JP2003343917A - Electric water heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric water heater which can prevent the generation of noise even if scales are generated in a tank. <P>SOLUTION: A heater 30 of the electric water heater 10 for heating and storing the supplied water in the hot-water storage tank 20 in the condition possible to be taken out is fitted to heat the only central part of a bottom surface of the hot-water storage tank 20, and a non-heating part is provided in the peripheral part of the bottom surface. Shape of the bottom surface of the hot-water storage tank 20 and shape of the heater 30 are formed different from each other. <P>COPYRIGHT: (C)2004,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 that heats water supplied in a tank and stores it in a state where it can be taken out.

[0002]

2. Description of the Related Art Conventionally, an electric water heater has been used which supplies water into a tank, heats the water to a predetermined temperature and stores it in a state where it can be taken out. There is one disclosed in Kaihei 11-342080. A heating base having a heater embedded therein is attached to the bottom surface of the tank of the electric water heater to heat the entire surface of the bottom surface of the tank excluding the tap hole. Further, this electric water heater is equipped with a water supply port, a hot water outlet, a liquid level sensor and a temperature sensor.

[0003]

By the way, in the above electric water heater, when water containing a large amount of calcium ions is used, scales (scales) may be generated and deposited on the bottom of the tank. Therefore, in the conventional electric water heater, there is a problem that when the water is boiled, the bubbles generated on the bottom surface of the tank tend to come out of the scale and make an abnormal noise.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an electric water heater that does not make noise even when scale is generated in the tank. .

In order to achieve the above object, the electric water heater according to the present invention is characterized in that a predetermined amount of water is supplied into a tank, and the water can be heated to a predetermined temperature by a heater and taken out. In the electric water heater that stores in such a state, the heater is attached so as to heat the central portion of the bottom surface of the tank, and the non-heating surface is provided on the outer peripheral portion of the bottom surface.

According to the structure of the present invention constructed as described above, the heating surface heated by the heater is formed in the central portion of the bottom surface of the tank, and the non-heating surface which is not heated is formed on the outer peripheral portion of the bottom surface of the tank. For this reason, when the water in the tank is heated, convection occurs in the water, which rises from the heating surface in the central portion of the tank bottom surface and descends to the non-heating surface in the outer peripheral portion of the tank bottom surface. Therefore, the scale generated in the tank is
Accumulates on the non-heated surface at the bottom of the tank that is less susceptible to convection. Further, the place where the bubbles are generated on the bottom surface of the tank is the heating surface on which the scale does not accumulate, and the generated bubbles rise from the heating surface to float on the molten metal surface and disappear. Therefore, the generation of abnormal noise due to the bubbles rising out of the scale is eliminated.

Another structural feature of the electric water heater according to the present invention is that the bottom shape of the tank is different from the planar shape of the heater. As the tank and the heater in this case, a tank having a square bottom shape and a disk heater, a tank having a circular bottom shape and a square plate heater, and others such as a circle, an ellipse, a triangle, and a triangle A combination of a tank having a bottom surface of various shapes such as a polygon and a heater can be used. According to this, since the non-heated surface is always formed on the outer peripheral portion of the bottom surface of the tank, it is possible to effectively prevent the generation of the abnormal noise generated when the bubbles rise out of the scale.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an electric water heater according to the present invention will be described below with reference to the drawings. FIG. 1 shows an electric water heater 10 according to the same embodiment. The electric water heater 10 heats water supplied from the outside into hot water, and stores the hot water in a removable state. The electric water heater 10 has a box-shaped case body 11a and a lid 11b. The hot water storage tank 20 is housed. A water supply pipe 12 for connecting an external water pipe and an upper end side portion of the hot water storage tank 20 is attached to the inside of the case portion 11. The water supply pipe 12 and the hot water storage tank 20 are connected to the inside of the hot water storage tank 20 at a connecting portion between the water supply pipe 12 and the hot water storage tank 20. A water supply member 13 having an opening / closing valve for supplying water is provided.

At the lower end portion of the hot water storage tank 20 inside the case portion 11, a spout pipe 1 extending outside the case portion 11 is provided.
4 is provided, and a pouring handle 15 for taking out hot water from the hot water storage tank 20 is attached to the tip of the pouring pipe 14. Further, at the lower end of the outer surface of the case portion 11 below the pouring handle 15, the pouring handle 1
A container stand 16 for placing a container for receiving hot water discharged from the spout pipe 14 when the container 5 is opened is provided. Further, below the hot water storage tank 20 in the case portion 11, an electric equipment box 17 in which an electric control circuit for controlling the electric water heater 10 and the like are housed is provided.

As shown in FIGS. 2 and 3, the hot water storage tank 20 is a rectangular box-shaped tank body 2 made of stainless steel.
The tank portion 21 includes a lid 1a and a lid 21b, and heat insulating materials 22a and 22b are attached to the outer surface of the tank body 21a and the upper surface of the lid 21b, respectively. A bottom plate 22c is provided at the lower end of the heat insulating material 22a with a space from the bottom surface of the tank body 21a. Further, the water supply port 13a side portion of the water supply member 13 projects from the upper end portion of one inner side surface of the tank body 21a, and the rear end side portion of the spout pipe 14 projects from the lower end side portion of the inner side surface. ing. The rear end portion of the spout pipe 14 is a spout 14a.
Is bent downward.

On the lower surface of the lid 21b, a pair of pipe-shaped vertical axes 23 and 24 extending to the lower side in the tank main body 21a are attached, and the vertical axis 23 is attached to the first float switch 2
5 and the second float switch 26 is provided on the vertical axis 24. The first float switch 25 has a vertical axis 2
3, a cylindrical float 25a slidably attached vertically along the outer peripheral surface of the shaft 3, a flange-shaped lower contact 25b fixed to the lower side of the vertical axis 23, and an upper side of the vertical axis 23 fixed. And a flange-shaped upper contact 25c. Then, the float 25a moves up and down along the vertical axis 23 in accordance with the change in the water level in the tank portion 21, contacts the lower contact 25b, detects the set lower limit water level, and contacts the upper contact 25c. The upper limit water level set by is detected.

The second float switch 26, like the first float switch 25, has a cylindrical float 26a, a flange-shaped lower contact 26b, and a flange-shaped upper contact 2.
6c, the lower contact 26b and the upper contact 26c are provided on the vertical axis 24 so as to correspond to substantially central positions of the lower contact 25b and the upper contact 25c. The interval between the mounting positions of the lower contact 26b and the upper contact 26c is set to be slightly wider than the height of the float 26a. The second float switch 26 detects an intermediate position between the set upper and lower limit water levels, and the float 26a that was in contact with the lower contact 26b is not connected to the lower contact 26.
It detects that the water level has reached the intermediate position when it is separated from b, and that the water level has exceeded the intermediate position when the float 26a contacts the upper contact 26c.

An electric control circuit or the like in the electrical equipment box 17 opens and closes an opening / closing valve built in the water supply member 13 according to the positions of the floats 25a and 26a in the first and second float switches 25 and 26. Therefore, for example, when the float 25a comes into contact with the lower contact 25b, the opening / closing valve opens to start water supply, and the float 25a moves to the upper contact 25c.
When it comes into contact with, the on-off valve can be closed to stop the water supply. Further, the contact between the float 26a and the lower contact 25b, or the contact between the float 25a and the upper contact 25
It is also possible to control the opening and closing of the open / close valve by the contact of c.

The lead wires 2 connected to the first and second float switches 25 and 26 are provided inside the vertical axes 23 and 24.
7 is accommodated and the upper end side thereof extends to the outside of the hot water storage tank 20. A thermistor (not shown) for detecting the temperature of the hot water held in the tank 21 is provided at the lower end of the vertical axis 23. The lead wire of this thermistor also extends outside along with the lead wire 27 through the inside of the vertical axis 23. The lower end surfaces of the vertical axes 23 and 24 are closed to prevent hot water from entering.

On the other inner surface side of the tank body 21a, an overflow pipe 28 is vertically arranged along the inner surface of the tank body 21a. The position of the upper end of the overflow pipe 28 is slightly higher than the position of the upper contact 25c of the first float switch 25, and the lower end thereof is the bottom surface of the tank body 21a and the bottom plate 22.
It extends through c to the outside of the hot water storage tank 20. Therefore, when water is supplied to the hot water storage tank 20 beyond the upper end of the overflow pipe 28, an excess amount exceeding that is discharged from the overflow pipe 28 to the outside.

A discharge pipe 29 for discharging water or hot water in the tank body 21a is provided at the center of the bottom surface of the tank body 21a, so that when the scale is accumulated in the tank body 21a, Is discharged together with water and hot water. A heater 30 is attached between the bottom surface of the tank body 21a and the bottom plate 22c. The heater 30 is configured by embedding a heater wire inside a disc-shaped aluminum plate, and as shown in FIGS. 3 and 4, a hole portion 30a provided in the central portion.
The discharge pipe 29 is inserted into the tank main body 21a and is attached to the center of the bottom surface of the tank main body 21a. A non-heated portion that is not heated by the heater 30 is formed outside the center of the bottom surface of the tank body 21a.

The heater 30 is energized based on a set temperature, and is repeatedly turned on and off according to the hot water temperature detected by the thermistor to maintain the hot water temperature at the set temperature. Further, the electric water heater 10 is also equipped with a power switch and an operation unit having operation buttons for setting temperature and water level.

In this configuration, when the electric water heater 10 is used, the power switch is turned on and the temperature and water level (here, the position of the upper contact 25c is set as the upper limit) are set by operating each operation button. To do. As a result, the opening / closing valve of the water supply member 13 is opened, and the water of the water pipe is supplied into the tank portion 21 through the water supply pipe 12 and the tank portion 2
The water level in 1 rises. Then, when the water level reaches the lower contact 25b of the first float switch 25, the heater 30 is energized to start heating the water.

The water supply is continued until the water level in the tank portion 21 reaches the lower contact 26b of the second float switch 26, and the float 25a is separated from the lower contact 26b or the float 25a contacts the upper contact 26c. It is temporarily stopped. Then, the water is heated by the heater 30 until the hot water temperature reaches the set temperature. When the hot water temperature reaches the set temperature, water supply is started again and the tank portion 21
The water level inside is the upper contact 25 of the first float switch 25.
Continue watering until it reaches c. And float 25a
When comes into contact with the upper contact 25c, the on-off valve is closed and water supply is stopped. During this time, the heater 30 is intermittently turned on / off, and the on-off valve is also intermittently opened / closed, so that the hot water in the tank portion 21 rises to a set temperature while keeping the hot water temperature above a predetermined temperature. To be done.

The hot water temperature in this case is detected by the thermistor, and the hot water heater 30 is turned on / off based on the detection value of the thermistor to raise the hot water temperature to a set temperature and maintain it at that temperature. When using the hot water in the hot water storage tank 20, the hot water can be taken out by placing a container (not shown) on the container holder 16 and opening the pouring handle 15. Further, when the amount of hot water decreases due to use, the water level in the hot water storage tank 20 drops, and the float 25a contacts the lower contact 25b, the open / close valve opens and water is supplied from the water supply pipe 12 into the hot water storage tank 20. .

Then, the water is heated in the hot water storage tank 20 to become hot water, which is taken out from the pouring handle 15 and used repeatedly. In the meantime, as shown in FIG. 4, scale 31 is generated in the tank body 21a by the calcium ions contained in the water and is deposited on the bottom surface of the tank body 21a. This electric water heater 10
In the above, since the heater 30 is formed in a disk shape and attached to the center of the bottom surface of the tank body 21a, the water in the tank body 21a is heated at the center of the bottom surface of the tank body 21a. Therefore, the tank body 21a
In the hot water inside, convection that rises from the center of the bottom surface of the tank body 21a and descends from the side is generated.

As a result, the scale 31 generated in the tank body 21a is deposited on the bottom surface of the tank body 21a where the flow of hot water due to convection hardly occurs, that is, at the four corners and in the vicinity thereof. Therefore, even if air bubbles are generated on the bottom surface of the tank body 21a when the water is boiled, the air bubbles rise in the water from the center of the bottom surface of the tank body 21a and disappear on the water surface. Therefore, the scale 31 is not agitated by the air bubbles and no abnormal noise is generated. When the scale 31 deposited on the bottom surface of the tank body 21a becomes large, the operation of the electric water heater 10 is stopped, and the discharge pipe 29 is opened to discharge the scale 31 together with water or hot water. 21 can be cleaned.

As described above, according to the electric water heater 10, since the central portion of the bottom surface of the tank body 21a is heated by the heater 30 and the four corners other than the central portion of the bottom surface are not heated, the bottom surface of the tank body 21a is not heated. , A non-heated surface on which the scale 31 is deposited and a heated surface on which bubbles are generated by heating. Therefore, it is possible to prevent generation of abnormal noise due to bubbles rising out of the scale 31.

Further, in the above embodiment, the tank portion 21 is formed in a rectangular box shape and the heater 30 is formed in a disk shape, but this shape can be appropriately changed. For example, the tank body may be formed into a cylindrical shape with a bottom, and the heater may be formed into an elliptical, triangular, or quadrangular plate shape that fits within the circle on the bottom surface of the tank body. It is formed into an elliptical cylinder, and the heater is a circle with a size that fits within the ellipse of the bottom of the tank body.
It can also be formed in a triangular or quadrangular plate shape. In this way, by using a tank portion having a predetermined shape and a heater that is set to a size that fits within the bottom surface of the tank portion and is formed in a shape different from the bottom surface shape of the tank,
A non-heated surface can be formed on the outer peripheral portion of the bottom surface of the tank.

Furthermore, by making the area of the heating surface of the heater smaller than the area of the bottom surface of the tank portion, the shape of the bottom surface of the tank portion and the shape of the heater can be made the same. In any of these modified examples, the scale is deposited on the non-heated surface on which the heater is not provided, so that no abnormal noise is generated.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an electric water heater according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a hot water storage tank provided in the electric water heater shown in FIG.

FIG. 3 is a bottom view of the hot water storage tank shown in FIG.

FIG. 4 is a cross-sectional view showing a lower portion of the hot water storage tank and a heater.

[Explanation of symbols]

10 ... Electric water heater, 12 ... Water supply pipe, 14 ... Discharge pipe, 15
... pouring handle, 20 ... hot water storage tank, 21 ... tank part, 30 ... heater.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3L025 AD10                 4B004 AA11 BA03 BA06

Claims (2)

[Claims] 1. An electric water heater which supplies a predetermined amount of water into a tank, heats the water to a predetermined temperature with a heater, and stores the water in a state where it can be taken out, wherein the heater is the center of the bottom surface of the tank. An electric water heater characterized in that a non-heated surface is provided on an outer peripheral portion of the bottom surface, which is attached so as to heat the portion. 2. The electric water heater according to claim 1, wherein the bottom shape of the tank and the planar shape of the heater are different from each other.