JPH09140584A - Electric water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enlarge the sectional area of a heater so as to prevent breakage of a wire and to restrain water boiling noise during heat insulation by providing a heat insulation intermittent current applying means for intermittently applying a current to a heat insulating heater for keeping temperature at a designated degree during heat insulation. SOLUTION: When a heat insulation intermittent current applying means 15 enters a heat insulation mode, according to a signal from a temperature sensor 6, it is converted to the temperature information by a temperature detecting means 7, and if the temperature is below a designated heat insulation temperature, a current is applied intermittently to a heat insulation heater 5 to heat water, and if above the heat insulation temperature, the current application to the heat insulating heater 5 is stopped. The intermittent current application is performed in such a manner that first during a first designated time (e.g. three seconds), a current is applied to the heat insulating heater 5. In the lapse of the first designated time, the current application to the heat insulating heater 5 is stopped to be on standby during the elapse of a second designated time (e.g. 12 seconds). In the lapse of the second designated time, again the heat insulation temperature is examined to repeat the above operation. Accordingly, the electric energy during current application for heat insulation can be reduced, so that the power of the heat insulating heater can be increased to the permissible limit of water boiling noise.

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 A conventional electric water heater will be described below. FIG. 6 is a cross-sectional configuration diagram of a main part of a conventional electric water heater, FIG. 7 is an explanatory diagram of boiling detection, and FIG. 8 is a circuit configuration diagram.

In FIG. 6, a container 2 having an upper surface opening is provided in a water heater main body container 1, and a lid 3 for covering the opening is provided on an upper portion of the container 2. Further, the heater 4 for heating the water inside the container 2, the heat retaining heater 5 for retaining the heat, and the container 2
A temperature sensor 6 for detecting the temperature of water inside the container is provided at the bottom of the container, and the heater 4 is energized and controlled by the heating energizing means 8. The signal from the temperature sensor 6 is input to the temperature detecting means 7 to detect the water temperature. The boiling detection means 9 outputs a signal to the control means 10 when it detects that the water has boiled based on the temperature information from the temperature detection means 7.
The control means 10 enters the boiling mode when the water temperature is low, and energizes the heater 4 to raise the water temperature. When the water temperature rises and the boiling detection means 9 detects boiling, the notification means 11 notifies boiling and the control means 10 shifts to the heat retention mode. In the heat retention mode, the signal from the temperature sensor 6 is converted into temperature information by the temperature detection means 7, and when the temperature is below a predetermined heat retention temperature, the control means 10 causes the heat retention energization means 12 to turn on the heat retention heater 5 (about 75 w). Electricity is supplied to heat the water, and when the temperature is equal to or higher than the predetermined heat retention temperature, the power supply to the heat retention heater 5 is stopped.
When the reboil setting means 13 sets reboil, the control means 10
Can enter boiling mode and boil water again.

The boiling detection method of the boiling detection means 9 will be described with reference to FIG. In FIG. 7, the temperature of the temperature sensor rises at a substantially constant rate until it approaches the boiling point, and the temperature rise rate decreases when it approaches the boiling point. The time per unit temperature rise Δθ when the temperature rises at a constant rate is ΔT1, ΔT2, Δ
When T3 is set and the time per unit temperature increase Δθ near the boiling point is set to ΔTn, it is detected that the water has boiled when the following equation is satisfied.

ΔT1 + ΔT2 + ΔT3 <ΔTn The entire operation of the electric water heater constructed as described above will be described with reference to FIG. The resistance value of the temperature sensor 6 attached to the container 2 under pressure changes according to the temperature change of the water in the container 2. Then, the resistance value ratio between the temperature sensor 6 and the resistor 7a connected in series changes, and A / D
The voltage change is input to the converter 7b, and the A / D converter 7
After being converted into a digital value by b, the microcomputer 20
Input as temperature information. The voltage determined by the resistors 7c and 7d is also input to the A / D converter 7b to determine the heat retention temperature. When heating water in the boiling mode, the microcomputer 20 activates the relay contact 8b of the relay 8a to energize the heater 4. After the boiling detection, when the temperature of the water is lower than the heat retaining temperature after entering the heat retaining mode, the microcomputer 20 operates the thyristor 12a to energize the heat retaining heater 5. When the water temperature is higher than the heat retention temperature, the microcomputer 20 operates in the thyristor 12a.
Is turned off, and the power supply to the heat retention heater 5 is stopped.

A switch 13 as reboil setting means is input to the microcomputer 20,
The buzzer 11 as a notification means and the display means 14 are output. When the switch 13 is pushed, the boiling mode is entered, and when the boiling is detected in the boiling mode, the buzzer 11 gives an alarm. The display means 14 has a boiling LED 14a and a heat retaining LED 14b. The boiling LED 14a is lit in the boiling mode and the heat retaining LED 14b is lit in the heat retaining mode.

[0007]

In the electric water heater having the above-mentioned conventional configuration, the electric power of the heat-retaining heater is as small as 75w and the installation space is structurally limited. I had to reduce the cross-sectional area. Therefore, the heater is easily broken and is difficult to manufacture. However, in order to solve the problem, if the electric power of the heat retention heater is simply increased, there is a problem that the boiling water noise is increased.

The present invention solves the above-mentioned conventional problems. A first object of the present invention is to increase the electric power of the warming heater to increase the cross-sectional area of the heater and to prevent the heater from breaking, while suppressing the noise of boiling water during warming. It is to provide an electric water heater that is as small as possible. A second object is, in addition to the achievement of the first object, to prevent the flicker of the lighting which occurs when the electric water heater and the lighting equipment of the present invention are connected to the same power supply circuit.

[0009]

In order to solve the conventional problems, the means for solving the problems of the present invention is to keep warm at a temperature lower than the warm temperature by keeping the warm heater intermittently energized to keep warm at a predetermined warm temperature. It is configured by including a heat insulation intermittent energizing means.

Further, the means for solving the problem for achieving the second object is constituted so that the intermittent energization period of the heat retention intermittent energizing means is several seconds or more. According to the present invention, it is possible to obtain an electric water heater that is free from disconnection of the heat retention heater and is easy to manufacture, and at the same time, it is possible to prevent flicker of illumination during use.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention is a container for containing a liquid, a heat retaining heater for retaining the temperature of the liquid in the container, and a temperature detecting means for detecting the temperature of the liquid in the container. In order to keep the temperature at a predetermined temperature during heat retention, when the temperature falls below a predetermined temperature, the heat insulation heater is intermittently energized to heat, and when the temperature exceeds the heat retention temperature, the current is stopped and the temperature is maintained. This is an electric water heater equipped with a current-carrying means.By heating the heat-retaining heater by intermittently energizing it during heat retention, the amount of power during heat-retention energization can be reduced. It can be increased to the limit. Therefore, since the cross-sectional area of the heating element can be set to be large, the heater can be easily handled during the manufacturing process and the heater can be free from disconnection.

The invention according to claim 2 is the electric water heater according to claim 1 in which the period of intermittent energization by the heat retention intermittent energizing means is several seconds or more, and the same electric power source as the electric water heater of the present invention is used. When a lighting device such as a fluorescent lamp connected to the circuit is connected and the heater of the present invention is energized, the load on the power supply circuit may increase, the terminal voltage may drop, and the illumination may become dark. Since the light is bright when the heater is not energized, the lighting repeats lighting and darkness by opening and closing the power supply to the heater. If this repetition of light and dark occurs continuously for a few seconds or less, it is perceived by the human eye as flicker of lighting, which is very uncomfortable. Therefore, by setting the power supply opening / closing cycle of the heating heater to several seconds or more, and opening / closing the heat insulation heater within the range where flicker is not recognized,
In addition to the first aspect, an electric water heater that does not affect lighting can be provided.

According to a third aspect of the present invention, there is provided the electric water heater according to the first aspect in which the heat insulation intermittent energizing means controls the phase of the heat insulation heater. The frequency is set so that the flicker of human eyes is not felt.

[0014]

【Example】

(Embodiment 1) Hereinafter, an embodiment of the invention described in claims 1 and 2 of the present invention will be described as Embodiment 1 with reference to the drawings. In FIG. 1, the same parts as those in FIG. 7 described above are designated by the same reference numerals and the description thereof is omitted.

In FIG. 1, when the heat retention intermittent energization means 15 enters the heat retention mode, the temperature detection means 7 converts the temperature information into a temperature information by a signal from the temperature sensor 6, and when the temperature is below a predetermined heat retention temperature, the heat retention is carried out. The heater 5 (for example, 300 w in one embodiment) is intermittently energized to heat the water, and when the temperature is higher than the heat retention temperature, the power supply to the heat retention heater 5 is stopped.

The circuit configuration diagram of the first embodiment is shown in FIG.
Although it is the same as that shown in FIG. 2, the operation flowchart of the microcomputer 20 at the time of heat retention is different, and the operation flowchart will be described next.

In FIG. 2, first, at step 100, the power source is energized, and at step 101, the water temperature is checked. If the water temperature is high, shift to the heat retention mode. When the water temperature is low (about 85 ℃
The following) turns on the boiling LED 14a in step 102, turns on the relay, and energizes the heater 4. Wait until it boils in step 103, then step 1
At 04, the boiling LED 14a is turned off, and the buzzer notifies
The relay is turned off to stop the energization of the heater 4 and shift to the heat retention mode. In the heat retention mode, the heat retention LED 14b is turned on in step 105, and it is checked in step 106 whether the temperature is equal to or higher than the heat retention temperature. If it is above, in step 107, the thyristor 15a is turned off to stop the power supply to the heat retention heater 5. In the following case, the thyristor 15a is turned on in step 108 to energize the heat retention heater 5. In step 109, the process waits until the first predetermined time (3 seconds in the embodiment) has elapsed. After the lapse of the first predetermined time, in step 110, the thyristor 15a is turned off and the power supply to the heat retention heater 5 is stopped. Then, in step 111, it waits until the second predetermined time (12 seconds as an example) has elapsed. When the second predetermined time has elapsed, the process proceeds to step 106.

(Embodiment 2) An embodiment according to claim 3 of the present invention will be described as Embodiment 2 with reference to the drawings. In FIGS. 3 and 5, the same parts as those in FIGS. 1 and 2 described above are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 3, the zero-cross input means 16 detects 0v (zero volt) of the commercial power source, and when the warming phase control means 17 energizes the warming heater 5, the signal is supplied to the commercial power source at a predetermined phase. Is to start.

In FIG. 4, resistors 16a, 16b, 1
6c and the capacitor 16d are the zero-cross input means 16. In the heat retention mode, the temperature sensor 6 and the resistor 7a
If the temperature information of the water determined by is equal to or lower than the heat retention temperature determined by the resistors 7c and 7d, the microcomputer 21 waits for the zero volt signal to be input from the zero cross input means 16. After the input, a predetermined phase (for example, a phase angle of 120 ° in one embodiment) elapses, and then the thyristor 17a is turned on. If the temperature is equal to or higher than the heat retention temperature, the microcomputer 21 turns off the thyristor 17a.

The operation flow chart of the microcomputer 21 of the second embodiment in the heat retention mode will be described below. The operation flowchart of the boiling mode is the same as that in FIG.

In FIG. 5, when the heat retention mode is entered, the heat retention LED 14b is turned on in step 112 and step 1
Check in step 13 whether the temperature is above the heat retention temperature. If it is above, the thyristor 17a is turned off in step 114 to stop the energization of the heat retention heater 5. If it is below, check in step 115 whether the commercial power supply has become 0v (zero volt), and
When (zero volt) is detected, in step 116, the process waits until the phase in which the thyristor 17a is turned on. When the phase to turn on is reached, the thyristor 17a is turned on at step 117, and the routine proceeds to step 113.

[0023]

As described above, according to the present invention, the amount of electric power during heat retention energization can be reduced by intermittently energizing the heat retention heater during heat retention. The area can be increased, handling during manufacturing can be facilitated, and breakage of the heater can be eliminated.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram of essential parts of an electric water heater according to a first embodiment of the present invention.

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

FIG. 3 is a partial cross-sectional configuration diagram of an electric water heater according to a second embodiment of the present invention.

FIG. 4A is a circuit configuration diagram of the electric water heater, and FIG. 4B is a thyristor energization waveform diagram of the electric water heater.

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

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

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

FIG. 8 is a circuit configuration diagram of the electric water heater.

[Explanation of symbols]

 2 container 4 heating heater 5 heat retention heater 6 temperature sensor 7 temperature detection means 8 heating energization means 9 boiling detection means 10 control means 11 notification means (buzzer) 13 reboil setting means (switch) 14 display means 15 heat retention intermittent energization means 16 zero cross Input means 17 Insulation phase control means

Claims (3)

[Claims] 1. A container for containing a liquid, a heat retaining heater for retaining the temperature of the liquid in the container, a temperature detecting means for detecting a temperature of the liquid in the container, and a predetermined heat retaining temperature for retaining a predetermined temperature. An electric water heater provided with a heat retention intermittent energizing means for intermittently energizing and heating the above-mentioned heat retention heater when the temperature becomes lower than a temperature, and stopping energization when the temperature exceeds the heat retention temperature. 2. The electric water heater according to claim 1, wherein a period of intermittent energization by the heat retention intermittent energizing means is set to several seconds or more. 3. The electric water heater according to claim 1, wherein the heat insulation intermittent energizing means controls the phase of the heat insulation heater.