JP2003204886A - Electric water boiler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem of an electric water boiler, where glass wool is used or a container or bag stuffed with a powdery heat insulating material is used, that the heat insulation performance is deteriorated and the power necessary for the heat retaining of the electric water boiler is large because a joint is formed between the heat insulating materials and the heat escapes from the joint. <P>SOLUTION: The heat insulating material is solidified by using a binder without deteriorating the heat insulating performance, and the coefficient of heat conductivity of the heat insulating material is the same as or lower than that of stationary air after the solidification. In the electric water boiler, a water reserving container is covered with the heat insulating material with the high heat insulation performance and has no joint, so that the heat will not escape from the joint and only a small quantity of electric power is required for the heat retaining to achieve the energy saving electric water boiler. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric water heater for keeping and supplying hot water for drinking at home or office.

[0002]

2. Description of the Related Art An electric water heater puts water in it and connects it to a power source to boil the water, but it is necessary to keep the hot water at a substantially constant temperature for a long time. Therefore, in general, various heat insulating materials are provided around the water storage container in the electric water heater.
Examples of the heat insulating material include glass wool having a thermal conductivity of about 35 mW / m · K and a vacuum heat insulating material having a thermal conductivity of about 7 mW / m · K. In addition, there is also a metal reflector insulating material that insulates by reflecting infrared rays at high temperatures.

However, the glass wool or metal reflector heat insulating material has a problem that the heat insulating performance is low, and the vacuum heat insulating material has a problem that the heat insulating performance deteriorates when processed into a complicated shape. Further, it is difficult to uniformly cover the water storage container with these heat insulating materials, and as shown in FIG.
A seam occurs between the two. Since the heat leaks from this joint, there is also a problem that the heat insulation performance is deteriorated.

In order to solve these problems, 18 mW /
There is a method of solidifying and using an inorganic powdery heat insulating material called xerogel of about m · K. As a conventional method for solidifying a powdery heat insulating material, for example, Japanese Laid-Open Patent Publication No. 10-5080.
There was one as described in Japanese Patent Publication No. 49. According to this, airgel (including xerogel) which is a powdery heat insulating material is solidified by using an aqueous binder dispersion solution such as an organic polymer or an inorganic binder, and the solid content is 32 to 46 m.
We have realized a solidified heat insulating material with a thermal conductivity of about W / mK.

[0005]

However, the method used in the above prior art has a problem that the heat insulating performance after solidification of the powdery heat insulating material is about the same as that of glass wool, and the heat insulating performance is low. In addition, when glass wool is used or when the powdered heat insulating material is packed in a container, a bag, or the like, a seam between the heat insulating materials occurs, and heat leaks from this seam, which deteriorates the heat insulating performance. Also had.

[0006] The present invention is to solve the above-mentioned prior art, and hardly deteriorates the heat insulating performance of the heat insulating material.
An object of the present invention is to provide an energy-saving electric water heater that can reduce electric power for heat retention (hereinafter referred to as heat insulation power) by solidifying a heat insulating material with a thermal conductivity equal to or lower than that of stationary air and closely adhering to a water storage container. And

[0007]

In order to solve the above-mentioned conventional problems, an electric water heater according to the present invention is a heat insulating material in which elemental heat insulating materials are combined with a binder and the heat conductivity is equal to or lower than that of stationary air. The water storage container is seamlessly covered with, and the water storage container is covered with a highly heat-insulating insulating material whose thermal conductivity is less than that of still air, and since there is no seam, heat leaks from the seam. Without, it is possible to realize an energy-saving electric water heater with low heat insulation power.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention comprises a heat insulating material having a thermal conductivity lower than or equal to that of stationary air, which is obtained by combining elementary heat insulating materials with a binder. Is a seamless cover of the water storage container, the thermal conductivity is less than the thermal conductivity of the still air to cover the water storage container with a high heat insulating material, because there is no seam, heat from the seam It is possible to realize an energy-saving electric water heater with low heat insulation power without leaking.

The invention according to claim 2 is the electric water heater according to claim 1 in which the heat insulating material and the water storage container are connected by a binder, and the thermal conductivity is equal to or lower than the thermal conductivity of still air. Since the adhesion between a certain highly heat-insulating material and the water storage container can be improved and integrated with the water storage container, an energy-saving electric water heater with low heat-retention power can be realized.

The invention according to claim 3 is the electric water heater according to claim 1 or 2, wherein the elementary heat insulating material is hydrophobic and has a porous body, and the binder is a water-soluble organic binder. Since the water storage container can be seamlessly covered with a high heat insulating material whose thermal conductivity is less than that of still air and can be integrated with the water storage container, it is possible to realize an energy-saving electric water heater with low heat insulation power.

Further, according to the invention of claim 4, the water storage container, the heater for heating the water in the water storage container, the hot water outlet passage for letting out the water, and the thermal conductivity of the air whose thermal conductivity is stationary. Having a heat insulating material which is the following, water is added to a mixture of a hydrophobic and fine pore heat insulating material and a water-soluble organic binder, and the mixture is kneaded and then applied to the water storage container to remove the water. By doing so, it is an electric water heater equipped with the above-mentioned heat insulating material, and the water storage container can be seamlessly covered with a high heat insulating heat insulating material whose thermal conductivity is equal to or lower than that of still air, and can be integrated with the water storage container. Therefore, it is possible to realize an energy-saving electric water heater with low heat insulation power.

Further, the invention according to claim 5 is that a water storage container, a heater for heating the water in the water storage container, a hot water outlet passage for letting out the water, and a thermal conductivity of air whose thermal conductivity is stationary. Having an insulating material which is the following, in an electric water heater equipped with the insulating material as a molded body that adheres to the water storage container by applying pressure and temperature to a mixture of the elementary insulating material and the resin binder, Since the water storage container can be seamlessly covered with a highly heat-insulating insulating material having a thermal conductivity equal to or lower than the thermal conductivity of still air, an energy-saving electric water heater with low heat-retention power can be realized.

Further, the invention according to claim 6 is the electric water heater according to any one of claims 1 to 5, wherein the elementary heat insulating material is silica xerogel. The silica xerogel is extremely high among non-vacuum heat insulating materials. Since it has high heat insulation performance, it can realize an energy-saving electric water heater with low heat insulation power.

Further, the invention according to claim 7 is the electric water heater according to any one of claims 1 to 6, which has a raw heat insulating material or binder and a fibrous substance that binds or is entangled with each other. It is possible to improve the strength of the heat insulating material without deteriorating the heat resistance, and to realize an energy-saving electric water heater with a small amount of heat insulating power that can withstand practical use.

The invention according to claim 8 is the electric water heater according to any one of claims 1 to 7, which contains at least one of a substance that reflects and absorbs infrared rays, Since the temperature dependence of the heat insulating property of the heat insulating material is reduced, and the heat insulating material having high heat insulating performance even at high temperature can be realized, it is possible to realize an energy-saving electric water heater with low heat insulating power.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes a main body of an electric water heater main body (hereinafter, referred to as a main body in this embodiment).
Then, the water storage container 2 having an inner diameter of 184 mm and a depth of 200 mm (hereinafter, referred to as a container 2 in the present embodiment) for storing water therein is provided. Reference numeral 3 is an inner plug adapted to seal the mouth of the container 2. Reference numeral 4 is an upper lid that covers the upper portion of the main body 1 so as to be openable and closable. Reference numeral 5 is a vapor passage provided in the upper lid, one end of which penetrates the inside plug 3 to communicate with the inside of the container 2 and the other end of which communicates with the atmosphere. A water leakage prevention valve 6 is arranged in the steam passage 5 and shuts off the steam passage 5 when the vehicle falls over. Here, the steam passage 5 is complicatedly bent. As a result, when the pressure inside the container 2 becomes higher than the atmospheric pressure such as when the water in the container 2 boils, steam is discharged to the outside of the main body through the steam passage 5.
It is configured so that the outside air and the air between the water surface in the container 2 and the upper lid 4 (hereinafter referred to as inside air in this embodiment) are not easily mixed.

Reference numeral 7 is a motor provided at the bottom between the main body 1 and the container 2, 8 is a pump driven by the motor 7, and its suction port 9 communicates with the bottom of the container 2. A discharge port 10 of the pump 8 communicates with the hot water outlet pipe 11. 12
Is a tap, from which the hot water is poured out of the electric kettle. Therefore, the hot water outlet path is from the container 2 to the suction port 9,
Passing through the pump 8, the discharge port 10 of the pump 8 and the hot water outlet pipe 11,
It becomes the outlet 12.

Reference numeral 13 denotes a heater for heating, which has a doughnut-shaped central portion and is attached to the lower portion of the container 2. Reference numeral 15 is a start switch for driving the motor 7, which has a variable resistor, and is operated via a rod 17 by a push operation switch of a push button 16.

Reference numeral 18 denotes a compression type spring, which constantly urges the rod 17 to be pushed upward. Reference numeral 19 is a control device, which takes in a signal from the temperature detector 14 and controls the heater 13 and the like.
Reference numeral 20 denotes a heat insulating material that covers the side surface of the container 2, and plays a role of suppressing the heat of the container 2 from escaping from the side surface and the bottom surface of the main body 1.

In this embodiment, as the heat insulating material 20, silica xerogel (hereinafter referred to as xerogel in this embodiment) solidified with a binder was used. This is equivalent to a plain heat insulating material. Among various heat insulating materials, xerogel is a heat insulating material that has a lower thermal conductivity than static air and has a very high heat insulating performance. The xerogel produced by using supercritical drying in the xerogel drying step is called an aerogel, and in the present invention, the aerogel is also included in the xerogel.

The details of the xerogel will be briefly described with reference to the drawings. The xerogel is obtained by gelating water glass or a metal alkoxide such as tetramethoxysilane under a certain condition and evaporating and drying the solvent inside. What is normally dried with hot air shrinks due to the surface tension of the solvent when it dries, and does not function as a heat insulating material. However, when the gel surface is made hydrophobic, and the solvent is replaced with a solvent having a small surface tension such as toluene, acetone, or hexane, and dried with hot air, the surface tension hardly works, and as shown in FIG. 2, about 1 to 10 nm. Silica primary particles 31 having a diameter of 5 are aggregated to form an aggregate having an interparticle distance 32 of about 40 to 100 nm. Therefore,
The inter-particle distance 32 forms pores and becomes a porous body.
Since this 40 to 100 nm is about the same size as the mean free path of air molecules, heat conduction due to collisions between air molecules becomes small, and xerogel exhibits high heat insulation performance. Then, the aggregate of these primary particles forms secondary particles of about 1 μm to 10 mm. This becomes a powdery or granular heat insulating material.

Next, a method of mounting the xerogel on the electric water heater will be described with reference to the drawings. In order to mount the heat insulating material on the electric water heater, there is a method of putting the powder or granular heat insulating material in a metal container or a fibrous bag. However, there was a problem that when placed in a metal container, the heat leaked through the metal container itself was large, and because a fibrous bag could not have a complicated shape, there was a seam between the heat insulating materials and the heat leaked from that part. .

There are many methods for solidifying a powdery substance using a binder, but it is very difficult to solidify while maintaining high heat insulation performance. This is because if the binder is added too much, the heat insulation performance is extremely deteriorated. If the amount of the binder is decreased, the solidified heat insulating material has a low strength. Therefore, the selection of the binder, the ratio of the binder and the heat insulating material, the particle size of the binder, the mixing method of the heat insulating material and the binder, etc. are important factors.

In the present invention, a method using a water-soluble organic binder and a method using a thermoplastic resin binder or a thermosetting resin binder are used as a method for solidifying the xerogel without deteriorating the heat insulation performance and mounting it on an electric water heater. Invented

A method using a water-soluble organic binder will be described. The xerogel used as a heat insulating material is substantially hydrophobized in the manufacturing process. Therefore, when the xerogel is mixed with the aqueous solution in which the water-soluble binder is dissolved, the xerogel repels water and cannot be mixed. Therefore, the water-soluble binder particles and the silica secondary particles of xerogel are uniformly mixed in advance, and the mixture is kneaded while adding water to form a clay, which is applied to a water storage container and then water is removed. The heat insulating material and the container 2 can be integrated.

As a concrete method, for example, by using the apparatus shown in FIG. 3, the water-soluble binder particles and the silica secondary particles of xerogel are uniformly mixed and kneaded while adding water to obtain a clay-like material. The clay-like heat insulating material 34 is blown out from the nozzle 33 onto the sheet 35, the roller 36 is rotated, and the thickness is controlled by the knife 37, so that the water is transferred to the water storage container 38. Then, the container 2 integrated with the heat insulating material can be realized by removing moisture by drying or the like.

As a mixing method, the heat insulating material and the water-soluble binder are mixed in the same container, and mixed using a mixer or a mix rotor so as to be as uniform as possible.
The kneading method is not particularly limited as long as the xerogel and the water-soluble binder can be kneaded.

The size of the water particles to be added is preferably as small as possible, and preferably in the form of drops or mist. In particular, it is optimal to add it in the form of a mist having a water particle size equal to or smaller than the water-soluble binder particle size. When the size of the water particles is large, a plurality of water-soluble binder particles are melted at once, forming an aggregate of the water-soluble binder particles, the binder particles are unevenly distributed, and the strength of the place where the binder is small is weak, It does not solidify. Also, to prevent this situation,
When the amount of the water-soluble binder is increased, the heat insulation performance is extremely deteriorated.

The amount of water added is not particularly limited, but it is preferable that the amount is as small as possible. If the amount of water is too large, the binder particles will be biased, the strength will be weak where there is little binder, and bubbles will remain when water is removed, leading to poor heat insulation performance.

Furthermore, when water is added by steam, water can be supplied in a state where the water particle size is very small, and there is no uneven distribution of binder particles, and solidification can be achieved while maintaining high heat insulation performance. Moreover, since the water-soluble binder can be supplied at a high temperature, the solubility of the water-soluble binder is increased, and finally the amount of water to be removed is small.

The type of the water-soluble organic binder is not particularly limited, but preferably, it is a solid at room temperature and normal pressure, has a high solubility in water, and has a high viscosity when dissolved.
Those having a high thermal decomposition temperature and those having a small thermal conductivity are preferable.
Examples of these include water-soluble celluloses represented by methyl cellulose and hydroxypropyl cellulose (referred to as HPC in this embodiment).

The size of the water-soluble binder particles is preferably as small as possible, and preferably smaller than the size of the xerogel particles. By doing so, the dispersibility of the water-soluble binder is improved, and it becomes easier to mix it more uniformly.

The mixing ratio of the water-soluble binder and the heat insulating material is not particularly limited, but is preferably 30 w of the binder.
It is preferably about t% or less. When the amount of the binder is increased, heat flows through the binder, so that the heat insulation performance deteriorates. Also,
If the amount of binder is reduced, solidification will not be possible or strength will be reduced.

Next, a method using a thermoplastic resin binder or a thermosetting resin binder will be described. Put the heat insulating material and the binder in the same container, and use a mixer or a mix rotor to mix them as evenly as possible.

As the binder, there are resin binders such as phenol resin, silicone resin, polyethylene and polypropylene, and inorganic binders such as sodium silicate powder and phosphate powder. It is better to use a resin binder
Pressure molding and injection molding are possible, good moldability,
According to the shape of the mold, it can be solidified into a free shape, and a molded product with appropriate flexibility can be obtained.

A resin binder is used as a binder, and after being mixed with a heat insulating material, it is put into a mold and heated to melt the binder and solidify the heat insulating material powder. At this time,
The pressure applied to the mold is not particularly limited. At this time, in particular, when a thermosetting resin such as a phenol resin or a silicone resin is used, the heat insulating material after solidification can be used without losing its shape even at a high temperature of about 300 ° C. Therefore, by using a mold in the shape of the container 2 in advance, a solidified heat insulating material is prepared in the shape of the container 2, and the container is mounted so as to cover the water storage container. Can be used as a container.

The average particle size of the resin binder is preferably as small as possible, and at least smaller than the average particle size of the heat insulating material. This is to increase the dispersibility of the binder and facilitate more uniform mixing.If the binder particle size is extremely large, the binder deformed by heat after heat is applied is as thick as the heat insulating material particles. This is because heat flows through the resin binder and deteriorates the heat insulating performance of the solidified heat insulating material.

The mixing ratio of the binder and the heat insulating material is not particularly limited, but preferably 50 wt% of the binder.
% Or less is preferable. When the amount of the binder is increased, heat flows through the binder, so that the heat insulation performance deteriorates. Further, if the amount of the binder is reduced, it cannot be solidified or the strength becomes low.

The effect of adding the fibrous substance will be described with reference to the drawings. By adding the fibrous substance to the binder and the heat insulating material, the strength can be increased without deteriorating the heat insulating performance. At this time, a state in which the fibrous substance is entangled with the binder is shown in FIG. Xerogel silica secondary particles 4
Even if one is not bound by the water-soluble binder 42, the water-soluble binder 42 bound by the silica secondary particles 41
Since the fibrous substances 43 can bind each other, as a result, the silica secondary particles of the xerogel can be bound, so that the strength can be increased by adding the fibrous substance. Moreover, the amount of the fibrous substance to be added is not particularly limited.

As the fibrous substance, there are glass fiber, polyester fiber, metal fiber, kynol fiber, carbon fiber and the like. Especially when glass fiber or kynol fiber is used, solidified heat insulating material should be used at high temperature. Moreover, since they have lower thermal conductivity than metal fibers, they are optimal for use as heat insulating materials.

Further, when carbon fibers are used, infrared rays are absorbed, so that the heat insulating performance at high temperatures can be further improved.

In addition, an infrared-reflecting substance such as a metal oxide typified by titanium oxide, ATO (antimony oxide-doped tin oxide), ITO (indium oxide-doped tin oxide), or the like is mixed, pulverized coal, carbon black, or the like. If a substance that absorbs infrared rays is mixed, the heat insulation performance at high temperatures can be further improved. When a water-soluble binder is used, if a dye or the like that absorbs infrared rays is dissolved in water to be added in advance, the substance that absorbs infrared rays can be more uniformly dispersed during kneading.

In this embodiment, xerogel has been described as an example of the elementary heat insulating material, but as the elementary heat insulating material, an inorganic material (for example, silica gel) which becomes porous by drying.
Alternatively, ceramics, heat-resistant sponge-like substance, steel wool, etc. may be used.

The operation of this embodiment will be described below. Container 2
When water is put into the container and then energized, the temperature of the water in the container 2 is measured by the temperature detector 14, the signal is sent to the control device 19, and the control device starts to energize the heater 13. When the water in the container 2 boils, the power supply to the heater 13 ends. After that, in response to the signal from the temperature detector 14, the control device 19 controls the heater 13 so that the temperature of the container 2 becomes substantially constant. When tapping, the push button 16 is pushed. The motor 7 operates and the water in the container 2 is discharged by the pump 8 through the hot water outlet pipe 11 from the hot water outlet 12 to the outside of the electric water heater for use. The following is an example of an experiment relating to an electric water heater equipped with a solidified heat insulating material.

<Experimental Example 1> Xerogel powder having an average particle size of 40 μm was selected as the heat insulating material, and HPC was selected as the water-soluble binder. 180 g of xerogel and 20 g of HPC were mixed with a mixer and kneaded while adding water by spraying to prepare a clay-like mixture of xerogel and a water-soluble binder. Next, the mixture is evenly applied to the outside of the container 2, and the whole container 2 is placed in a constant temperature bath at 80 ° C., and water is removed by drying with hot air to produce a container 2 integrated with a heat insulating material. did. An electric water heater having this container 2 (hereinafter referred to as a water-soluble product in this embodiment) was prepared.

Next, a xerogel powder having an average particle size of 40 μm was selected as the heat insulating material, and a phenol resin, Bellpearl (manufactured by Kanebo), was selected as the resin binder. Xerogel 180
g and Bellpearl 20g are mixed with a mixer, and then
Put in a mold in the shape of container 2, gradually raise the temperature of the mold by a heater, and heat up to 200 ° C in about 40 minutes,
The temperature was maintained at 200 ° C. for about 10 minutes, and the temperature was cooled to room temperature by a water cooling device in about 15 minutes. Then, the mold was opened and the sample taken out was attached to the container 2. An electric water heater having this container 2 (hereinafter referred to as a phenol product in this embodiment) was prepared.

In addition, as a conventional example, a bag made of a non-woven fabric of polyethylene terephthalate and an electric water heater (hereinafter referred to as a conventional product 1 in this embodiment) which is packed in a stainless steel container and filled with a xerogel powder having an average particle size of 40 μm and mounted in the container 2. A xerogel powder having an average particle size of 40 μm was packed in a container, and an electric water heater (hereinafter referred to as a conventional product 2 in this example) mounted on the container 2 was prepared in a state having a seam as shown in FIG.

Water was put into each of these four types of electric water heaters, and the heat insulation power of each was measured. The temperature of the heat retaining water was 96.5 ° C and the ambient temperature was 20 ° C. The measurement was performed after reaching a sufficient equilibrium state. The experimental results are shown in (Table 1).

[0050]

[Table 1] Therefore, by integrating the heat insulating material and the container 2 by the method according to the present invention, it is possible to realize an electric water heater in which the heat insulating power is significantly reduced.

<Experimental Example 2> Xerogel powder having an average particle size of 40 μm was selected as the heat insulating material, HPC was selected as the water-soluble binder, and glass fiber was selected as the fibrous substance. Xerogel 18
A mixture of 0 g and 20 g of HPC with a mixer (hereinafter, referred to as 0% product in this embodiment), xerogel 171 g
And a mixture of 19 g of HPC and 10 g of glass fiber with a mixer (hereinafter referred to as 5% product in this example), a mixture of 162 g of xerogel, 18 g of HPC and 20 g of glass fiber with a mixer (hereinafter, 10% in this example).
Product), a mixture of 144 g of xerogel, 16 g of HPC and 40 g of glass fiber with a mixer (hereinafter referred to as 20% product in this example), 126 g of xerogel and H.
A mixture of 14 g of PC and 60 g of glass fiber with a mixer (hereinafter referred to as 30% product in this example), a mixture of 90 g of xerogel, 10 g of HPC and 100 g of glass fiber with a mixer (hereinafter referred to as 50% product in this example). Prepared. Then, each was kneaded while adding water by spraying to produce a clay-like substance.

Next, each clay-like substance is evenly coated on the outside of the container 2, and the whole container 2 is placed in a constant temperature bath at 80 ° C., and moisture is removed by hot air drying to integrate with the heat insulating material. The individualized containers 2 were produced. Each electric water heater having this container 2 was prepared.

Water was put into each of these six types of electric water heaters, and the heat insulating power of each was measured. The temperature of the heat retaining water was 96.5 ° C and the ambient temperature was 20 ° C. The measurement was performed after reaching a sufficient equilibrium state. The experimental results are shown in (Table 2).

[0054]

[Table 2] Therefore, when the heat insulating material and the container 2 are integrated by the method according to the present invention, by adding the fibrous substance, the strength of the heat insulating material is improved, so that the durability is higher and the heat insulating power is significantly reduced. It is possible to realize the electric water heater.

<Experimental Example 3> Xerogel powder having an average particle diameter of 40 μm was selected as the heat insulating material, HPC was selected as the water-soluble binder, and glass fiber was selected as the fibrous substance. Furthermore, titanium oxide was selected as a substance that reflects infrared rays, and carbon black was selected as a substance that absorbs infrared rays. Xerogel 17
A mixture of 1 g, 19 g of HPC and 10 g of glass fiber (hereinafter referred to as a normal product in this example), a mixture of 171 g of xerogel, 19 g of HPC, 10 g of glass fiber and 10 g of titanium oxide (hereinafter referred to as the present embodiment). In the example, a titanium oxide product), a mixture of 171 g of xerogel, 19 g of HPC, 10 g of glass fiber and 10 g of carbon black (hereinafter referred to as a carbon product in this example) were prepared.
And knead while adding water to each by spraying,
A clay-like material was made.

Next, each clay-like substance is evenly applied to the outside of the container 2, and the whole container 2 is placed in a constant temperature bath at 80 ° C., and moisture is removed by drying with hot air, whereby it is integrated with the heat insulating material. The individualized containers 2 were produced. Each electric water heater having this container 2 was prepared.

Water was put into these three types of electric water heaters, and the heat insulating power of each was measured. The temperature of the heat retaining water was 96.5 ° C and the ambient temperature was 20 ° C. The measurement was performed after reaching a sufficient equilibrium state. The experimental results are shown in (Table 3).

[0058]

[Table 3] Therefore, when the heat insulating material and the container 2 are integrated by the method according to the present invention, by adding a substance that reflects infrared rays or a substance that absorbs infrared rays, it is possible to realize an electric water heater with a significantly reduced heat insulating power. You can

[0059]

As described above, according to the inventions described in claims 1 to 6 and 8, the heat insulating material having a high heat insulating property whose heat conductivity is equal to or lower than that of still air deteriorates its heat insulating performance. Without solidification, it can be solidified into various shapes, and since the solidified heat insulating material can cover and integrate the water storage container,
The seam can be eliminated, and heat can be prevented from leaking from the seam, and an energy-saving electric water heater with low heat insulation power can be realized.

Further, according to the invention of claim 7, since the strength of the heat insulating material integrated with the water storage container is improved, it is possible to realize an energy-saving electric water heater having a higher durability and a smaller heat insulating power.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an electric water heater according to a first embodiment of the present invention.

FIG. 2 is an enlarged schematic view of a part of the silica xerogel in Example 1 of the present invention.

FIG. 3 is a schematic diagram of an apparatus that integrates a water storage container of the electric water heater and a heat insulating material according to the first embodiment of the present invention.

FIG. 4 is an enlarged schematic view of a part of the solidified heat insulating material in Example 1 of the present invention.

FIG. 5 is a vertical cross-sectional view of a water storage container of an electric water heater according to a conventional technique.

[Explanation of symbols]

2 Water storage container 20 insulation 34 Clay insulation 41 Silica secondary particles 42 Water-soluble binder particles 43 Fibrous substances

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takashi Hashida             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Yasutomo Funakoshi             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Toshihiro Matsumoto             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 4B002 AA12 BA53 CA21 CA31 CA34                 4B055 AA34 BA23 BA27 CA15 CC58                       FA01 FB32 FC05 FC11 FC20                       FD02 FE03 FE10

Claims (8)

[Claims] 1. A water storage container, a heater for heating water in the water storage container, a hot water outlet passage for discharging the water, and a base heat insulating material that are bound by a binder to have a thermal conductivity of air whose thermal conductivity is still. An electric water heater having the following heat insulating material, wherein the heat insulating material seamlessly covers the water storage container. 2. The electric water heater according to claim 1, wherein the heat insulating material and the water storage container are connected by a binder. 3. The electric water heater according to claim 1, wherein the elementary heat insulating material has hydrophobicity and has a porous body, and the binder is a water-soluble organic binder. 4. A water storage container, a heater for heating water in the water storage container, a hot water outlet path for letting out water, and a heat insulating material having a thermal conductivity equal to or lower than that of stationary air. Then, water is added to the mixture of the hydrophobic and pore-containing heat insulating material and the water-soluble organic binder, and the mixture is kneaded, then applied to the water storage container, and the heat insulating material is attached by removing the water. Electric water heater. 5. A water storage container, a heater for heating water in the water storage container, a hot water outlet passage for letting out water, and a heat insulating material having a thermal conductivity equal to or lower than that of stationary air. An electric water heater equipped with the heat insulating material as a molded body that adheres to the water storage container by applying pressure and temperature to a mixture of the base heat insulating material and the resin binder. 6. The electric water heater according to claim 1, wherein the elementary heat insulating material is silica xerogel. 7. The electric water heater according to any one of claims 1 to 6, which has a base heat insulating material or a binder and a fibrous substance that binds or is entangled with each other. 8. A material containing at least one of a substance that reflects and absorbs infrared rays.
The electric water heater according to claim 1.