JPH01285218A - Electric water heater - Google Patents

Abstract

PURPOSE:To insulate heat at different temperature for the purpose of a user by providing a hot water temperature lowering detecting means for starting to heat and boiling when the temperature of the hot water is lowered from a previously set temperature and a water boiling switch for heating and boiling according to a necessity. CONSTITUTION:An annular heater 2 is provided on the bottom face of a container 1 for storing water and a thermistor 3 is pressed to the center of the bottom part of the container 1 and connected to a temperature detecting means 4. The output of the temperature detecting means 4 is inputted to a heat insulation control means 5 to control the energization of the heater to the temperature set by a heat insulation temperature selecting means 6. By pressing a water boiling switch 8 by a heating control means 9, the heater 2 is energized to heat and boil the water in the container 1. A second thermistor 10 connected to a boiling detecting means 11 is attached to a steam path 13 provided in a cover 12, is ordinarily hardly heated too much but heated to a high temperature only when the water in the container 1 is boiled and steam passes through the steam path 13, so that the boiling detecting means 11 detects it, transfer a signal for detecting the boiling to the heating control means 9 to stop the heating.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electric water heater that heats water to boil it and then keeps it warm.

BACKGROUND OF THE INVENTION In conventional electric water heaters of this type, the temperature at which the water is kept warm after boiling is predetermined and cannot be changed.

Problems to be Solved by the Invention The heat retention temperature after boiling in conventional electric water heaters is approximately 90℃.
Because the temperature is extremely high (between 96°C and 96°C), when used to brew high-grade tea such as Gyokuro, there was a problem in that the original flavor would not come out. In addition, when making milk for infants, there was the problem that after the milk had been melted, it had to be cooled down until it became so-called human skin.

In view of these problems, an object of the present invention is to provide an electric water heater that allows you to select the heat retention temperature after heating and boiling. The purpose is to provide equipment.

Means for Solving the Problems In order to achieve the above object, the electric water heater of the present invention has the following features:
It is provided with a heat retention temperature selection means that can select one of two or more predetermined temperatures as the heat retention temperature.

The present invention also includes a water temperature drop detection means that starts heating again to bring the water to a boil when the water temperature drops to a predetermined temperature or higher than the temperature selected by the heat retention temperature selection means, and a water temperature drop detection means that starts heating the water again to bring it to a boil. It is also equipped with a water boiler switch.

If the hot water is heated by the water temperature drop detection means, it will be kept warm after boiling at the original temperature, that is, the temperature selected by the heat retention temperature selection means, and if it is heated by the water boiler switch, after boiling, it will be kept warm. The temperature is maintained at the highest temperature that can be selected by the temperature selection means.

Function: In the electric water heater configured as described above, the heat retention temperature can be selected from predetermined temperatures depending on the purpose of using the hot water. Furthermore, if the temperature of the hot water decreases by adding water, the temperature is kept at the temperature selected by the heat retention temperature selection means after being heated to boiling temperature.

On the other hand, when the water boiler switch is pressed, the water is heated and then kept at the highest temperature.

Embodiments Hereinafter, embodiments of the present invention will be described based on the accompanying drawings. FIG. 1 shows a functional block diagram of the main parts of an electric water heater according to a first embodiment of the present invention. In FIG.
A thermistor 3 is installed at the center of the bottom of the container 1.
is connected to the temperature detection means 4 by pressure contact. The output of the temperature detection means 4 is input to the heat retention control means 6, and the energization of the heater 2 is controlled in accordance with the temperature selected by the heat retention temperature selection means 6. Although not shown here, the heat retention temperature selection means 6 includes a switch and an LED (
A light emitting diode (light emitting diode) is connected, and each time the switch is pressed, a heat retention temperature is selected in sequence, and the selected temperature is displayed by lighting up the corresponding LED.

Reference numeral 8 denotes a water boiling switch provided in the display/operation section 7, which is connected to the heating control means 9. and heating control means 9
When the water boiler switch 8 is pressed, the heater 2
The water in the container 1 is heated and boiled by applying electricity to the container 1. 1o is a second thermistor connected to the boiling detection means 11, and this second thermistor 1o is connected to the steam passage 13 provided in the lid 12.
It is attached to. Also, this second thermistor 10
is provided near the outlet of the steam passage 13,
Normally, it does not get very hot, but only when the water in the container 1 boils and the steam passes through the steam passage 13, it becomes extremely hot. A boiling detection signal is transmitted, and thereby the heating control means 9 stops heating.

FIG. 2 shows a circuit diagram of the main parts of the first embodiment of the present invention, and the same components as in FIG. 1 are given the same numbers. The temperature detection means 4, the heat retention control means 5, the heat retention temperature selection means 6, and the heating control means 9 are realized by a one-chip microcomputer (hereinafter referred to as microcomputer) 14.

3(a) and 3(b) are characteristic diagrams for explaining the operation of the temperature detecting means 4. In FIG.
The voltage divided by the resistor 16 is transferred to the comparator 17.
The temperature of the thermistor 3 can be determined by sequentially grounding the resistors 18, 19, 20.21, whose constants are determined corresponding to a predetermined heat retention temperature, by the temperature detecting means 4. In the example of FIG. 3(a), Φ), the temperature of the thermistor 3 is such that when the resistors 18 and 1e corresponding to the first and second highest temperatures are grounded, the output of the comparator 17 becomes High, and the temperature of the thermistor 3 becomes High. When the resistors 2o and 21 corresponding to the highest temperature and the fourth highest temperature are grounded, the output of the comparator 17 remains low, so the temperature detected by the thermistor 3 is lower than the second predetermined temperature, and Therefore, it can be determined that the temperature is higher than the third predetermined temperature.

Next, other embodiments of the present invention will be described. FIG. 4 shows a functional block diagram of the main parts of an electric water heater according to a second embodiment of the present invention. FIG. 6 shows a circuit diagram of the same essential parts, and this is also the same as the embodiment of the present invention except that a hot water temperature drop detection means 22 is added. In this figure 6, the resistance is 1 day.

19 and 20 are the highest temperature, the second temperature, and the third temperature among the predetermined temperatures, and the resistor 21 is set to 3.
The circuit configuration is simplified by treating the second and third temperatures as the highest temperature and a predetermined temperature lower than the second temperature, respectively.

Now, for example, if the second highest temperature among the predetermined temperatures is selected by the heat retention temperature selection means 6 as the heat retention temperature, and the temperature detected by the temperature detection means 4 is higher than the second temperature. The triac 23 is triggered by the heat retention control means 5 and turned on, thereby energizing the heater 2b and slowly increasing the temperature of the water. When the temperature detected by the temperature detection means 4 eventually becomes higher than the second temperature, the heat retention control means 6 turns off the triac 23, so that the temperature of the water in the container 1 decreases to (1) in FIG. As shown in the section, it matches the set heat retention temperature with a slight ripple. Here, when water is poured into the container 1 and the temperature of the water decreases as shown in part (II) of FIG. 6, the temperature detection means 4
The water temperature is detected to be lower than the third temperature and sent to the humidity drop detection means 15. This hot water temperature drop detection means 16 uses the data sent from the temperature detection means 4 and the temperature that is lower than the heat retention temperature selected by the heat retention temperature selection means 6 by a predetermined temperature (here, as the heat retention temperature). Since the second temperature is selected,
Furthermore, the third temperature one level below is used as a comparison standard. ), it is detected that the temperature at which the hot water should be kept warm is further lower than the lower sensitivity by a predetermined temperature, and this is output to the heating control means 9. The heating control means 9 drives the transistor 24 to energize the relay coil yV25a, turns ON the relay contact 26b, and energizes the heater 2a to heat and boil the water in the container 1.

Note that even if the water temperature is not classified, the heat retention temperature selection means 6
Even if the heat retention temperature is changed by , and as a result, the hot water temperature becomes lower than the temperature that is a predetermined temperature lower than the newly selected warm water temperature, the hot water temperature drop detection means is activated in the same manner as in the above embodiment. 2 works to heat and boil the water in the container 1 by 1%, producing the same effect as in the above embodiment.

Next, a third embodiment will be described. The components and circuitry of this third embodiment are the same as the second embodiment shown in FIGS. 4 and 5. In this third embodiment, both when the water boiling switch 8 is pressed and the water in the container 1 is heated to boiling, and when heating is started by the water temperature drop detection means 22, the temperature rises. is configured to be kept warm at a predetermined temperature selected in advance by the heat retention temperature selection means 6. The electric water heater of the third embodiment is very convenient to use when the water temperature is always the same.

Next, a fourth example will be described. The components of this fourth embodiment are the same as those of the second embodiment.

In this fourth embodiment, the water temperature drop detection means 2
If heating is started by the function of 2, after boiling is detected,
When the water is kept warm at the original heat retention temperature and the heating switch 8 is pressed to start heating, the water is kept warm at the highest temperature selectable by the heat retention temperature selection means 6 after boiling. When the electric water heater of this fourth embodiment uses hot water and slightly lukewarm water, if you simply add water, the temperature setting for keeping warm will not change and after boiling, The water is kept warm at the original temperature, and when the water boiler switch 8 is pressed, the hottest water is provided after boiling, making it easier to use.

Further, a fifth example will be described. The components of this fifth embodiment are the same as those of the second embodiment. In the first to fourth embodiments described above, the heat retention temperature is selected in advance by the heat retention temperature selection means 6, but the heat retention temperature is often used without being selected in advance. Therefore, in this sixth embodiment, in such a case, the heat retention temperature after boiling is set to the highest temperature that can be selected by the heat retention temperature selection means 6. In our normal diet, we use hot water to make coffee,
It is clear that the electric water heater of the fifth embodiment is easy to use, considering the fact that it is commonly used to make tea, and that cup noodles have become popular.

Next, a sixth embodiment will be described. The components of this sixth embodiment are also the same as those of the second embodiment as well as the fifth embodiment, but in this sixth embodiment, when the heat retention temperature has not been selected in advance, , the lowest heat retention temperature among the heat retention temperatures that can be selected is set as the heat retention temperature. This is due to the reasons described below. This is because although an electric water heater can heat water in a short time, it takes a very long time for the hot water in an electric water heater to cool down. Now, assume that there are 2 liters of hot water in the container 1 and the temperature of the hot water is 70°C. Electric water heater heater 2
is usually 700 to 1000 watts, so 7
00 watts, the time t required to heat from 70°C to 100°C is: ■・Δd・work=360 (seconds) V: capacity, Δd: temperature change, P: heat amount of heater, I:
The constant is 4.2 (call/1), which is 360
seconds. In this case, the thermal efficiency will be about % head, so
Approximately 7 minutes is sufficient.

On the other hand, data investigated by the inventors shows that it takes 1 to 3 hours for hot water to reach approximately 70°C immediately after boiling. As is clear from the above reasons, if the temperature is not selected in advance and the water is suddenly heated, keeping the water warm at the lowest temperature that can be selected will allow the user to adjust the temperature of the water they should use. This is useful because it shortens the time it takes on average to provide hot water at an appropriate temperature.

Finally, a seventh embodiment will be described. The constituent elements of this seventh embodiment are the same as those of the second embodiment. In the sixth example above, it was stated that in today's food culture, there are many occasions to use hot water, but eventually, as in Europe and the United States, slightly lukewarm water was used to make coffee, and tea was also made with Gyokuro, etc. In some cases, it is common to use lukewarm water, and the most commonly used water temperature may vary depending on the lifestyle of each individual. In view of these circumstances, the electric water heater of this seventh embodiment has an initial heat retention temperature that is appropriate for each usage purpose and usage environment, regardless of regional characteristics or food culture differences. Therefore, its usability is very good.

Effects of the Invention As is clear from the description of the above embodiments, according to the present invention,
Since a heat retention temperature selection means is provided that allows one to be selected as a heat retention temperature from two or more predetermined temperatures, it is possible to maintain heat at different humidity levels depending on the user's circumstances and purpose of use. By variously changing the rules for determining the heat retention temperature after heating, it is possible to provide an easy-to-use electric water heater that transcends differences in food culture.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the main parts of an electric water heater according to the first embodiment of the present invention, Fig. 2 is a circuit diagram of the main parts, and Fig. 3 (
a) and Φ) are characteristic diagrams for explaining the operation of the temperature detection means, and FIGS. 4 and 5 are blocks of essential parts of electric water heaters in the second to seventh embodiments of the present invention. FIG. 6 is a characteristic diagram for explaining the operation of the hot water temperature drop detection means. 1... Container, 2... Heater, 4...
... Temperature detection means, 6 ... Heat retention control means, 6
... Warm temperature selection means, 8 ... Water boiler switch, 9 ... Heating control means, 11 ...
...Boiling detection means, 22... Water temperature drop detection means. Name of agent: Patent attorney Toshio Nakao and 1 other person2-
Ichi-to Ichiba 3rd cause time tl)t 已l＼1 4th prisoner 1-g number

Claims (7)

[Claims] (1) A heater, a temperature detection means for detecting the temperature of a container heated by the heater or water in the container, and a heat retention temperature selection that allows one of two or more predetermined temperatures to be selected as a heat retention temperature. means, a heat retention control means for inputting the output of the temperature detection means and keeping the temperature at a predetermined temperature selected by the heat retention temperature selection means; a water boiling switch for energizing the heater to start heating; Boiling detection means for detecting boiling of water, the boiling water switch and the output of the boiling detection means are input, and heating control that energizes the heater when the water boiling switch is pressed and stops heating when the boiling detection means outputs an output. Electric water heater with means. (2) Using the output of the temperature detection means as input, detecting that the water temperature has decreased to a predetermined temperature or higher than the temperature selected by the heat retention temperature selection means, and outputting it to the heating control means for heating. 2. The electric water heater according to claim 1, further comprising means for detecting a drop in water temperature for starting the water temperature. (3) Claim 1 or 2, wherein after the boiling is detected, the heat is kept at a predetermined temperature selected by the heat retention temperature selection means.
Electric water heater as described. (4) When heating after detecting a drop in water temperature, after boiling,
Claim 2 or 3, wherein the water is kept warm at the temperature selected by the heat retention temperature selection means, and when heated by a water boiler switch, the water is kept warm at the highest temperature selectable by the heat retention temperature selection means after boiling. Electric water heater as described. (5) When the heat retention temperature is not selected by the heat retention temperature selection means, the highest temperature among the predetermined temperatures is automatically set as the heat retention temperature. Water boiler. (6) When the heat retention temperature is not selected by the heat retention temperature selection means, the lowest temperature among the predetermined temperatures is automatically set as the heat retention temperature. Water boiler. (7) When the heat retention temperature is not selected by the heat retention temperature selection means, a predetermined specific temperature among the predetermined temperatures is set as the heat retention temperature. Electric water heater.