 is prevented from overheating by cutting off electrical supply to the heating means 26 when the temperature of the steam generator 20 exceeded 195°C. This arrangement ensures that the steam generator 20 does not overheat in operation. Preferably, the second temperature responsive means 58 is a normally closed thermostat that switch off the heating means 26 when the temperature of the steam generator 20 is in between 195°C and 205°C. In one example, the normally closed thermostat has an open temperature setting of about 200 ± 5 °C and a reset temperature setting of about 183 ± 7 °C.

Preferably, the steam cleaning device 10 is provided with a thermal fuse 60 connected in series between an input of an electrical main power supply and the heating means 26 and the pump 28. The thermal fuse 60 is connected to the steam generator 20 and it is preferred that the thermal fuse 60 has a breakdown temperature setting of about 240 °C.

Referring to figure 4, it is preferred that the steam generator 20 is a flow through steam generator that is formed by an aluminum extruded body 52 having a cylindrical channel through its body and the channel is sealed by a first coupling means 46 and a second coupling means 48. In one instance, the first coupling means 46 is an over-pressure safety valve. This ensures that in an event when there is a blockage along the steam flow path and the pressure built up exceeded a safety level, the steam is released from the over- pressure safety valve via a safety steam passage 62 through an opening in the base plate 38. The second coupling means 48 is connected to the nozzle 40 by a first steam passage

" 64. It is preferred that the nozzle 40 is coupled to the housing 50 for directing the substantially dry steam to a workpiece. The steam cleaning device 10 is designed to be compact for easy storage and being compact and small in size, the steam cleaning device 10 can be easily be stored in a small cabinet. The steam cleaning device 10 is also designed to be hghtweight, which is therefore easy to transport around. Hence, providing much greater portability and convenience. The unique characteristic of the steam cleaning device 10 adapt it for use in cleaning and sanitizing a workpiece. Being lightweight and small, the steam cleaning device 10 can be put on kitchen sink to sanitize cutlery and utensils. It is also capable of steam wash cutlery and utensils without any detergent. Grease can be removed from cutlery and utensils by high temperature steam. Other applications include sanitizing curtain, sofa, tables, chairs including clinical operating table and chair.

The examples are specific embodiments set forth herein are for illustrative purpose only and are not intended to limit the scope of present invention. Additional variation and modification with the scope of the claimed invention will be apparent to one of ordinary skill in the art in view of the teachings set forth herein.

Claims

1. A steam cleaning device for producing a flow of substantially dry steam for cleaning and sanitizing, the device comprising: a housing; a water reservoir contained within the housing for storing water; a steam generator of instantaneous type comprises of at least one steam channel having substantially smooth walls for containing water introduced into the steam channel from the water reservoir; heating means in the steam generator for heating the substantially smooth walls of the steam channel to heat and vaporize water inside the steam channel into the substantially dry steam by internal forced-convection boiling; and a pump for pumping water from the water reservoir into the steam generator.

2. The device according to claim 1, wherein the heating means comprises at least one cartridge heater.

3. The device according to claim 1, wherein the at least one steam channel is provided with an insert having means for deflecting and distributing water across the substantially smooth walls of the steam channel.

4. The device according to claim 3, wherein the insert is a wire coil for deflecting and distributing water across the substantially smooth walls of the steam channel.

5. The device according to claim 4, wherein the wire coil is in direct contact with the substantially smooth walls.

6. The device according to claim 1, wherein the at least one steam channel is provided with a screen disposed above at least a portion of the substantially smooth walls of the steam channel and the screen having means for deflecting and distributing water above and on the substantially smooth walls.

7. The device according to claim 1, wherein the steam generator is connected to a first temperature responsive means cOntiolling the pump whereby the pump only start to pump water from the water reservoir into the steam generator when the temperature of the steam generator is at least above 100°C.

8. The device according to claim 7, wherein the first temperature responsive means is a normally open thermostat that switch on the pump when the temperature of the steam generator is in between 111 °C and 119°C.

9. The device according to claim 1, wherein the steam generator is a flow through steam generator having at least one steam channel follows a straight course.

10. The device according to claim 1, wherein the steam generator is a flow through steam generator having at least one steam channel follows a meandering or labyrinth course.

11. The device according to claim 1, wherein the steam generator is connected to a second temperature responsive means confrolling the heating means whereby the steam generator is prevented from overheating by cutting off electrical supply to the heating means when the temperature of the steam generator exceeded 195°C.

12. The device according to claim 11, wherein the second temperature responsive means is a normally closed thermostat that switch off the heating means when the temperature of the steam generator is in between 195°C and 205 °C.

13. The device according to claim 1, further comprising a nozzle coupled to the housing for directing the substantially dry steam to a workpiece.

14. The device according to claim 1, wherein the housing is provided with a base plate located at the bottom side of the housing.

15. The device according to claim 14, further comprising an over-pressure safety valve wherein when there is any blockage along the steam flow path and when pressure built up exceeded a safety level, the steam is released via a safety steam passage through an opening in the base plate.

16. The device according to claim 1, further comprising a thermal fuse connected in series between an input of an electrical main power supply and the heating means and the pump.

17. The device according to claim 9, wherein the flow through steam generator is formed by an aluminum extruded body having a cylindrical channel through its body and the channel is sealed by a first and a second coupling means.