Far infrared radiation generator for use in a sauna room and a sauna room provided with the same
Filed of the invention This invention relates to a far infrared radiation generator for use in a sauna room comprising a far infrared emitting panel and a heating source, and to a sauna room provided with the generator.
Background of the invention In a conventional sauna room known as a convectional type one, there has been used a heating source such as an electric heater or fuel combustion heat radiator to produce a relatively hot (normally 80 - 110°C) and high thermal stimulant atmosphere. When exposed to such circumstance, the perspiration begins just after a certain time when capillary vessels and sudoriparous glands of skin, which had contracted by a defensive reflex action of the organism to a strong thermal stimulation, get open again with the reflex action being disappeared. Such contraction of skin entails skin drying, a blood pressure raising and breathing disorder, so that it is difficult for one to stay in the sauna room for a sufficient time to profusely perspire. Also in such sauna room, the interior of human body is heated very slowly than the skin. Consequently, the time for perspiration becomes long which means that the body is under the situation of disappearance of the defensive reflex action for a long time and accordingly the temperature of body can easily exceed 40°C, a crystal temperature for health to result in illness such as denaturalization of myocardium or lever cells. Moreover, due to the breathing disorder and blood pressure rising mentioned above, the aged, children and those suffering from high blood pressure or heart trouble cannot enjoy the convectional sauna room without any trouble. In recent years, a far infrared radiation generator has been used in a sauna because far infrared rays have high absorbability to the body and heat the body from its interior, and accordingly accelerate the perspiration. Conventional far infrared radiation generators for sauna comprise an emitting body including a ceramic substratum covered with a material capable of emitting far infrared radiation (hereinafter referred to as "far infrared-emitting material") on its top surface. The far infrared-emitting materials are typically zirconium oxide (ZrO2), titanium oxide
(TiO2), iron oxide (Fe2O3), silicon carbide (SiC), and the like. But the conventional far-infrared radiation generators have been operated at a low temperature, because they will emit far infrared rays of short wavelengths when raising its temperature higher to increase emissive power of the emitting body. The surface temperature of the conventional emitting body is, for example," 80 - 120°C, whereas sauna using such generators runs at a temperature of about 50 - 60°C (See PCT/JP94/01545 or EP0 074 748 A2). Because of the low emissive power and the relatively low room temperature, those saunas also have problems that one does not enjoy sufficient thermal feeling and stays in a sauna room for a long time. Moreover, such sauna rooms do not provide a stupe function, i.e. irradiating radiant rays to a certain part of human body. Further, the used far infrared-emitting materials are very expensive and the emitting body, especially the far infrared-emitting layer can easily be cracked by a thermal shock, even be peeled off from the substratum. And there exists other problems such as complicated configuration and high manufacturing cost of the generators. As mentioned above, all the type of conventional sauna rooms has a drawback that perspiration speed is slow and total time needed for sauna is long. In conclusion, there has not been a sauna room which not only provide a rapid perspiration and satisfactory heat feeling so that one can finish the perspiration within a maintenance period of organism's defensive reflex action to strong thermal stimulation, but also prevent breathing disorder, skin drying and blood pressure raising. Furthermore, there has not been a sauna providing a stuping effect by non-thermal stimulating and strong radiant heat.
Summary of the invention One object of the present invention is to provide a sauna room which ensures a high interior temperature and a stuping effect by irradiating powerfully a far infrared rays of wavelengths which do not give the harmful acute feeling. Another object of the invention is to provide a sauna room which ensures a high perspiration speed so that one can finish the perspiration within a maintenance period of defensive reflex action of human body. Yet another object of the invention is to provide a sauna room which ensures a satisfactory feeling of heat and relaxation and prevents blood pressure from rising, so that the aged, children and those suffering from the high blood pressure, heart trouble, etc. can enjoy the sauna room without any trouble.
Still another object of the invention is to provide far infrared radiation generator to be used in such sauna room. These and other objects of the present invention are achieved by the far infrared radiation generator according to the invention and the sauna room provided with the same. The sauna room cited throughout the description and claims should be understood to refer to any enclosed chamber to provide high temperature, such as sauna room, sauna cabin, sauna box and the like, regardless of its dimensions, configuration and accommodation capacity. The sauna room according to the present invention is provided with at least one far infrared radiation generators and thereby has an interior temperature of 80 to 110°C. The generator comprises a heating source and at least one far infrared emitting panel. The emissivity of far infrared rays radiated from the emitting panel upon heated by the heating source is above 0.5 for 9 - 20μm and less than 0.05 for below 3μm in wavelength. The emissivity herein referred to is a ratio of the radiant quality of the corresponding substance to the radiant quality of a black body under the same conditions. The heating source of the generator is prevented from being exposed to the interior of the sauna room, by the emitting panels. The heating source can be either a electric heating wire embedded in the emitting panel or a separate heat source, such as an electric heater or a fuel combustion heat radiator. One embodiment of the sauna room according to the invention is equipped with the sufficient number of far infrared radiation generators to provide the temperature of the sauna room of 80 - 110°C, each of generator comprising a far infrared emitting panel, electric heating wire embedded in the emitting panel and a thermal insulating body in the shape of box with one opened side to accept the emitting panel therein. The generators are secured to at least one side wall of the sauna room by a suitable fastening means such as latches, hooks or screws. Alternatively, trie generators can be put on the floor by means of supporting legs of the generator. In operation, the emitting panel of the generator is heated to a temperature of 200 - 350°C, preferably 250 - 300°C, by the embedded electric heating wire. Other embodiment of sauna room according to the present invention is equipped with a far infrared radiation generator with heating capacity to raise the room temperature to 80 - 110°C, the generator comprising a plurality number of far
infrared emitting panels and a separate heating source such as an electric heater or a fuel combustion heat radiator, without any embedded-type electric heating wire and thermal insulating body mentioned above relating to the former embodiment. The emitting panels cover the heating source at least to prevent it from being exposed to the inner space of the room. The generator is installed at a proper location, such as in one corner or at one side wall of the room. A far infrared radiation generator for use in a sauna room according to the present invention comprises one or more far infrared emitting panels and a heating source, wherein the emitting panel is heated by the heating source to a temperature of 200 - 350°C, preferably 250 - 300°C in operation. The emitting panel is one made by pressure molding a mixture of far infrared emitting material powder and a proper adhesive followed by heat treating, the material being any one capable of emitting far infrared rays with emissivity 0.5 or higher for 9 - 20μm and 0.05 or less for below 3μm in wavelength upon heated. One example of such emitting material is silicon dioxide, preferably crystal silicon dioxide. The silicon dioxide can be available in the form of cryolite, quartz or diatom earth, the most preferred being quartz. The adhesive can be any of well-known ones, most preferably being a water glass which does not affect the radiation spectrum of the generator adversely. According to one embodiment of the far infrared generator of the present invention, the generator comprises a far infrared emitting panel, an electric heating wire embedded therein as a heating source and a thermal insulating body in the form of box with one opened side to accept the emitting panel therein. From the central portion of a back surface of the emitting panel, extends outwardly a bolt which is fixedly secured to the panel by one end of it, especially head of it buried in the panel. The thermal insulating body is made by (1) mixing thermal insulating material powder such as white fly ash, heat and water resistant adhesive such as alumina cement and optionally asbestos or glass fibers; (2) pressure molding the mixture; and (3) calcining the molding. Optionally, the thermal insulating body can, in the middle of it have a layer in the form of net woven from asbestos or glass fibers to increase the mechanical strength of the body. Any other well known thermal insulating materials can also be used for the body. The thermal insulating body has a boring in the center portion of it, through which the bolt passes to fasten the insulating body and the emitting panel to each other in cooperation with a nut. The thermal insulating body performs the functions both of thermal and electric insulating.
Other embodiment of the far infrared radiation generator according to the present invention comprises at least one far infrared emitting panels and a separate heating source like a separate electric heater or fuel combustion heat radiator. The emitting panels are located side by side like a mosaic to surround the heating source, at least to prevent the heating source from being exposed outwardly. Surprisingly, it has been found that the sauna room according to the present invention ensures very pleasant perspiration without any feeling of skin contraction, accordingly skin drying, breathing disorder and the like which were the problems relating to the conventional air-convectional type saunas. Furthermore, the blood pressure have not been raised, rather lowered with improving the operation of heart in the sauna room of the present invention, so that it is specially effective for the hypertrophy and disorders of circulation system including high blood pressure and can be enjoyed by everyone including the aged and children without feeling any inconvenience. In particular, since the far infrared radiation generator of the present invention irradiates far infrared rays powerfully without giving any acute feeling, the sauna room of the invention provides the effect of stupe treatment as well.
Brief description of the drawings Fig. 1 is a schematic perspective view of one embodiment of far infrared radiation generator according to the invention; Fig. 2 is a cross sectional view of the far infrared radiation generator shown in
Fig. 1; Fig. 3 is a schematic top plan view of one embodiment of a sauna room according to the, invention equipped with the far infrared radiation generators shown in Figs 1 and 2; Fig. 4 is a schematic perspective view of the sauna room shown in Fig. 3; Fig. 5 is a schematic perspective view of another embodiment of the far infrared radiation generator according to the invention; Fig. 6 is a schematic perspective view of still another embodiment of the far infrared radiation generator according to the invention; Fig 7 is a is a schematic perspective view of yet another embodiment of the far infrared radiation generator according to the invention which is portable and has supporting legs;
Fig. 8 is a schematic perspective view of another embodiment of a sauna room according to the invention provided with the far infrared radiation generators shown in Fig. 7; Fig. 9 is a schematic cross sectional enlarged view of a portion of surface of emitting panel of the far infrared radiation generator according to the invention; and Fig. 10 is a graph showing the emissivity of far infrared radiation of the far infrared radiation generator according to the invention.
Detailed description of the preferred embodiments Hereinafter the invention will be described in more detail with referring to the appended drawings. Throughout the specification, same or similar parts are denoted with same reference numeral. Fig. 1 shows a perspective view of one embodiment of a far-infrared radiation generator according to the invention and Fig. 2 is a cross sectional view of the generator taken along the line A - A in the Fig. 1. The generator 1 comprises a far infrared emitting panel 2 having an electric heating wire 3 embedded therein and a thermal insulating body 4 in the form of box with one opened side adapted to receive the emitting panel 3 in it. The electric heating wire 3 is preferably biased towards an emitting surface 5 of the emitting panel 2 as shown in the Fig 2. Such configuration is beneficial because it reduces the variation in temperature, accordingly temperature strain between the emitting surface 5 and a back surface 6 of the emitting panel 2, prevent the cracking of the emitting panel 2 and increase the thermal efficiency of the generator 1. Two ends of the electric heating wire 3 are connected through leads, not shown, to an electric power source, not shown, to have a supply of a current therefrom. The electric heating wire 3 is selected among a nichrome wire, tantalum wire and manganese wire, preferably nichrome wire. The generator 1 is provided with a thermostat, not shown, by which the temperature of the far infrared emitting surface 5 is controlled to be in the range of 250 - 300°C. The emitting panel 2 is made by mixing a silicon dioxide containing powder and water glass as a adhesive agent and pressure molding the mixture followed by heating treatment. The silicon dioxide containing powder is selected among cryolite powder, quartz powder and diatomite powder, and preferably is a quartz powder. The thermal insulating body 4 is also made by mixing white fly ash, alumina cement as an adhesive and optionally asbestos or glass fibers, pressure molding the mixture and
calcining the molding. Additionally, a net woven from asbestos or glass fibers can be laid in the middle of the thermal insulating body 4 to increase the strength of it. It is also possible to use any other well-known adhesives with good heatproof, waterproof and/or electric insulating features. From the central portion of the back surface 6 of the emitting panel 2 extends outwardly a bolt 7 which is fixedly secured to the emitting panel 2 by its one end, preferably a head 8 buried in the panel 2, and in turn passes through a boring 9 formed in the thermal insulating body 4 to be engaged with a nut 10 on a back surface of the thermal insulating body 4, thereby fasten the emitting panel 2 and the insulating body 4 to each other. To improve the thermal insulating feature of the body 4, there is inserted a spacing means 14 between the emitting panel 2 and the insulating body 4 to form a space 15 between them. The space 15 can optionally be filled with asbestos or the like. Further, it is possible to mount a reflection plate such as aluminum plate, not shown, on the back surface 6 of the emitting panel 2 to improve the radiation efficiency. Around the periphery of the insulating body '4 is mounted a frame 11 which has a proper means to secure the generator 1 to a wall of a sauna room such as hooking means and/or a detachable supporting legs to put the generator on the floor, all of them not shown. Fig. 8 shows the far infrared radiation feature of the generator 1 in operation. As can be seen, the generator 1 irradiates far infrared rays at an emissivity of 0.5 or higher for 9 - 20μm and 0.05 or less for below 3μm. Figs. 3 and 4 show one embodiment of a sauna room 20 of the present invention for a public use equipped with the far infrared radiation generators 1 shown in Figs. 1 and 2. The sauna room 20 has four side walls 21, 22, 23, and 24, a door 25 formed in one side wall 21, bench 29 having lower step 26 and upper step 27 and floor 28, wherein each of the side walls are of boarded doubly. Each of the walls has rectangular recesses 30 adapted to receive the generator 1. Each of the generators 1 is secured to the walls by suitable fastening means such as hooking means or screw. Each of the recesses 30 is dimensioned to leave intervals between four sides of the recess 30 and corresponding ones of the generator 1, for example 3 cm for lateral and base sides and 7 - 8cm for upper side. Likewise, the recess 30 is so deep that a front surface of the generator 1 is positioned rearward than the wall surface, for example as much as about 5 - 7cm. A suitable protecting means such as a wooden lattice or grid is mounted in front of the generator 1 to prevent the human body from contacting the
surface of the generator 1 as well as protect the generator 1 from damage. It is preferred that the generators 1 are installed not higher than the level of shoulder of human body and the upper step 27 of the bench 29 is somewhat wide, for example as much as 50 - 70cm, to enable a person adjusting the distance from the generator 1. When power is supplied to the generators 1, they irradiate far infrared rays. The temperature of the sauna room is maintained to be at 80 - 110°C by way of a thermostat, not shown, controlling the amount of electric current supplied to the generators or turning off the electricity to some of generators 1. It would be obvious that the number of steps of the bench 29 can be varied depending on the demands for the sauna room such as accommodation ability. Likewise, the generators 1 may be installed three or less walls, rather than all the walls, provided that the temperature of the sauna room is ensured to be at 80 - 110°C. Referring to Figs. 5 and 6, they show another embodiments of the far infrared radiation generator of the invention, respectively. The generator 1 comprises at least one far infrared emitting panel 2 and a separate heating source such as a separate electric heater or a fuel combustion heat radiator. It is differed from the embodiment shown in Figs. 1 and 2 by no provision of the embedded type electric heating wire and the thermal insulating panel. The emitting panels 2 are fixed by a suitable fastening means such as a bolt 7 and a nut 10 (see Fig. 2) side by side to each other like a mosaic to a hexahedral or cylindrical framework, not shown, in conformity with the outline of the heating source, as shown. It is preferred to arrange the emitting plates 2 on the sides where the heating source is exposed outwardly. Another embodiment of a far infrared radiation generator 1 of the invention shown in Fig. 7 is substantially same as the generator 1 shown in Fig. 2 except that it is further provided with detachable supporting legs 71 on the under side of the generator 1, by which the generator 1 can be put on the floor. In addition, the generator 1 can be provided with a handle, not shown, on the upper side of the generator 1, by which one can carry the generator 1 with him to a desired location. Fig. 8 shows another embodiment of a sauna room 81 of the present invention for a private use having far infrared radiation generators 1 shown in Fig. 7. In the embodiment, the generators 1 are preferably located in front of and at the back of person 82 to be irradiated.
The emitting surface 5 of the emitting panel 2 is preferably a rough surface having a lot of protrusions 91 to increase radiating surface area of it. Fig. 9 shows some variations of the rough surfaces 5. As can be seen, the surface 5 may be in the form of wave, zigzag, stair-likely tapered or combinations thereof in the cross sectional view. While this invention has been described with respect to its presently preferred embodiments, other modifications and variations will occur to those skilled in this art. For example, the emitting panel can be of circle, oval, triangle, polygon and the like. Such modifications and variations, however, are intended to fall within the scope of the appended claims.