JPS647300B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a control device for a hot water storage type electric water heater that uses late-night electricity, and is based on the user's hot water usage record and the next day's hot water boiling pattern input from an input device. Conventionally, the required amount of heat to be stored in the hot water storage tank was calculated using
The purpose is to enable users to use the capacity of a fixed hot water storage type electric water heater according to their needs.

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 time to start supplying late-night power comes, 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.

This invention attempts to eliminate these drawbacks, and stores in a storage device the amount of hot water used, for example, the amount of heat used in relation to the amount of hot water used over the past several days. It is updated by exchanging the data, that is, it has a learning function, so that the required amount of mixed hot water can always be obtained based on this data, and at the same time, the next day's boiling pattern can be input in advance. By adding an input device that allows boiling water to flow and controlling the required energization time to the heating element based on these conditions, the amount of remaining hot water is reduced and heat loss after boiling is eliminated as much as possible. be.

Hereinafter, one embodiment of the present invention will be described based on the overall configuration diagram in FIG. 3 and the control flowchart in FIG. 4.

In Fig. 3, symbols 1 to 5, 7, and 8 are the first
Figure 2 shows the same thing as Figure 2. 9 is a temperature detection means such as a thermistor (hereinafter referred to as a temperature sensor);
It continuously detects the temperature of water supplied into the hot water storage tank 1 from the water supply pipe 2, and also detects the temperature of boiling hot water, and is provided 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. In this example, it is closed at the same time as the time switch 8 is turned on, and is opened by operation of a control section, which will 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. Further, 18 is an input device.
Note that the water meter 17 may be provided on the hot water supply pipe 3 side.

The input device 18 may be used to input, for example, "take a bath" or the like.
The next day's boiling pattern, such as "no bathing", is selected from pre-prepared boiling patterns, and the storage device 12 calculates the amount of heat used by the calculation device 16 for each boiling pattern of the input device 18. The actual amount _of heat for the amount of hot water used for the past few days is stored as data. This data is set to a fixed number of days, such as 10 days, so that the latest data from the previous day is always stored and the oldest data is deleted.

The required heat amount setting device 13 is, for example, a storage device 12.
Then call the maximum value K _G max of the data classified and stored for each boiling pattern (in 10 days in the above example), and calculate the constant C (for example, the margin rate 10 % is 1.1)
The required amount of heat to be stored in hot water tank 1 is multiplied by
Ks (kcal) is calculated as Ks=K _G max×C.

The boiling temperature setting device 14 sets the required amount of heat Ks,
From the hot water storage tank capacity Vt () and water supply temperature Ti (℃),
Find the boiling temperature To (°C) from the formula below.

To=Ks/Vt+Ti The energization control device 15 controls turning off (opening) the switch 10, and is activated when the temperature sensor 9 detects the boiling temperature To.

The amount of heat used calculation device 16 calculates the amount of heat required for 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 previous day's boiling temperature is To (℃).
K _G is calculated as K _G =v×(To−Ti).

The input device 18 is used by the user to directly input the boiling water pattern for the next day. For example, since the amount of hot water used on bathing days and non-bathing days differs greatly, this is made into a pattern in advance so that it can be input on the previous day.

Next, the operation of the embodiment shown in FIG. 3 will be explained with reference to FIG. 4. Note that (1) to (13) in FIG. 4 represent each step.

The system starts (1), and at midnight, for example, 23:00, the time switch 8 is turned on (2), and the power supply 7 is supplied to the hot water storage type electric water heater. At the same time, control is started, and first, the amount of heat K _G for the amount of hot water used that day, which was used before midnight power was supplied to the electric water heater, is calculated by the amount of heat used calculation device 16. (3), this data is input to the storage device 12, and is replaced with the oldest data among the data previously stored in the storage device 12, thereby updating the data (4). Then, when the heating element 5 starts to be energized (5), the input device 18
In response to the input, the maximum K _G max of the corresponding pattern among the latest data classified and stored for each pattern in the storage device 12 is called (6), and the required heat amount setting device 13 sets a margin for K _G max. Set the required amount of heat Ks by multiplying the constant C by looking at the rate (7). In addition, in the boiling temperature setting device 14, the temperature sensor 9 measures the water supply temperature Ti in the hot water storage tank 1 (8), and the boiling temperature is determined from the hot water storage tank capacity Vt.
Calculate and set To (9). When the water temperature reaches the boiling temperature To thus set (10), the electricity to the heating element 5 is turned off (11). Then, at the end of the midnight power supply time, for example 7 o'clock, the time switch 8 is turned off (12) and the sequence is stopped (13).

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

As explained in detail above, the present invention stores the latest data on the amount of heat relative to the amount of hot water used as the results for the past several days in the storage device, and uses this data and input from the input device to determine the next day's boiling pattern. Since the required amount of heat to be stored in the hot water storage tank is determined based on the amount of heat required to be stored in the hot water storage tank, the amount of hot water that is required to be stored in the hot water storage tank can be obtained every day according to the actual situation of the user. This has the advantage of reducing heat dissipation loss after boiling and lowering maintenance costs.

[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 an overall configuration diagram showing an embodiment of the present invention, and FIG. 4 is a control flow chart thereof. 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, and 18 is an input device. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. In an electric water heater that heats water in a hot water storage tank by energizing a heating element using late-night electricity, a temperature detection means for detecting the temperature of water supplied to the hot water storage tank and the boiling temperature, and a temperature detection means for detecting the boiling temperature of the water the next day. an input device for inputting a raising pattern; a storage device for storing as data the actual amount of heat for the amount of hot water used in the past several days for each input pattern from the input device;
a required heat amount setting device that sets the required amount of heat to be stored in the hot water storage tank based on the data; a boiling temperature setting device that sets the boiling temperature from the water supply temperature, the required amount of heat, and the hot water storage tank capacity; an energization control device that stops energizing the heating element when the boiling temperature detected by the temperature detection means reaches the boiling temperature set by the boiling temperature setting device; A hot water storage type electric machine comprising: a used heat amount calculation device that inputs the value as the latest data into the storage device and updates the data by replacing it with the oldest data among the data stored in the storage device. Water heater control device.