JPH08107824A - Electric kettle - Google Patents

Abstract

PURPOSE: To detect the proper boiling of liquid in a container irrespective of the capacity and heat retaining temperature. CONSTITUTION: There are provided a container 1 for receiving liquid, a temperature detecting means 3 for detecting liquid temperature in the receptacle, a heating means 2 for heating the liquid in the container, an electrifying means 4 for electrifying the heating means and a timing means 6 for timing and continuously clearing the time to raise every first predetermined temperature. Thus, there are provided a memory means 7 for storing the time to raise the first predetermined temperature width timed by the timing means 6, a boiling detecting means 8 for stopping the heating means 2 when the time timed by the timing means 6 becomes larger than a fixed rate of a value of the memory means 7, an ON-OFF means 5 for electrifying the heating means 2 for a predetermined time, redriving the same after a second predetermined time and then driving the timing means 6 and a heating starting means 9 for driving the ON-OFF means 5.

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 heating and retaining the temperature of a liquid contained in a container.

[0002]

2. Description of the Related Art Conventionally, in this kind of electric water heater, a heating means for heating the liquid in the container is brought into contact with a cylindrical container having a bottom, and a temperature detecting means brought into contact with the container controls the temperature in the container. Detect. When the heating start means detects the start of heating, the heating means is driven by the energizing means, the storage means stores the time during which the first predetermined temperature width rises measured by the timing means, and then the boiling detection means measures the time. When the time measured by the means exceeds a certain ratio of the value of the storage means, the heating means is stopped to detect boiling.

[0003]

However, in such a conventional structure, there is a possibility that boiling may be erroneously detected depending on the temperature of the hot water at the start of heating, and as a means for solving the problem, Japanese Patent Laid-Open No. 3-4815. Is disclosed.

Further, for example, when a container containing a sufficient amount of water is gradually cooled to a heat retention temperature, hot water having a lowered temperature accumulates at the bottom of the container, causing a temperature difference from the upper layer of the hot water. When reheated in this state, convection centered on the bottom heated by the heating element continues for a while, and eventually changes to convection to the upper layer. At the time of convection centering on this bottom, it is as if a small amount of hot water is being heated, and the temperature curve is very steep as shown in Fig. 8 (a). Therefore, if the short time measured at the steep portion of this temperature curve is used as a reference, boiling will be erroneously detected when convection becomes complete. In particular, this factor becomes even more serious due to the increase in capacity, which has been increasing in weight lately, or the function of performing natural cooling to a heat retention temperature of 85 ° C. or 70 ° C.

In another example, the boiling detection operation unconditionally measures the time until the temperature rises to a predetermined value after the reference value is created. Therefore, as shown in FIG. When water is added to the water temperature, the water temperature decreases and rises again, but since the time is measured without considering it, the time measurement time becomes larger than a certain percentage of the reference value, and at that point The boiling is detected.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to detect the correct boiling of the liquid in the container regardless of the volume and the heat retention temperature.

[0007]

In order to achieve the above object, the present invention provides a container for containing a liquid, a temperature detecting means for detecting the temperature of the liquid in the container, and a heating means for heating the liquid in the container. And an energizing means for energizing the heating means, a time keeping means for keeping and clearing an increasing time for each first predetermined temperature width, and a time for increasing the first predetermined temperature width measured by the time keeping means. Storage means, a boiling detection means for stopping the heating means when the time measured by the time measuring means exceeds a certain ratio of the value of the storage means, and the heating means is energized for a first predetermined time, It is provided with an on / off means for re-driving after a predetermined time of 2 and thereafter for driving the timing means, and a heating start means for driving the on / off means.

Further, the temperature detecting means includes a decrease detecting means for re-driving the on / off means when the second predetermined temperature width decrease is detected.

Further, when the temperature detected by the temperature detecting means when the heating is started by the heating starting means is higher than a predetermined temperature, the time measuring means is driven, and when the temperature is low, the on / off means is driven.

[0010]

According to the present invention, in the above structure, the energizing means is turned on and off for a predetermined time to reduce the difference in water temperature in the container at the start of boiling water, and the convection is made constant, and then a reference value is created to stabilize boiling. Detection can be performed.

Further, when comparing the reference value with the clocking time after the reference value has already been created, even if water is added and there is no temperature rise and the clocking time increases, the reference value is set again when it stabilizes. Can be recreated.

Further, since the heating means is not turned on and off when the temperature at which the boiling water starts is high, a stable reference value can be created.

[0013]

【Example】

(Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to FIG.
Will be described with reference to.

FIG. 1 is a block diagram of an electric water heater according to a first embodiment of the present invention, in which 1 is a container for containing a liquid, 2 is heating means for contacting the container 1 and heating the liquid in the container 1,
Reference numeral 3 is a temperature detecting means for contacting the container 1 and detecting the temperature of the liquid in the container 1, and 4 is an energizing means for energizing the heating means 2.

Reference numeral 9 is a heating starting means for forcibly starting the boiling or automatically starting the boiling when the temperature becomes lower than a certain value.

Reference numeral 5 is an on / off means, 6 is a time counting means, 7 is a storage means, and 8 is a boiling detection means.
When the heating start signal of the heating start means 9 is input, the energization means 4 is energized for a first predetermined time (10 seconds in this embodiment) and then for a second predetermined time (1 time in this embodiment).
The energizing means 4 is turned off for 0 seconds. When the second predetermined time has elapsed, the energizing means 4 is re-driven, and the time counting means 6 starts time counting. The time measuring means 6 continues to measure the time during which the first predetermined temperature range (0.5 ° C. unit in this embodiment) rises, and stores the first time measured (hereinafter referred to as a reference value) in the storage means 7. . When the storage means 7 stores the reference value, the boiling detection means 8 compares a fixed multiple of this reference value (three times in this embodiment) with the 0.5 ° C. rise time measured by the clock means 6. The energizing means 4 is configured to stop energization when the time measured by the time measuring means 6 increases.

FIG. 2 is a circuit diagram of the electric water heater according to the first embodiment of the present invention. In FIG. 2, reference numeral 12 is an AC power supply. The heating means 2 is composed of a first heating element 2a that heats the liquid in the container and a second heating element 2b that has a smaller heating power than the first heating element 2a and that heats and keeps the temperature of the liquid in the container. . The energizing means 4 is a relay contact 4a, 4 connected in series with each heating element of the heating means 2 and the AC power source 12.
b, and relay coils 4c and 4d for controlling the relay contacts 4a and 4b.
A current is passed through d to close the relay contacts 4a and 4b. The temperature detecting means 3 is composed of a temperature sensitive element 3a for converting temperature into a resistance value and an AD converter 3b for converting the value of the temperature sensitive element 3a into a binary code. Reference numeral 9 is a part of the heating starting means, which is composed of a switch for forcibly starting the boiling of water. Reference numeral 13 is a microcomputer (hereinafter abbreviated as a microcomputer).

FIG. 3 shows a microcomputer 1 according to the first embodiment of the present invention.
3 shows a flow chart of a control part during boiling water of the program stored in FIG.

When it is detected that the temperature is forcibly or lower than a specific temperature during heat retention, the heating means 2 is turned on (step 1). After that, the heating means 2 is unconditionally waited for the time to turn on (step 2), and when the time to turn on elapses, the heating means 2 is turned off (step 3) and the time to turn off unconditionally elapses. The heating means 2 is turned on again after a lapse of the turning-off time (step 4), the time-keeping means 6 is cleared (step 5), and the time for increasing the temperature by 0.5 ° C. is measured (step 6, 7). When a 0.5 ° C. rise is detected in step 7, the value of the clock means 6 at that time is stored in the storage means 7 (step 8).

Next, in steps 9 to 12, the time measuring means 6 measures the time during which the temperature rises by 0.5 ° C. to 0.5 ° C.
When the temperature rises, the measured value is cleared, and the time to rise 0.5 ° C again starts to be measured. During that time, the value three times the time stored in the storage means 7 is continuously compared with the time during which the timekeeping means 6 is counting, and when the value of the timekeeping means 6 becomes large, the heating means 2 is regarded as boiling. Turn off (Step 1
3) It is structured.

As described above, according to the first embodiment, the boiling water is not erroneously set to the reference value for detecting a short boiling when the temperature difference between the upper and lower water is generated at the start of the water boiling. It becomes possible.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIGS. 4 and 5. The first
The same components as those described in the above embodiment are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 4 is a block diagram of an electric water heater according to a second embodiment of the present invention. The difference from the first embodiment is that a drop detecting means 10 is added. When the decrease detecting means 10 detects that the temperature detecting means 3 has decreased more than a second predetermined temperature range (3 ° C. in the present embodiment), the operation of the clocking means 6, the storing means 7 and the boiling detecting means 8 is performed. It is configured to be stopped and to be restarted from the on / off means 5.

FIG. 5 shows a flow chart of the control portion during the boiling of the program stored in the microcomputer 13 of the second embodiment, and the operation will be described with this.

As in the case of FIG. 3, when the boiling of water is started, the heating means 2 is turned on / off in steps 21 to 24.

When the heating means 2 is restarted in step 25, the timekeeping means 6 is cleared and the time for which the temperature rises by 0.5 ° C. is measured (steps 27 and 28). When the temperature detecting means 3 detects a temperature decrease of 3 ° C. or more during this period, the operation is restarted from step 21 (step 26). When a 0.5 ° C. rise is detected in step 28, the value of the clock means 6 at that time is stored in the storage means 7 (step 29).

Next, in steps 30 to 34, the time measuring means 6 measures the time during which the temperature rises by 0.5.degree.
When the temperature rises by 0 ° C, the measured value is cleared, and the time when the temperature rises by 0.5 ° C is restarted. During that time, the value three times the time stored in the storage means 7 is continuously compared with the time during which the timekeeping means 6 is counting, and when the value of the timekeeping means 6 becomes large, the heating means 2 is regarded as boiling. It is configured to be turned off (step 35). In the meantime, if the temperature detecting means 3 detects a temperature decrease of 3 ° C. or more, the operation is restarted from step 21 (step 31).

As described above, according to the second embodiment, it is possible to adopt a configuration in which the boiling point is not accidentally boiled due to the temperature drop due to the addition of water during boiling.

(Embodiment 3) A third embodiment of the present invention will be described with reference to FIGS. 6 and 7. The second
The same components as those described in the above embodiment are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 6 is a block diagram of an electric water heater according to a third embodiment of the present invention, which differs from the second embodiment in that a comparison means 11 is added. When the comparison means 11 inputs the heating start signal of the heating start means 9, when the temperature of the temperature detection means 3 is equal to or higher than a predetermined temperature (92 ° C. in the present embodiment) at that time, the timer means 6 is set to a temperature lower than the predetermined temperature. In this case, the on / off means 5 is driven respectively.

FIG. 7 shows a flow chart of the control part during the water heating of the program stored in the microcomputer 13 of the third embodiment, and the operation will be described by the dust.

When it is detected that the temperature is forcibly or lower than a certain temperature during heat retention, the temperature detecting means 3 determines whether the temperature is lower than a predetermined temperature (92 ° C. in this embodiment) or higher ( Step 41), when the temperature is lower than the predetermined temperature, FIG.
Similarly to the above, the heating means is turned on and off in steps 42 to 45.

When the temperature exceeds the predetermined temperature in step 41, or when the heating means is turned on and off, the heating means 2 is driven in step 46 to clear the timekeeping means 6 and increase the temperature by 0.5 ° C. Is measured (steps 48 and 49). During this time, the temperature detecting means 3
When the temperature decrease of ℃ or more is detected, the process returns to step 41 and the re-operation is started depending on the temperature at that time being higher than or lower than the predetermined temperature (step 47). Further, when the increase of 0.5 ° C. is detected in step 49, the value of the time measuring means 6 at that time is stored in the storage means 7 (step 5).
0).

Next, in steps 51 to 54, the time measuring means 6 measures the time during which the temperature rises by 0.5 ° C. to 0.5
When the temperature rises by 0 ° C, the measured value is cleared, and the time when the temperature rises by 0.5 ° C is restarted. During that time, the value three times the time stored in the storage means 7 is continuously compared with the time during which the timekeeping means 6 is counting, and when the value of the timekeeping means 6 becomes large, it is regarded as boiling and the heating means 2 is turned off. Allow (Step 5
6) It is structured. During this time, if the temperature detecting means 3 detects a temperature decrease of 3 ° C. or more, step 4
The re-operation is started from 1 (Step 5
2).

As described above, according to the third embodiment, when the temperature at the start of boiling water is high, the reference value for boiling detection can be created without performing on / off heating.

In this embodiment, the heating means and the heat retaining means are collectively set as the heating means and are turned on at the same time, but the same effect can be obtained by using only the heating element for heating.

[0037]

As is apparent from the description of the above embodiments, the present invention turns on and off the heating means for a predetermined time at the start of boiling water to stabilize the convection, so that the reference value for boiling detection can be stably created. It is possible to detect boiling properly.

Further, even if water is added in the course of boiling water, since the water temperature is stabilized and the reference value for boiling detection is recreated, boiling can be detected more reliably.

When the boiling water start temperature is high, the heating means is not turned on and off, so that a stable boiling detection reference value can be created and stable boiling detection can be performed.

From the above, it is possible to provide a high-quality electric water heater that is easy to use.

[Brief description of drawings]

FIG. 1 is a block diagram of an electric water heater according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram of the electric water heater.

FIG. 3 is a flowchart showing the operation of the electric water heater.

FIG. 4 is a block diagram of an electric water heater according to a second embodiment of the present invention.

FIG. 5 is a flowchart showing the operation of the electric water heater.

FIG. 6 is a block diagram of an electric water heater according to a third embodiment of the present invention.

FIG. 7 is a flowchart showing the operation of the electric water heater.

FIG. 8 (a) is an explanatory diagram showing the relationship between the sensor of the electric water heater and the water temperature. FIG. 8 (b) is an explanatory diagram showing the water temperature when water is added to the water heater of the electric water heater.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Container 2 Heating means 3 Temperature detecting means 4 Energizing means 5 On / off means 6 Timing means 7 Storage means 8 Boiling detection means 9 Heating start means 10 Decrease detection means 11 Comparison means

Claims (3)

[Claims] 1. A container for containing a liquid, a temperature detecting means for detecting the temperature of the liquid in the container, a heating means for heating the liquid in the container, and an energizing means for energizing the heating means.
Time keeping means for keeping and clearing the rising time for each first predetermined temperature range, storage means for storing the first rising time for the first predetermined temperature range kept by the time measuring means, and for keeping time by the time keeping means The boiling detection means for stopping the heating means when the remaining time becomes larger than a certain ratio of the value of the storage means, and the heating means is energized for a first predetermined time, and is re-driven after a second predetermined time, and then the An electric water heater equipped with an on / off means for driving a clocking means and a heating start means for driving the on / off means. 2. The electric water heater according to claim 1, further comprising: drop detecting means for re-driving the on / off means when the temperature detecting means detects a decrease in the second predetermined temperature range. 3. A comparison means for driving the clocking means when the temperature detected by the temperature detecting means when the heating is started by the heating starting means is higher than a predetermined temperature, and the on-off means when the temperature is lower than the predetermined temperature. Or the electric water heater described in 2.