JPH10197070A - Electric water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric water heater which can boil up hot water in a hot water storage tank even when hot water is used during the waiting time to the start of electric energization. SOLUTION: This electric water heater is provided with a heater 2 for boiling up hot water by electric power, a hot water storage tank 1 for storing hot water, a cold water temperature sensor 5 for detecting the temperature of water, residual hot water sensors 71 -73 for detecting temperature according to the reside of hot water, a boil up sensor 6 to detect boiling up temperature of hot water and a controller 8. This controller 8 calculated waiting time for boiling up hot water at the end of the midnight power period on a basis of the temperature of the residual hot water and the detected residue thereof to supply a midnight power as a specified time passes. But when the water temperature sensor 5 and/or the residual hot water sensors 71 -73 detect changes in temperature during the waiting time, the midnight power is immediately supplied to the heater 2 and the supply of the midnight power is stopped as the temperature of the boil up sensor 6 reaches a specified boil up temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to an electric water heater for boiling hot water at midnight and storing the heated water.

[0002]

2. Description of the Related Art Some electric water heaters use a midnight power system. With this midnight power system, it is possible to use cheap power for a certain period of time at night, for example, 8 hours from 11:00 in the evening to 7:00 in the next morning.

[0003] Electric water heaters use this midnight power,
Boiling tap water or low-temperature hot water (hereinafter referred to as low-temperature water) is boiled and stored in a hot water storage tank. After this, the user uses the boiled hot water in the hot water storage tank. Then, when the electric power time zone is reached at midnight again, the electric water heater boils the low temperature water in the hot water storage tank.

By the way, at the start time of the midnight power time zone,
If all electric water heaters use the power at midnight, the load will be concentrated at the start time. In order to prevent such a situation, there is a peak shift method. According to this method, the amount of heat required to boil hot water in the hot water storage tank is calculated from the temperature of the low-temperature water in the hot water storage tank, the amount of remaining hot water, and the temperature of the remaining hot water. Then, from this required heat quantity, the standby time from the start time of the midnight power time zone until the heater of the electric water heater is energized is calculated. Then, when the calculated standby time ends, the electric water heater supplies midnight power to the heater.

In this way, the load of the electric water heater is prevented from being concentrated at the start time of the midnight power. Such a technique is disclosed in JP-A-58-75655.

[0006]

The peak shift type electric water heater described above has the following problems. Users of electric water heaters may use hot water during the midnight power hours. Even in such a case, the electric water heater calculates the standby time by using the necessary heat amount calculated when entering the midnight power time zone.

Therefore, when hot water is used during the standby time, the amount of heat actually required increases compared to the calculated required heat amount, and the hot water is heated to the hot water storage tank by the end time of the midnight power time zone. I can't raise it.

[0008] An object of the present invention is to provide an electric water heater capable of boiling hot water in a hot water storage tank even if hot water is used during a standby time until the start of energization, excluding such disadvantages. .

[0009]

Means for Solving the Problems In order to achieve the object, an invention according to claim 1 comprises a heating section for boiling hot water with supplied electric power, a hot water storage tank for storing the hot water from the heating section, and a heating section. A water temperature detection unit that detects the temperature of boiling water, and a residual hot water detection unit that detects a temperature according to the amount of residual hot water in the hot water storage tank,
A boiling detection unit that detects the boiling temperature of hot water in the hot water storage tank,
Based on the temperature of the remaining hot water detected by the remaining hot water detection unit and the amount of remaining hot water detected from this temperature, and the temperature of the water detected by the water temperature detection unit, the hot water is heated into the hot water storage tank at the end time of the midnight power time. When the waiting time elapses from the beginning of the midnight power time, the midnight power is supplied to the heating unit and at least one of the water temperature detection unit and the residual hot water detection unit detects a temperature change during the waiting time. And a control device that immediately supplies midnight power to the heating unit and stops supplying midnight power to the heating unit when the temperature detected by the boiling detection unit reaches a predetermined boiling temperature.

According to the first aspect of the present invention, the water temperature detecting section includes:
The heating unit detects the temperature of water boiled, and the residual hot water detecting unit detects a temperature according to the residual hot water amount in the hot water storage tank. The boiling detection unit detects the boiling temperature of the hot water in the hot water storage tank.

The control device stores the hot water at the end time of the midnight power time based on the temperature of the remaining hot water detected by the remaining hot water detecting unit, the amount of remaining hot water detected from the temperature, and the temperature of the water detected by the water temperature detecting unit. The standby time for boiling hot water in the tank is calculated. When the standby time has elapsed from the beginning of the midnight power time, the control device supplies the heating unit with the midnight power.

When at least one of the water temperature detecting section and the remaining hot water detecting section detects a temperature change during the standby time, the midnight power is immediately supplied to the heating section. Thereafter, when the temperature detected by the boiling detecting unit reaches a predetermined boiling temperature, supply of the midnight power to the heating unit is stopped.

According to a second aspect of the present invention, the heating portion for boiling the hot water with the supplied electric power, the hot water storage tank for storing the hot water boiled by the heating portion, the hot water supply pipe for supplying the hot water in the hot water storage tank, and the hot water supply pipe are provided. The hot water supply detection unit that detects the hot water temperature in the hot water supply pipe, the water temperature detection unit that detects the temperature of the water boiled by the heating unit, and the residual hot water detection unit that detects the temperature according to the residual hot water amount in the hot water storage tank,
A boiling detector for detecting the boiling temperature of hot water in the hot water storage tank;
Based on the temperature of the remaining hot water detected by the remaining hot water detection unit and the amount of remaining hot water detected from this temperature, and the temperature of the water detected by the water temperature detection unit, the hot water is heated into the hot water storage tank at the end time of the midnight power time. When the standby time elapses from the beginning of the midnight power time, the midnight power is supplied to the heating unit, and when the hot water supply detection unit detects a temperature change during the standby time, the midnight power is immediately supplied to the heating unit. The electric water heater is provided with a control device that stops the supply of midnight power to the heating unit when the temperature is supplied and the temperature detected by the boiling detection unit reaches a predetermined boiling temperature.

The hot water supply detecting section detects the temperature of the hot water in the hot water supply pipe,
The water temperature detector detects the temperature of the water boiled by the heater. Further, the remaining hot water detection unit detects a temperature corresponding to the amount of remaining hot water in the hot water storage tank, and the boiling detection unit detects a boiling temperature of the hot water in the hot water storage tank.

The control device stores the hot water at the end time of the midnight power time based on the temperature of the remaining hot water detected by the remaining hot water detection unit, the amount of the remaining hot water detected from the temperature, and the temperature of the water detected by the water temperature detection unit. The standby time for boiling hot water in the tank is calculated. When the standby time has elapsed from the beginning of the midnight power time, the control device supplies the heating unit with the midnight power.

At this time, when the hot water supply detecting section detects a temperature change during the standby time, the control device immediately supplies midnight power to the heating section. Then, when the temperature detected by the boiling detection unit reaches a predetermined boiling temperature, the control device stops the supply of the midnight power to the heating unit.

According to a third aspect of the present invention, there is provided a heating section for boiling the hot water with the supplied electric power, a hot water storage tank for storing the hot water boiled by the heating section, a water temperature detecting section for detecting the temperature of the water boiled by the heating section, and a hot water storage. The residual hot water detection unit that detects the temperature according to the residual hot water amount in the tank, the temperature of the residual hot water detected by the residual hot water detection unit and the residual hot water amount detected from this temperature, and the water temperature detected by the water temperature detection unit The standby time for boiling hot water in the hot water storage tank is calculated at the end time of the late-night power time, and the calculation of a new standby time is repeated during the standby time. An electric water heater including a control device that supplies midnight power to the heating unit after a lapse of time.

The water temperature detecting section detects the temperature of the water boiling by the heating section, and the remaining hot water detecting section detects a temperature corresponding to the amount of remaining hot water in the hot water storage tank.

The control device stores the hot water at the end time of the midnight power time based on the temperature of the remaining hot water detected by the remaining hot water detection unit, the amount of the remaining hot water detected from the temperature, and the temperature of the water detected by the water temperature detection unit. The standby time for boiling hot water in the tank is calculated. Further, the control device repeatedly calculates a new standby time during the standby time, and when the latest standby time elapses from the start of the midnight power time, supplies the midnight power to the heating unit.

According to a fourth aspect of the present invention, there is provided a heating section for boiling hot water with supplied electric power, an auxiliary heating section for boiling hot water with supplied electric power, a hot water storage tank for storing the hot water from the heating section, and a heating section. A water temperature detection unit that detects the temperature of boiling water, a remaining hot water detection unit that detects a temperature according to the amount of remaining hot water in the hot water tank, the temperature of the remaining hot water detected by the remaining hot water detection unit, and the amount of remaining hot water detected from this temperature From the water temperature detected by the water temperature detector,
Calculate the required amount of heat for boiling the hot water, calculate the standby time for boiling the hot water in the hot water storage tank at the end time of the midnight power time from this required amount of heat, and calculate the new standby time during the standby time. Repeatedly, when the latest standby time elapses from the beginning of the midnight power time, the control unit supplies midnight power to the heating unit and supplies midnight power to the auxiliary heating unit if the required heat amount is larger than the heat amount by the heating unit. An electric water heater comprising:

The water temperature detecting section detects the temperature of the water boiled by the heating section, and the residual hot water detecting section detects the temperature according to the residual hot water amount in the hot water storage tank.

The control device calculates a required amount of heat for boiling the hot water from the temperature of the remaining hot water detected by the remaining hot water detecting unit, the amount of the remaining hot water detected from the temperature, and the temperature of the water detected by the water temperature detecting unit. The standby time for boiling hot water in the hot water storage tank at the end time of the midnight power time is calculated from the required heat amount.

When the midnight power time starts, the control device repeats the calculation of a new standby time during the standby time. When the latest standby time has elapsed since the beginning of the midnight power time, the control device supplies the midnight power to the heating unit, and supplies the midnight power to the auxiliary heating unit when the required heat amount is larger than the heat amount by the heating unit. .

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described.
This will be described with reference to the drawings.

[Embodiment 1] FIG. 1 shows an electric water heater according to Embodiment 1 of the present invention. This electric water heater comprises a hot water storage tank 1, a heater 2 as a heating unit, a water supply pipe 3, a hot water supply pipe 4, a water temperature sensor 5 as a water temperature detection unit, a boiling sensor 6 as a boiling detection unit, and a residual hot water sensor as a residual hot water detection unit. 7A-7C
And a control device 8.

Hot water storage tank 1 is for storing boiling water. The capacity of the hot water storage tank 1 (hereinafter referred to as tank capacity) is M [liter].

The heater 2 is installed below the hot water storage tank 1. The heater 2 generates heat with electric power supplied from the control device 8 and heats low-temperature water in the hot water storage tank 1. The heater capacity of the heater 2 is P [kW].

The water supply pipe 3 is connected to a lower part of the hot water storage tank 1. The water supply pipe 3 supplies the hot water storage tank 1 with an amount of water equal to the amount of hot water used. The hot water supply pipe 4 is the hot water storage tank 1
Connected to the top. Hot water supply pipe 4 supplies hot water in hot water storage tank 1 to a user.

The water temperature sensor 5 is a sensor for detecting a temperature. The water temperature sensor 5 is installed below the hot water storage tank 1. Water temperature sensor 5 detects the temperature of water supplied from hot water supply pipe 3 to hot water storage tank 1 and sends a temperature signal indicating the water temperature to control device 8.

The boiling sensor 6 is a sensor for detecting a temperature. The boiling sensor 6 is installed in the center of the hot water storage tank 1. The boiling sensor 6 detects the temperature of the hot water boiled by the heater 2 and sends a temperature signal indicating the boiling temperature to the control device 8.

The remaining hot water sensors 7A to 7C are sensors for detecting the temperature. The remaining hot water sensors 7A to 7C are arranged in the hot water storage tank 1 along the longitudinal direction of the hot water storage tank 1. With such an arrangement, the residual hot water sensors 7A to 7C send a temperature signal indicating the height to the control device 8 in accordance with the position of the boundary between the low temperature water and the hot water.

As shown in FIG. 2, the control unit 8 includes a setting unit 8A, a calorie calculating unit 8B, a temperature determining unit 8C, a clock unit 8D,
An energization time calculation unit 8E and an energization control unit 8F are provided.

The setting section 8A is operated by a user of the electric water heater. By this operation, the setting temperature of the boiling water of the heater 2 is set in the setting section 8A.

The calorific value calculation unit 8B calculates a calorific value Q (hereinafter referred to as a necessary calorific value Q) necessary for heating the low temperature water in the hot water storage tank 1 as follows.

That is, the calorie computing unit 8 B
The temperatures Ta, Tb, Tc are obtained from the temperature signals from A to 7C.
Find out. Then, the calorie calculation unit 8B determines the temperature T
a, Tb and Tc are detected, and the remaining hot water amount L is detected.
Find out. At the same time, the calorific value calculation unit 8B causes the temperatures Ta, T
The temperature T _E of the residual hot water is checked by b and Tc.

The calorie computing unit 8 B checks the temperature T _W of the low-temperature water from the temperature signal received from the water temperature sensor 5.

Further, the calorific value calculation unit 8B checks the set temperature, that is, the boiling target temperature T _H from the setting state of the setting unit 8A.

Thereafter, the calorie computing unit 8B calculates the calorific value Q _A of the remaining hot water from the following equation (1).

The remaining hot water in the heat quantity Q _A = the remaining hot water L · (temperature of the remaining hot water T _E - Temperature T _W cold water) ... (1) Furthermore, the amount of heat calculation section 8B, from the following equation (2), The total heat quantity Q _{B of} hot water that can be stored in the hot water storage tank 1 is calculated.

Total heat quantity Q _B = tank capacity M · (boil target temperature T _H −low temperature of water T _W ) (2) Thereafter, the calorie calculation unit 8B calculates the heat quantity according to the equations (1) and (2). Using the calculation result, the required heat quantity Q is calculated from the following equation (3).

Required heat quantity Q = Total heat quantity Q _B −Remaining hot water quantity Q _A (3) In this way, the heat quantity calculation unit 8B calculates the necessary heat quantity Q. Then, the heat quantity calculation unit 8B calculates the required heat quantity Q.
Is sent to the energization time calculation unit 8E.

Temperature determination section 8C determines whether or not water has flowed into hot water storage tank 1 based on temperature signals from water temperature sensor 5 and residual hot water sensors 7A to 7C. For this purpose, the temperature determination unit 8C performs the following determination processing.

This determination process is performed using the water temperature sensor 5. That is, the temperature determination unit 8C checks the water temperature in the hot water storage tank 1 from the temperature signal of the water temperature sensor 5. After that, the temperature determination unit 8C checks the temperature change ΔT of the water temperature sensor 5 with respect to the time Δt1. Then, the temperature determination unit 8C
Checks whether the temperature change ΔT1 and the time Δt satisfy the following expression (4).

(ΔT1 / Δt) <A (4) In Equation (4), the constant A is a preset negative value.

Normally, when the hot water in the hot water storage tank 1 is boiled and then this hot water is used, water is supplied from the water supply pipe 3 to the hot water storage tank 1 as shown in FIG. As a result, in the hot water storage tank 1, a layer of low temperature water 201 and high temperature hot water 2
02 layer is formed. After that, the temperature of the low-temperature water 201 rises due to the slight movement of heat from the hot water 202. In such a state, when the hot water 202 is used, the temperature of the low-temperature water 201 decreases due to the water from the water supply pipe 3.
As a result, the temperature change ΔT1 greatly changes in the negative direction. Therefore, if the temperature change ΔT1 and the time Δt satisfy the expression (1), the temperature determination unit 8C determines that “there is a temperature change due to ingress of water” due to the use of hot water.

The temperature determining section 8C includes a remaining hot water sensor 7A.
The determination process using 7C is performed. That is, the temperature determination unit 8
C checks the temperature of hot water in hot water storage tank 1 from each temperature signal of remaining hot water sensors 7A to 7C. After this, the temperature determination unit 8C
Examines the temperature change ΔT2 of the remaining hot water sensors 7A to 7C with respect to the time Δt. Then, the temperature determination unit 8C
It is checked whether the temperature change ΔT2 and the time Δt satisfy the following equation (5).

A ≦ (ΔT2 / Δt) <0 (5) In the hot water storage tank 1, the boundary between the low temperature water 201 and the high temperature hot water 202 is at the position 211 (the portion shown by the solid line in FIG. 3). For example, the remaining hot water sensor 7A detects the temperature of the hot water 202. As a result, when the temperature checked by the temperature signal of the remaining hot water sensor 7A maintains a constant state, the temperature determination unit 8C
Determines that there is no temperature change.

The temperature determination section 8C determines the temperature change ΔT2
When the time Δt satisfies the expression (5), it is determined that “there is a temperature change due to heat radiation”. That is, a slight amount of heat is transferred from the hot water 202 to the cold water 201, and the temperature change ΔT2 of the hot water 202 changes in the negative direction.
Therefore, the temperature change ΔT2 and the time Δt satisfy the expression (5).

The temperature determination section 8C determines the temperature change ΔT2
It is checked whether or not and the time Δt satisfy the following expression (6).

(ΔT2 / Δt) <A (6) When the boundary between the low-temperature water 201 and the high-temperature hot water 202 moves to the position 212 (the portion indicated by the chain line in FIG. 3) due to the use of the hot water, the residual hot water The sensor 7A changes from high temperature to low temperature. As a result, the change ΔT2 in temperature, which is checked from the temperature signal of the remaining hot water sensor 7A, largely changes in the minus direction. Therefore, if the temperature change ΔT2 and the time Δt satisfy the expression (6), the temperature determination unit 8C determines that “there is a temperature change due to ingress of water”.

In this way, the temperature determination unit 8C uses the temperature signals from the water temperature sensor 5 and the residual hot water sensors 7A to 7C to "no temperature change""temperature change due to heat radiation""temperature change due to water intrusion". "Yes" is determined. When the temperature determination unit 8C determines that “there is a temperature change due to water intrusion”, it sends a determination signal indicating this determination to the energization time calculation unit 8E.

The clock section 8D is a circuit for counting the time of day. The clock unit 8D sends a time signal indicating the current time to the energization time calculation unit 8E.

The energization time calculator 8E calculates the energization time h of the heater 2 using the midnight power system. The energization time calculation unit 8E calculates an energization time h for boiling hot water within eight hours at night in the midnight power system.

When the energization time calculation unit 8E receives the required heat quantity Q from the heat quantity calculation unit 8B, the energization time h is calculated using the following equation (7) according to the relationship of 1 [kW] = 860 [kcal]. To do.

Energization time h = required heat quantity Q / (860 / heater capacity P / efficiency δ) (7) Thereafter, the energization time calculation unit 8E uses the following equation (8) to calculate the energization start time h _S To calculate.

Energization start time h _S = 8 hours-energization time h (8) The energization time calculation unit 8E determines whether the current time is the start time of the midnight power time zone based on the time signal from the clock unit 8D. Find out. When the time signal indicates the start time, the energization time calculation unit 8E sends an energization signal indicating energization to the energization control unit 8F after the energization start time h _S has elapsed from the start time. Thereafter, the energization time calculation unit 8E stops outputting the energization signal to the energization control unit 8F simultaneously with the end of the midnight power time zone, that is, immediately after the elapse of the energization time h. Thus, the energization time calculation unit 8E performs control by the peak shift method.

Further, upon receiving a determination signal indicating "there is a temperature change due to water intrusion" from the temperature determining unit 8C, the power-on time calculating unit 8E sets the power-on time h _S = 0.

That is, when the current time is during the energization start time h _S which is the standby time until the energization start, when water flows into the hot water storage tank 1 due to the use of hot water, the energization signal indicating the energization is energized. Immediately send it to the control unit 8F.

The energization controller 8F supplies the midnight power to the heater 2 while receiving the energization signal from the energization time calculator 8E.
To supply. The power supply control unit 8F receives the temperature signal from the boiling sensor 6 and, based on this signal,
Detects the temperature of the heated water inside. Then, the energization control unit 8F is irrelevant while receiving the energization signal,
When the detected temperature reaches the boiling temperature, the supply of electric power to the heater 2 is stopped.

Next, the operation of the first embodiment will be described.

The user of the electric water heater operates the setting section 8A to set the boiling temperature of hot water and the like. Control device 8 starts control for boiling hot water in hot water storage tank 1 according to the setting for setting portion 8A.

In other words, the calorific value calculation unit 8B has the water temperature sensor 5
The required heat quantity Q is calculated based on the temperature signals from the remaining hot water sensors 7A to 7C. The calorie computing unit 8B sends the calculated required calorie Q to the power-on time computing unit 8E. Energization time calculation unit 8E
Calculates the energization time h when the required heat quantity Q is received.
Further, the heat amount calculation unit 8B calculates the energization start time h _S from the energization time h.

On the other hand, the energization time calculation unit 8E is provided with a clock unit 8D.
From the time signal to check if the current time has reached the start time of the midnight power time zone. When the energization start time h _S elapses after the time signal indicates the start time, the energization time calculator 8E sends an energization signal indicating energization to the energization controller 8F.
Send to Upon receiving the energization signal, energization control unit 8F starts supplying midnight power to heater 2. As a result, the heater 2 starts heating low-temperature water.

After that, the energization time calculation unit 8E stops outputting the energization signal to the energization control unit 8F at the same time as the end of the midnight power time period. As a result, the energization control unit 8F stops supplying midnight power to the heater 2. Also, the end of midnight power time zone, the temperature signal from the heating-up sensor 6 indicates a heating-up target temperature T _H, the energization control section 8F determines that the hot water is raised aside, midnight electric power to the heater 2 Stop the supply of.

The energization of the heater 2 is controlled in this way. As a result, the energization time of the heater 2 is moved to the later of the late night power time zone, and the energization end time is adjusted so that the end of the midnight power time zone.

By the way, the temperature judging section 8C receives the temperature signals from the water temperature sensor 5 and the remaining hot water sensors 7A to 7C based on the temperature signals.
It is determined whether or not “there is a temperature change due to water intrusion”.
When the temperature determination unit 8C determines that “there is a temperature change due to water intrusion”, it sends a determination signal indicating the determination result to the energization time calculation unit 8E. Upon receiving the determination signal from the energization time calculation unit 8E, the energization time calculation unit 8E sets the energization start time h _S = 0. Then, the energization time calculation unit 8E immediately sends an energization signal indicating energization to the energization control unit 8F. Energization control unit 8
When F receives the energization signal, it starts supplying midnight power to the heater 2. Thus, the heater 2 starts heating the low-temperature water.

[0067] Thereafter, when the temperature signal from the heating-up sensor 6 indicates a heating-up target temperature T _H, the energization control section 8F determines that the hot water is A surge stops supplying the midnight power to the heater 2.

As described above, according to the first embodiment, when hot water is used during the standby time in the midnight power time zone, the heater 2
Power to the night immediately. As a result, the shortage of hot water caused by the use of hot water during the standby time can be eliminated, and the hot water can be boiled in the hot water storage tank 1. Further, since the use of the hot water is detected by using both the water temperature sensor 5 and the remaining hot water sensors 7A to 7C, the hot water can be surely boiled in the hot water storage tank 1.

[Second Embodiment of the Invention] FIG. 4 shows an electric water heater according to a second embodiment. In the second embodiment, the hot water supply sensor 9 and the control device 1 are different from the first embodiment described above.
Only 0 is different and the others are similar. In the following description, only the different points will be described, and the overlapping portions will be denoted by the same reference numerals in the drawings and will not be described.

Hot water supply sensor 9 of the second embodiment is a sensor for detecting the temperature. The hot water supply sensor 9 is connected to the hot water supply pipe 4.
It is installed in. Hot water supply sensor 9 detects the temperature of the hot water in hot water supply pipe 4 and sends a temperature signal indicating the hot water temperature to control device 10.

As shown in FIG. 5, the control device 10 includes a setting unit 10A, a calorie calculating unit 10B, a detecting unit 10C, and a clock unit 1.
0D, energization time calculation unit 10E and energization control unit 10F. Setting unit 10A, calorie calculation unit 10B, clock unit 10
D and the energization control unit 10F are the setting unit 8 of the first embodiment.
A, calorie calculator 8B, clock 8D, and power supply controller 8F
Since each is the same as the above, the description is omitted.

The detector 10C detects whether or not hot water is used from the temperature signal of the hot water supply sensor 9. Therefore, the detection unit 10C performs the following processing.

The detecting section 10 C checks the temperature of the hot water in the hot water supply pipe 4 from the temperature signal of the hot water supply sensor 9. Thereafter, detection unit 10C causes temperature change Δ of hot water supply sensor 9 with respect to time Δt.
It is checked whether T3 satisfies the following expression (9).

(ΔT3 / Δt) ≦ 0 (9) When the time Δt and the temperature change ΔT3 satisfy the expression (9),
The detecting unit 10C determines that “no hot water is used”. That is, when the hot water is filled in the hot water supply pipe 4 in a stationary state,
The heat of the hot water is gradually taken away by the hot water supply pipe 4 and the outside air around the hot water supply pipe 4. As a result, when the hot water is stationary inside the hot water supply pipe 4, that is, when the hot water is not used, the temperature change ΔT3
Changes slightly in the minus direction, so that the temperature change ΔT3
And time Δt satisfy expression (9).

Further, detecting section 10C checks whether or not temperature change ΔT3 of hot water supply sensor 9 with respect to time Δt satisfies the following equation (10).

(ΔT3 / Δt)> 0 (10) When the temperature change ΔT3 and the time Δt satisfy the expression (10), the detecting unit 10C determines that “hot water is used”. That is, when the hot water starts to flow in the hot water supply pipe 4, the temperature in the hot water supply pipe 4 rises due to the hot water from the hot water storage tank 1, and the temperature change ΔT3 greatly changes in the positive direction. Expression (10) is satisfied.

In this way, the detection unit 10C determines "no hot water used" or "hot water used" based on the temperature signal from the hot water supply sensor 9. Then, when determining that the hot water is used, the detection unit 10C sends a determination signal indicating this determination to the energization time calculation unit 10E.

The energization time calculation unit 10E is the heat quantity calculation unit 10E.
When the required amount of heat Q is received from B, the energization start time h _S is calculated using the equations (7) and (8) as in the first embodiment. After that, the energization time calculation unit 10E causes the clock unit 1 to
According to the time signal from 0D, an energization signal indicating energization is sent to the energization control unit 10F after the energization start time h _S has elapsed from the start time of the midnight power time zone. Then, the energization time calculation unit 10E stops outputting the energization signal to the energization control unit 10F at the same time as the end of the midnight power time period.

Further, the energization time calculation unit 10E includes the detection unit 1
When a determination signal indicating “the use of hot water” is received from 0C, the power supply start time h _S = 0.

That is, when the current time is during the energization start time h _S which is the standby time until the energization start, when water flows into the hot water storage tank 1 due to the use of hot water, the energization signal indicating the energization is energized. Send it immediately to the control unit 10F.

As described above, according to the second embodiment, when hot water is used during the standby time in the midnight power time zone, the midnight power is immediately supplied to heater 2. Thereby, the shortage of hot water generated due to the use of hot water during the standby time can be eliminated, and the hot water can be heated to the hot water storage tank 1.

Third Embodiment FIG. 6 shows an electric water heater according to a third embodiment. The third embodiment is different from the first embodiment described above only in the control device 11, and is otherwise the same. In the following description, only the different points will be described, and the overlapping portions will be denoted by the same reference numerals in the drawings and will not be described.

As shown in FIG. 7, the control device 11 according to the third embodiment includes a setting unit 11A, a calorific value calculation unit 11B, a clock unit 1
1C, energization time calculation unit 11D, storage unit 11E and energization control unit 11F. The setting unit 11A, the clock unit 11C, and the energization control unit 11F are the setting unit 8A of the first embodiment,
Since they are the same as the clock section 8D and the energization control section 8F, the description is omitted.

Upon receiving the temperature signals from the water temperature sensor 5 and the residual hot water sensors 7A to 7C, the calorific value calculation unit 11B receives the residual hot water amount L, the residual hot water temperature T _E , and the low temperature water as in the first embodiment. The temperature T _{W and the} like are checked. Further, the calorie calculation unit 11B
Calculates the required heat quantity Q from these values. The calorific value calculation unit 11B performs such calculation of the required calorific value Q every predetermined time. Then, every time the required heat quantity Q is calculated, the calculated value is sent to the energization time calculation unit 11D.

The storage section 11E is a RAM (Random Access) for temporarily storing the data from the energization time calculation section 11D.
Memory).

The energization time calculation unit 11D is provided with a heat amount calculation unit 11
Upon receipt of the necessary quantity of heat Q from B, similarly to Embodiment 1, (7), (8) using the equation, it calculates the energization time h energizing start time h _S. After this, the energization time calculation unit 11
D stores the calculated energization time h and energization start time h _S in the storage unit 11E. Energization time calculation unit 11D, each time receiving the necessary heat quantity Q from the heat calculation unit 11B, performs repeat these processes, thereby always store the latest energization time h energization start time h _S in the storage unit 11E.

The energization time calculation unit 11D has a heat quantity calculation unit 11D.
The process of calculating the energization time h and the energization start time h _S with the required heat quantity Q from B is performed from the start time of the midnight power time zone until the latest energization start time h _S stored in the storage unit 11E elapses. .

When the latest energization start time h _S has elapsed from the midnight power start time, the energization time calculation unit 11D sends it to the energization signal storage unit 11E indicating the start of energization. Thereafter, the energization time calculation unit 11D, at the same time as the end of the midnight power time zone,
That is, immediately after the elapse of the energization time h, the output of the energization signal to the energization control unit 11F is stopped.

As described above, according to the third embodiment, even when hot water is used during the standby time in the midnight power time zone, the required heat quantity Q, the energizing time h using this value, and the energizing start time at each predetermined time. h _S is calculated. Thus, until just prior to being energized to the heater 2, so to calculate the required amount of heat Q accurately, midnight when power time zone ends can be increased boiling hot water heating-up target temperature T _H to the hot water storage tank 1.

[Fourth Embodiment of the Invention] FIG. 8 shows an electric water heater according to a fourth embodiment. In the fourth embodiment, only the auxiliary heater 2A and the control device 12 are different from the first embodiment described above, and the other points are the same. In the following description, only the different points will be described, and the overlapping portions will be denoted by the same reference numerals in the drawings and will not be described.

[0091] The auxiliary heater 2A is installed near the heater 2 and below the hot water storage tank 1. Like the heater 2, the auxiliary heater 2A generates heat with electric power supplied from the control device 12, and heats low-temperature water in the hot water storage tank 1.

As shown in FIG. 9, the control unit 12 includes a setting unit 12A, a clock unit 12B, a storage unit 12C, and a control unit 1.
It has 2D. The setting unit 12A and the clock unit 12B are the same as the setting unit 8A and the clock unit 8D of the first embodiment, respectively, and thus the description is omitted. In addition, the storage unit 12C
Is the same as the storage unit 11E of the third embodiment, and a description thereof will not be repeated.

The control unit 12D includes the heater 2 and the auxiliary heater 2
The control of A is performed according to the procedure shown in FIGS. That is, the control unit 12D checks the current time from the time signal of the clock unit 12B (step S1) and determines whether the current time is the measurement time (step S2).

If the current time is not the measured time, the control unit 1
2D returns the process to step S1. The cycle generated by the measurement time is performed every predetermined time. In step S2, if the current time is the measurement time, the control unit 12D
Examines the temperature of the cold water from the water temperature sensor 5, examine the temperature T _E of the remaining hot water L and the remaining hot water from the temperature signals of the remaining hot water sensor 7A-7C, also from the setting state of the setting unit 8A, the set temperature i.e. The boiling target temperature T _H is checked (step S3).

The control section 12D calculates the required heat quantity Q using the value checked in step S3 and the equations (1) to (3) (step S4). After calculating the required heat quantity Q, the control unit 12D calculates the energization time h and the energization start time h _S using the equations (7) and (8) (step S5). After calculating the energization time h and the energization start time h _S , the control unit 12D stores these times in the storage unit 12C (Step S6). When the storage of the time ends, the control unit 12D
When the current time is from the start time of the midnight power time zone, the storage unit 1
It is determined whether or not the energization start time h _S stored in 2C has elapsed (step S7).

Whether the current time is the start time of the midnight power time zone
Energization start time h_SIf the time has not elapsed, the control unit 1
2D returns the process to step S1. At the start of energization
Between h _SHas passed, the control unit 12D sets the heater 2
Is supplied with power at midnight (step S8).

When the midnight power supply is started, the control unit 12
D is the temperature signal of heating-up sensor 6, check the temperature of the hot water (step S9), and the temperature determine whether the heating-up target temperature T _H (step S10). If the temperature is the boiling target temperature T _H , the control unit 12D stops supplying the midnight power to the heater 2 (Step S11).

[0098] Further, in step S10, if the temperature indicated by the heating-up sensor 6 is reached the heating-up target temperature T _H, the control unit 12D checks the temperature of the cold water from the water temperature sensor 5,
The amount L of remaining hot water and the temperature T _E of the remaining hot water are checked from the temperature signals of the remaining hot water sensors 7A to 7C, and the boiling target temperature T _H is checked from the setting state of the setting unit 8A (step S12).

The control section 12D calculates the required heat quantity Q after heating by the heater 2 using the value checked in step S12 and the equations (1) to (3) (step S13). After calculating the required heat quantity Q, the control unit 12D calculates the energization time h using Expression (7) (Step S14).

After calculating the energizing time h, the control section 12D determines whether or not the heating is completed based on the energizing time h (step S15). In order to make this determination, the control unit 12D performs the following. That is, the control unit 12D determines the time T during which the heater 2 has already been energized.
The sum of _U and the energization time h calculated in step S13 is calculated. After that, the control unit 12D checks whether the calculated sum satisfies the following expression (11).

Energization time h + time T _U ≦ 8 (11) If the calculated sum satisfies the equation (11),
It is determined that boiling within the midnight power time zone of 8 hours is completed. If the calculated sum does not satisfy the expression (11), the control unit 12D determines that the boiling is not completed.

When the controller 12D determines in step S15 that boiling has not been completed, it supplies midnight power to the auxiliary heater 2A (step S16). This promotes heating of the low-temperature water. When power is supplied to auxiliary heater 2A, control unit 12D returns the process to step S9. When determining that the boiling is completed in step S15, control unit 12D returns the process to step S9 and repeats the process.

As described above, according to the fourth embodiment, even when hot water is used during the standby time of the midnight power time zone, the required heat quantity Q and the energization time h and the energization start time using this value are calculated at each predetermined time. h _s is calculated. At this time, since a large amount of hot water is used, the calculated required heat quantity Q becomes large and the heater 2
Be expected shortage of heat by, makes up for the lack of heat in the auxiliary heater 2A, the end of the midnight power time zone can be increased boiling hot water heating-up target temperature T _H to the hot water storage tank 1.

The first to fourth embodiments have been described above. In the first to fourth embodiments, the present invention is applied to the electric water heater of the internal heating type, which is provided with the heater 2 and the auxiliary heater 2A inside the hot water storage tank 1. In addition to this internal heating method,
There is an electric water heater of an external heating type which is provided with a heating device outside the hot water storage tank 1 and stores hot water boiled by the heating device in the hot water storage tank 1 to boil the hot water. The present invention is also applicable to this external heating type electric water heater.

[0105]

As described above, according to the first aspect of the present invention, when water is replenished in the hot water storage tank by using hot water, the replenishment of the water is performed by the water temperature detecting unit or the remaining hot water detecting unit. , And the midnight power is immediately supplied to the heating unit, so that the hot water can be heated in the hot water storage tank at the end time of the midnight power time.

According to the second aspect of the present invention, the use of hot water is detected by a change in temperature of the hot water supply detection section, and the midnight power is immediately supplied to the heating section. At the end of time, hot water can be boiled in the hot water storage tank.

According to the third aspect of the invention, the change of the standby time due to the use of hot water is corrected, and the supply of the late-night power to the heating unit is controlled by the latest standby time. Can boil hot water into a hot water storage tank.

According to the fourth aspect of the present invention, the change of the standby time due to the use of hot water is corrected to control the supply of late-night electric power to the heating unit by the latest standby time, and at this time, the amount of heat generated by the heating unit If the required amount of heat is larger than the above, the auxiliary heating unit is used, so at the end time of the midnight power time,
Hot water can be boiled in the hot water storage tank.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram showing an electric water heater according to a first embodiment.

FIG. 2 is a block diagram showing an example of a control device according to the first embodiment.

FIG. 3 is a diagram showing a state inside a hot water storage tank.

FIG. 4 is a basic configuration diagram showing an electric water heater according to a second embodiment.

FIG. 5 is a block diagram illustrating an example of a control device according to a second embodiment.

FIG. 6 is a basic configuration diagram showing an electric water heater according to a third embodiment.

FIG. 7 is a block diagram showing an example of a control device according to a third embodiment.

FIG. 8 is a basic configuration diagram showing an electric water heater according to a fourth embodiment.

FIG. 9 is a block diagram showing an example of a control device according to a fourth embodiment.

FIG. 10 is a flowchart showing a control procedure of a control unit according to the fourth embodiment.

FIG. 11 is a flowchart showing a control procedure of a control unit according to the fourth embodiment.

FIG. 12 is a flowchart illustrating a control procedure of a control unit according to the fourth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hot water storage tank 2 Heater 3 Water supply pipe 4 Hot water supply pipe 5 Water temperature sensor 6 Boiling sensor 7A-7C Remaining hot water sensor 8 Control device

Claims (4)

[Claims] 1. A heating unit for boiling hot water with the supplied electric power, a hot water storage tank for storing the hot water boiled by the heating unit, a water temperature detection unit for detecting the temperature of water boiled by the heating unit, and an amount of remaining hot water in the hot water storage tank. A hot water detector that detects the temperature according to the temperature, a boiling detector that detects the boiling temperature of the hot water in the hot water storage tank, the temperature of the remaining hot water detected by the remaining hot water detector, and the amount of remaining hot water detected from this temperature And, based on the water temperature detected by the water temperature detection unit, calculates the standby time for boiling hot water in the hot water storage tank at the end time of the late-night power time, and when the standby time elapses from the beginning of the late-night power time When the midnight power is supplied to the heating unit and at least one of the water temperature detection unit and the remaining hot water detection unit detects a temperature change during the standby time, the midnight power is immediately supplied to the heating unit and the temperature detected by the boiling detection unit is detected. When the heating temperature reaches the specified boiling temperature, Electric water heater and a control device for stopping the supply of the midnight power against. 2. A heating unit for boiling hot water with supplied electric power, a hot water storage tank for storing hot water boiled by the heating unit, a hot water supply pipe for supplying hot water in the hot water storage tank, and a hot water supply pipe provided in the hot water supply pipe. A hot water supply detector that detects the temperature of the hot water, a water temperature detector that detects the temperature of the water being boiled by the heater, a remaining hot water detector that detects a temperature corresponding to the amount of the remaining hot water in the hot water storage tank, Based on the boiling temperature detector that detects the boiling temperature, the temperature of the residual hot water detected by the residual hot water detector, the amount of residual hot water detected from this temperature, and the water temperature detected by the water temperature detector, the midnight power hours When the standby time for boiling the hot water in the hot water storage tank is calculated at the end time of, and when the standby time elapses from the beginning of the midnight power time, the hot power is supplied to the heating unit and the hot water detector detects the temperature during the standby time. When a change is detected, midnight power is immediately supplied to the heating section. And, if the temperature of the heating-up detection unit detects reaches a predetermined heating-up temperature, electric water heater and a control device for stopping the supply of the midnight power to the heating unit. 3. A heating unit for boiling hot water with the supplied electric power, a hot water storage tank for storing the hot water from the heating unit, a water temperature detecting unit for detecting a temperature of the hot water for the heating unit, and an amount of remaining hot water in the hot water storage tank. Based on the temperature of the residual hot water detected by the residual hot water detection unit, the amount of residual hot water detected from this temperature, and the temperature of the water detected by the water temperature detection unit. At the end time of the time, the standby time for boiling hot water in the hot water storage tank is calculated, and a new standby time is repeatedly calculated during the standby time. An electric water heater having a control device for supplying electric power to the nighttime. 4. A heating unit for boiling the hot water with the supplied electric power, an auxiliary heating unit for boiling the hot water with the supplied electric power, a hot water storage tank for storing the hot water boiled by the heating unit, and a temperature of the water boiled by the heating unit. A water temperature detecting section for detecting, a remaining hot water detecting section for detecting a temperature corresponding to an amount of remaining hot water in the hot water storage tank, a temperature of the remaining hot water detected by the remaining hot water detecting section, a remaining hot water amount detected from the temperature, and a water temperature detecting section. Calculate the required heat for boiling the hot water from the temperature of the water detected by, and calculate the standby time for boiling the hot water in the hot water storage tank at the end of the midnight power time from the required heat. When the latest standby time elapses from the start of the midnight power time, midnight power is supplied to the heating unit, and if the required heat amount is larger than the heat amount by the heating unit, auxiliary heating is performed. Power to the department at midnight Electric water heater and a control device.