JP3148916B2 - Electric water heater - Google Patents

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 keeping water contained in a container.

[0002]

2. Description of the Related Art In recent years, in electric water heaters,
As disclosed in Japanese Patent Application Laid-Open No. 17813/1992, after water is boiled, the temperature is kept as close to the boiling point as possible.

FIG. 6 shows a conventional electric water heater.
This will be described with reference to FIG. 6 is a partial cross-sectional view of a conventional electric water heater, FIG. 7 is a circuit configuration diagram, and FIG. 8 is an explanatory diagram of boiling detection.

[0006] In FIG. 6, a container 2 having an upper surface opening is provided in a main body 1, and lids 3 for covering an upper portion of the container 2 are arranged. Further, a heater 4 as heating means for heating water in the container 2, a heater 5 as heating means for heating and keeping water, and a temperature sensor 6 for detecting the temperature of water inside the container 2 are arranged downward. Are located. And the temperature sensor 6
Is input to the temperature detecting means 7 to detect the water temperature. The energization of the heating heater 4 and the heat retaining heater 5 is controlled by a heating energizing means 8 and a heat retaining energizing means 9, respectively. The boiling detecting means 10 outputs the temperature rising rate from the temperature detecting means 7 to the heating / warming control means 16 when the temperature rise rate becomes lower than a predetermined value from the temperature rise rate when the water temperature is low. The re-boiling setting means 13 is for making settings when boiling is performed again in the heat-retaining state. The re-boiling setting means 13 is constituted by, for example, a push switch or the like, and is input to the heating / heat keeping control means 16. The heat retaining temperature setting means 14 sets the heat retaining temperature, and is input to the heating energizing means 8. The heating and keeping control means 16 outputs to the display means 15, and the display means 15 displays a boiling LED 15 a that indicates that the water is being heated, and a high-temperature keeping LED 15 b that indicates that the temperature is kept at about 95 ° C. It is composed of an 85-warming LED 15c for displaying that the temperature is maintained at about 85 ° C, and a 70-warming LED 15d for displaying that the temperature is maintained at about 70 ° C.

When the water in the container 2 is heated for the first time, the heating and keeping control means 16 controls the heating heater 4 through the heating and supplying means 8 and 9 by the output of the temperature detecting means 7.
And the heater 5 is energized and heated. Boiling detection means 1
When the detection of boiling is input by 0, energization control of the heat retaining heater 5 is performed so that the temperature is maintained at the temperature set by the heat retaining temperature setting means 14. When the re-boiling setting means 13 is set, the heating heater 4 and the heat keeping heater 5 are controlled to conduct electricity again through the heating means 8 and the heat keeping means 9 based on the temperature data from the temperature detecting means 7, and the water in the container 2 boils. Heat until

The overall operation of the electric water heater constructed as described above will be described with reference to FIGS. 7 and 8. In FIG. 7, a microcomputer 17 controls a relay as the heating and energizing means 8 and a triac as the thermal insulation and energizing means 9 to determine the amount of electric power to the heater 4 and the thermal insulation heater 5. When the water is boiled, the microcomputer 17 operates the heating and energizing means 8 and the heat retaining and energizing means 9 to energize the heating heater 4 and the heat retaining heater 5. After the boiling, when the water is to be kept warm, the microcomputer 17 activates the heat keeping energizing means 9 to turn on the heat keeping heater 5.

On the other hand, the resistance value of the temperature sensor 6 mounted in pressure contact with the container 2 changes according to the temperature of the water in the container 2. Then, a resistor 7 connected in series with the temperature sensor 6
The ratio of the resistance value to “a” changes and is input as a voltage change to the A / D converter 7b. After being converted into a digital value by the A / D converter 7b, it is input to the microcomputer 17 as temperature data. The voltage determined by the resistors 7c and 7d is also input to the A / D converter 7b, and the temperature at the time of high temperature keeping (about 95 ° C.)
Is determined. The voltage determined by the resistors 7e and 7f determines the temperature (about 85 ° C.) at the time of keeping the temperature at 85. The voltage determined by the resistors 7g and 7h determines the temperature (about 70 ° C.) when the temperature is kept at 70. Further, the heat retaining temperature setting means 14
, And a reboiler switch as the reboil setting means 13 are connected to the microcomputer 17 as inputs and the display means 15 is connected to the output of the microcomputer 17.

Referring to FIG. 8, a method for detecting boiling will be described.
After energization of the heating heater 4 and the heat retaining heater 5, the time (Δta) when the temperature data from the temperature sensor 6 rises by unit temperature (Δθ is about 0.5 ° C.) is measured, and the temperature of the water rises during that time. When the temperature is constant, Δta increases (Δtb) when the boiling point (θ1) is approached. When Δtb is longer than Δta by a predetermined magnification or more, the microcomputer 1 determines that the water has boiled.
7 detects.

After the boiling is detected, the temperature sensor 6
The temperature is maintained at the high temperature temperature (about 95 ° C.) while comparing the resistance value ratio of the resistor 7a connected in series with the resistor 7a and the resistance value ratio of the resistors 7c and 7d which determine the high temperature heat retaining temperature. Then, the heat retaining and energizing means 9 is operated.

[0010]

However, in the above-described conventional configuration, the heat retention temperature is determined by the temperature sensor 6 and the resistor 7a connected in series with the temperature sensor 6, so that the heat retention temperature is always constant at the set temperature. If the heat retention temperature is raised and the temperature is kept close to the boiling point, the boiling point is lowered when the atmospheric pressure is low, such as in a high altitude, so that the boiling may be continued. Therefore, there was a problem that the hot water could not be provided because the heat retention temperature could not be raised.

An object of the present invention is to solve the above-mentioned conventional problems, and it is an object of the present invention to maintain the temperature at a temperature closer to the boiling point regardless of the atmospheric pressure.

[0012]

Means for Solving the Problems To achieve the above object, a first object of the present invention is to control the heat-retaining means so that the heat-retaining means performs intermittent energization for a predetermined time after the detection of boiling. The apparatus is provided with temperature determining means for inputting a detected temperature from the post-temperature detecting means, and control means for controlling the heat-retaining energizing means so as to keep the temperature at a predetermined temperature lower than the temperature of the temperature determining means.

Further, a second object of the present invention is to control the heat-retaining means so that the heat-retaining means performs intermittent current supply after the boiling detection until the temperature change rate from the temperature detecting means becomes a predetermined value or less, It comprises temperature determining means for inputting the detected temperature from the temperature detecting means at that time, and control means for controlling the heat-retaining energizing means so as to maintain the temperature at a predetermined temperature lower than the temperature of the temperature determining means. is there.

Further, a third object of the present invention is to control the heat-retaining and energizing means so that the heat-retaining means performs intermittent energization immediately after the detection of boiling, and the passage time per unit temperature of the temperature detected by the temperature detecting means. A temperature determining means for inputting a temperature detected by the temperature detecting means when the ratio becomes equal to or less than a predetermined ratio with respect to a passage time per unit temperature after a predetermined time has elapsed after the detection of boiling; It is provided with control means for controlling the heat-retaining energizing means so as to keep the temperature at a low temperature.

[0015]

According to the present invention, it is possible to stably input the temperature detected by the temperature sensor when the water boils by continuously supplying electricity even after the water boils. By keeping the temperature at a temperature several degrees lower than the detected temperature, it is possible to set the temperature to be a predetermined temperature lower than the boiling point of water, instead of a predetermined constant temperature. Therefore, it is possible to keep the heat without boiling even at high altitude, and it is also possible to keep the heat at a temperature close to the boiling point, for example, the boiling point minus 2 ° C.
Hot water with a higher temperature can be provided.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, first to third embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a partial cross-sectional view of the first to third embodiments of the present invention. The circuit diagram is almost the same as that of the conventional example (only the resistors 7c and 7d are not provided). Because of the differences, only the flowcharts for selecting the high-temperature insulation are shown in FIGS. FIG. 5 is a graph showing the operation at the time of boiling detection. 1 and 5, the same parts as those in FIGS. 6 and 8 described above are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 1, the difference between the first to third embodiments is the operation of the temperature determining means 11. (Embodiment 1) A first embodiment of the present invention will be described with reference to FIGS. In FIG. 1, after the temperature determination means 11 detects boiling by the boiling detection means 10, it outputs to the control means 12 a signal for controlling the heat insulation energizing means 9 so that the heat insulation means 5 performs intermittent energization for a predetermined time. The detected temperature from the subsequent temperature detecting means 7 is input. Control means 12
In the case of water heating, the same operation as that of the conventional example is performed, and at the time of keeping the temperature, the heat-retaining energizing means 9 is controlled to keep the temperature at a temperature lower than the temperature determined by the temperature determining means 11 by a predetermined temperature.

FIG. 2 is a flowchart of the first embodiment of the present invention. After the power is turned on, in step 1, the heating heater 4 and the heat retaining heater 5 are energized to start heating. And
The time when the unit temperature rises is measured (ΔTn), and the time when the previous unit temperature rise (ΔTn−
Compare with 1). When ΔTn <ΔTn−1, it is determined that the temperature has not risen, and the process returns to step 1. ΔTn ≧ ΔTn-1
In step 3, it is checked in step 3 whether the measurement has been performed four times, and the process returns to step 1 until the measurement has been performed four times. After measuring four times, in step 4, add from ΔT2 to ΔT4 (ΔT = ΔT2 + ΔT3 +
ΔT4). Then, the time when the unit temperature rises is measured in step 5 (ΔTa), and in step 6, ΔTa and ΔT are compared. When ΔTa <ΔT, the process returns to step 5. Δ
When Ta ≧ ΔT, boiling is detected in step 7. When the boiling is detected, intermittent energization (for example, ON for 2 seconds, OFF for 1 second) is performed only for the heat retaining heater 5 for a predetermined time in Step 8. When the temperature data of the temperature sensor 6 becomes stable, the temperature is inputted in step 9 (θ4), and in step 10, the temperature is kept so that the temperature of the temperature sensor 6 becomes several degrees lower than the temperature (θ4) (θ4-Δθ4). .

(Embodiment 2) In a second embodiment of the present invention,
The temperature determining means 11 detects the boiling by the boiling detecting means 10 and then keeps the heat maintaining means 5 so that the temperature maintaining means 5 performs the intermittent current supply until the temperature change rate from the temperature detecting means 7 becomes a predetermined value or less.
Is output to the control means 12, and the detected temperature from the temperature detecting means 7 when the temperature change rate becomes a predetermined value or less is input.

FIG. 3 is a flowchart of the second embodiment of the present invention. The same steps as those in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted. After the boiling is detected in step 7, only the heat retaining heater 5 is intermittently energized in step 11 (for example, for 2 seconds,
(One second off), and the transit time when the predetermined temperature is increased in step 12 is measured (ΔTm). Δ in step 13
A comparison is made as to whether Tm is larger than a predetermined value. If ΔTm <predetermined value, the process returns to step 12, and if ΔTm ≧ predetermined value, it is determined that the temperature data of the temperature sensor 6 is stable. (Θ4), and in step 10, the temperature sensor 6 detects a temperature (θ4−Δ4) that is several degrees lower than the temperature (θ4).
Keep the temperature so that θ4).

(Embodiment 3) In a third embodiment of the present invention,
After detecting the boiling by the boiling detecting means 10, the temperature determining means 11 outputs to the control means 12 a signal for controlling the heat-retaining means 9 so that the heat-retaining means 5 performs the intermittent current supply, and outputs the signal to the temperature detecting means 7.
The detection temperature of the temperature detection means 7 is input when the passing time per unit temperature of the detected temperature becomes equal to or less than a certain ratio with respect to the passing time per unit temperature after the elapse of a predetermined time after the detection of boiling.

FIG. 4 is a flowchart of the third embodiment of the present invention. The same steps as those in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted. After the boiling is detected in step 7, only the heat retaining heater 5 is intermittently energized in step 14 (for example, for 2 seconds,
(1 second off), and waits for a predetermined time in step 15.
Then, the passage time when increasing the predetermined temperature is measured in step 16 (ΔTm), and after waiting for a certain time in step 17, the passage time when increasing the predetermined temperature is measured in step 18 (ΔTL). ΔTL at step 19
Is greater than or equal to the predetermined magnification of ΔTm, it is determined that the temperature data of the temperature sensor 6 is stable, and the temperature is input at step 9 (θ4), and at step 10 the temperature sensor 6 The temperature is kept so as to be lower by several degrees Celsius (θ4−Δθ4). If ΔTL is equal to or smaller than the predetermined magnification of ΔTm, the process returns to step S17.

In FIG. 5, the temperature of the temperature sensor 6 when the water reaches the boiling point varies depending on the amount of water. After the boiling is detected, in the first to third embodiments of the present invention, the temperature of the temperature sensor 6 when the water is boiling is kept constant by the constant temperature difference by changing the temperature of the temperature sensor 6 when the water is boiling. (Δθ5). Then, by controlling the temperature sensor 6 at a temperature (Δθ4) several degrees lower than the temperature (θ4) of the temperature sensor 6 when the water is boiling, the hot water is kept at a temperature (Δθ4) several degrees lower than the boiling temperature. can do.

[0024]

As is apparent from the above description, according to the present invention, the heater and the heat retaining heater are energized based on the temperature information from the temperature sensor, and the heat insulating heater is continuously energized for a predetermined time after the water boils. By stabilizing the temperature detected by the temperature sensor when water boils, and keeping it at a temperature several degrees lower than the stable detected temperature, it is possible to keep the temperature without boiling even at high altitudes, and to maintain the boiling point. For example, a warming temperature of a boiling point minus 2 ° C. becomes possible, so that hot water having a higher temperature can be provided.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of an electric water heater according to first to third embodiments of the present invention.

FIG. 2 is a flowchart showing the operation of the electric water heater of the first embodiment.

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

FIG. 4 is a flowchart showing the operation of the electric water heater of the third embodiment.

FIG. 5 (a) is a graph showing the boiling operation of the electric water heater when the amount of water is large, and FIG. 5 (b) is a graph showing the boiling operation of the electric water heater when the amount of water is small.

FIG. 6 is a partial sectional view of a conventional electric water heater.

FIG. 7 is a circuit configuration diagram of the electric water heater.

FIG. 8A is a graph showing a boiling operation of the electric water heater when the amount of water is large, and FIG. 8B is a graph showing a boiling operation of the electric water heater when the amount of water is small.

[Explanation of symbols]

 2 Container 4 Heater (heating means) 5 Heating heater (heating means) 6 Temperature sensor 7 Temperature detection means 8 Heating means 9 Heating means 10 Boiling detection means 11 Temperature determination means 12 Control means

Claims (3)

(57) [Claims] 1. A container for storing a liquid, a heating unit for heating the liquid in the container, a heating unit for energizing the heating unit, and a heat retaining unit for heating and keeping the temperature of the liquid in the container. And a heat-retaining energizing means for energizing the heat-retaining means, and a temperature detecting means for detecting a liquid temperature in the container,
Boiling detection means for detecting that the liquid in the container has boiled by the output of the temperature detection means, and after the boiling detection, controlling the heat insulation energizing means so that the heat insulation means performs intermittent energization for a predetermined time, and for a predetermined time An electric water heater further comprising a temperature determining means for inputting a detected temperature from the temperature detecting means, and a control means for controlling the heat-retaining energizing means to keep the temperature at a predetermined temperature lower than the temperature of the temperature determining means. 2. A container for accommodating a liquid, a heating unit for heating the liquid in the container, a heating unit for energizing the heating unit, and a heating unit for heating and maintaining the temperature of the liquid in the container. And a heat-retaining energizing means for energizing the heat-retaining means, and a temperature detecting means for detecting a liquid temperature in the container,
Boiling detection means for detecting that the liquid in the container has boiled by the output of the temperature detection means; and intermittent energization of the heat retention means until the temperature change rate from the temperature detection means becomes a predetermined value or less after the detection of the boiling. Controlling the heat-retaining energizing means so as to perform, and a temperature determining means for inputting a detected temperature from the temperature detecting means at that time, and a heat-retaining energizing means for maintaining the temperature at a predetermined temperature lower than the temperature of the temperature determining means. An electric water heater having a control means for controlling. 3. A container for accommodating a liquid, a heating unit for heating the liquid in the container, a heating unit for energizing the heating unit, and a heating unit for heating and maintaining the temperature of the liquid in the container. And a heat-retaining energizing means for energizing the heat-retaining means, and a temperature detecting means for detecting a liquid temperature in the container,
Boiling detection means for detecting that the liquid in the container has boiled based on the output of the temperature detection means, and controlling the heat insulation energization means so that the heat insulation means performs intermittent energization immediately after the boiling detection, and the temperature detection means Temperature determination means for inputting the detection temperature of the temperature detection means when the passage time per unit temperature of the detected temperature is less than or equal to a certain ratio with respect to the passage time per unit temperature after a predetermined time has elapsed after the detection of boiling. An electric water heater having control means for controlling the heat-retaining energizing means so as to keep the temperature at a predetermined temperature lower than the temperature of the temperature determining means.