JPS647301B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a control device for a hot water storage type electric water heater that uses late-night electricity, and calculates the required amount of heat to be stored in a hot water storage tank based on the actual amount of heat used by the user. In this way, the capacity of conventionally fixed hot water storage type electric water heaters can be used according to the user's needs, and multiple hot water storage type electric water heaters can be controlled equally by a central control unit. It is intended to.

FIG. 1 is a block diagram of a general hot water storage type electric water heater, and FIG. 2 is a main electrical circuit diagram of a conventional hot water storage type electric water heater.

In these figures, 1 is a hot water storage tank, 2 is a water supply pipe, 3 is a hot water supply pipe, 4 is a hot water tap, 5 is a heating element, 6
is an automatic temperature controller, 7 is a power supply, and 8 is a time switch for late-night power, which is generally turned on around 23:00.
8 hours from 7:00 to 7:00 the next morning.

Next, the operation of the conventional example having the above configuration will be explained. When the midnight power supply start time arrives, the contact of the time switch 8 is closed and the supply of electricity to the heating element 5 is started. And the water temperature in hot water storage tank 1 is 85℃.
When this happens, the contacts of the automatic temperature regulator 6 are opened and the power supply to the heating element 5 is stopped. Thereafter, the water temperature is maintained at 85°C by opening and closing the automatic temperature controller 6, and in this way, the entire stored hot water is heated to 85°C every morning.

In this way, in order to increase the efficiency of hot water storage, electric hot water heaters are designed to set the boiling temperature as high as possible, and stop heating when the set temperature is reached. However, users do not use high-temperature hot water as it is, but mix it with water and use it as a mixed hot water at around 40 to 45 degrees Celsius. The formula for determining the amount of mixed hot water obtained is as follows.

Now, the hot water storage tank capacity is Vt (), hot water storage tank 1
If the boiling temperature in the water is To (℃), the temperature of the mixed water to be obtained is Tm (℃), and the temperature of the water to be mixed (water supply temperature) is Ti (℃), the mixed hot water volume Vm ()
can be expressed as Vm=Vt×To−Ti/Tm−Ti().

In this formula, the water supply temperature Ti varies greatly depending on the season. In Tokyo, temperatures range from around 5°C in winter to around 27°C in summer. Therefore, the amount of hot water that can be obtained as mixed hot water at an appropriate temperature is small in the winter and large in the summer. That is, when the boiling temperature To is 85°C, the amount of mixed hot water Vm obtained when the water supply temperature Ti is 5°C is 1.6 times that obtained when the water supply temperature Ti is 27°C.

On the other hand, the amount of hot water used is almost constant throughout the year, or rather, the actual amount used is generally lower in the summer because hot water is used at a lower temperature, and the amount of hot water remaining in the summer is larger than in the winter. Furthermore, some users use only 1/2 or 2/3 of the rated amount due to a decrease in the number of family members, leaving a large amount of hot water available each day.

In this way, if the water supply temperature is high and there is residual hot water, the hot water will boil quickly and the hot water will be left unused for a long time.

In this way, leaving unnecessarily high-temperature hot water unused for a long time has the disadvantage of increasing heat loss due to natural heat radiation from the hot water storage tank 1 and heat radiation from hot water stagnant in the pipes. It was hot. In addition, when multiple units were operated in parallel, there was a problem in that the load was concentrated in the first half of the late-night power supply time.

This invention attempts to eliminate these drawbacks, and stores the actual amount of hot water used in a storage device as data, for example, the amount of heat used in relation to the amount of hot water used over the past few days, and this data is updated every day with the actual amount of hot water used for that day. It is updated by replacing the oldest data, that is, it has a learning function, and based on this data, the required amount of heat is calculated and the boiling temperature is set so that the required amount of mixed hot water is always obtained. By controlling the supply of power to the heating element in accordance with the set value of the boiling temperature, the amount of remaining hot water is reduced and heat loss after boiling is eliminated as much as possible. This invention manages multiple hot water storage type electric water heaters with a central control device, and distributes the start time of energization according to the boiling temperature so that the load is evenly distributed throughout the late night power supply period. This is what I decided to do.

Fig. 3 shows the configuration of a hot water storage type electric water heater which is the object of control of the present invention, with reference numerals 1 to 5, 7, and 8.
shows the same thing as FIGS. 1 and 2. 9 is a temperature detection means (hereinafter referred to as a temperature sensor) such as a thermistor, which continuously detects the temperature of water supplied from the water supply pipe 2 into the hot water storage tank 1, and also detects the temperature of boiling water. Yes, it is located at the bottom of the hot water storage tank 1. Note that this temperature sensor 9
may be provided separately to detect the temperature of water and the temperature of hot water, respectively. Reference numeral 10 denotes a switch for controlling the supply of electricity to the heating element 5, which is opened and closed by operation of a control section to be described later. Reference numeral 11 denotes the above-mentioned control unit, which includes a storage device 12, a required heat amount setting device 13, a boiling temperature setting device 14, an energization control device 15, and a usage amount calculation device 16. A water meter 17 is attached to the water supply pipe 2 and indirectly measures the flow rate of hot water flowing out from the hot water storage tank 1. For this purpose, for example, an encoder is attached to a metering propeller that rotates according to the flow rate, and generates the number of pulses according to the flow rate. Note that the water meter 17 may be provided on the hot water supply pipe 3 side.

The storage device 12 stores the amount of heat used for the amount of hot water calculated by the amount of heat used calculation device 16, and the performance K _G for the past several days as data. This data is set to a fixed number of days, such as 10 days, so that the latest data for the previous day is always stored and the oldest data is deleted in sequence.

The required heat amount setting device 13 is, for example, a storage device 12.
Call the maximum value K _G max of the data stored within it (out of 10 days in the example above) from
Calculate the required amount of heat Ks (kcal) to be stored in the hot water storage tank 1 by multiplying by a constant C based on the margin rate (for example, 1.1 if the margin rate is 10%) as Ks = K _G max × C do.

The boiling temperature setting device 14 sets the required amount of heat Ks
(kcal), hot water storage tank capacity Vt (), water supply temperature Ti
(°C), calculate the boiling temperature To (°C) using the formula below.

To=Ks/Vt+Ti The energization control device 15 controls the on/off of the switch 10. It is turned on by a command from the central control device, which will be described later, and the temperature sensor 9 rises to the temperature.
Turns off when To is detected.

The amount of heat used calculation device 16 calculates the amount of heat used on the previous day, assuming that the amount of hot water used by the water meter 17 is v (), the temperature of the supplied water is Ti (℃), and the boiling temperature of the previous day is To (℃).
K _G is calculated as K _G =v×(To−Ti).

FIG. 4 is a block diagram of the overall configuration showing one embodiment of the present invention. In this figure, 100A, 100
B, . . . 100N indicates the above-mentioned hot water storage type electric water heater according to the present invention, and inside the control unit 11, only the boiling temperature setting device 14 and the energization control device 15 necessary for explanation are shown, and the others are omitted. There is. 20
is a central control unit, each hot water storage type electric water heater 100A
Data on the boiling temperature To is received from the boiling temperature setting device 14 of ~100N, and the respective energization start times are distributed so that the load is evenly distributed throughout the late night power supply time zone. There are various methods of leveling, but simply boiling temperature To
Each hot water storage type electric water heater is turned on in order from the one with the highest
Just turn it off. In short, the central controller 20
0 issues a control command to each energization control device 15.

Next, the operation of the above embodiment will be explained with reference to FIG. Note that (1) to (13) in FIG. 5 represent each step.

It starts (1), and at midnight, for example, 23:00, the time switch 8 is turned on (2). When control starts at the same time as this power supply, first, the daily hot water usage record,
That is, before midnight power is supplied to the electric water heater, the amount of heat K _G used for the amount of hot water used that day is determined by the amount of heat used calculation device 16 (3), and this data is stored in the storage device 12 as the latest data. The data is updated by replacing the input data with the oldest data among the data previously stored in the storage device 12 (4). Next, the largest K _G max of the latest data is called from the storage device 12 (5),
In the required heat amount setting device 13, the required heat amount Ks is set by multiplying K _G max by a constant C based on the margin rate.
(6). Moreover, in the boiling temperature setting device 14,
The temperature of the water supply in the hot water storage tank 1 is determined by the temperature sensor 9.
Measure Ti (7) and set the boiling temperature To from the hot water storage tank capacity Vt (8).

In this way, when the boiling temperature To set for each water heater is input to the central control device 200, the central control device 200
Based on this, a signal to start energization is sent to the energization control device of each water heater so that the load is evenly distributed throughout the late-night power supply period. In this way, when each signal to start energization is received, energization to the heating element 5 is started.
(9). Then, when the water temperature reaches the boiling temperature To (10), the power to the heating element 5 is turned off (11).

Then, the midnight power supply time end time, for example, 7
When the time comes, time switch 8 turns off (12),
The sequence is stopped (13).

In addition, in the above embodiment, the required heat amount setting device 13
Although the maximum K _G max among the data in the storage device 12 was used to calculate the required heat amount Ks, the average over a fixed number of days or other data may also be used. Furthermore, a microcomputer equipped with a central processing unit (CPU) can be used as the control unit 11.

Further, in the above embodiment, each hot water storage type electric water heater was controlled to be energized in order from the one with the highest boiling temperature, but the present invention is not limited to this.
A plurality of units may be energized at the same time, and the point is that the power consumption may be leveled as much as possible in the end.

As explained in detail above, the present invention stores the latest data on the amount of heat used in relation to the amount of hot water used in the storage device as the results for the past several days, and based on this data, the required amount of heat is stored in the hot water storage tank. Since the boiling temperature can be set, the amount of hot water can be obtained every day according to the user's actual situation, which reduces the amount of remaining hot water, which reduces heat loss after boiling and reduces maintenance costs. Become. Furthermore, the central control unit allocates the start time of energizing multiple hot water storage type electric water heaters according to the boiling temperature so that the load is evenly distributed throughout the late-night power supply period. It has the advantage of increasing efficiency.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of a typical hot water storage type electric water heater.
Fig. 2 is a main electrical circuit diagram of a conventional hot water storage type electric water heater, Fig. 3 is a block diagram showing an embodiment of the present invention, and Fig. 4 is a block diagram showing the overall structure of an embodiment of the invention. FIG. 5 is also a control flowchart. In the figure, 1 is a hot water storage tank, 2 is a water supply pipe, 3 is a hot water supply pipe, 4 is a hot water tap, 5 is a heating element, 7 is a power supply, 8 is a time switch, 9 is a temperature sensor, 10 is a switch, and 11 is a control unit , 12 is a storage device, 13 is a required heat amount setting device, 14 is a boiling temperature setting device, 1
5 is an energization control device, 16 is a used heat amount calculation device, 1
7 is a water meter, 100A to 100N are hot water storage type electric water heaters, and 200 is a central control device. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A heating element that heats the water in the hot water storage tank using late-night electricity, a temperature detection means that detects the water supply temperature and boiling temperature in the hot water storage tank, and a temperature detection means that detects the amount of heat used for the amount of hot water used in the past few days. a storage device for storing actual results as data; a required heat setting device for setting the required amount of heat to be stored in the hot water storage tank based on the data; and a boiling temperature determined from the water supply temperature, required amount of heat, and hot water storage tank capacity. a boiling temperature setting device for setting the heating temperature; and a boiling temperature setting device for setting the temperature of the heating element; an energization control device that stops the energization, and calculates the actual amount of heat used relative to the amount of hot water used and inputs the value into the storage device as the latest data, and sets it as the oldest data among the data stored in the storage device. A group of multiple hot water storage type electric water heaters each equipped with a used heat amount calculation device that can be exchanged and updated data, and the electric power supplied to each hot water storage type electric water heater can be supplied throughout the late night power supply hours. A control device for a hot water storage type electric water heater, characterized in that a central control device is provided that distributes the start of energization according to the boiling temperature so as to have an even distribution.