JPH028224B2 - - 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 is designed to direct the required energization time to be applied to the heating element based on the user's actual hot water usage record. In addition, the start of energization of the heating element is delayed after the start time of late-night power supply, so that the capacity of the conventionally fixed hot water storage type electric water heater can be used in accordance with the actual situation of the user. The purpose is 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 the automatic temperature controller stage, 7 is the power supply, and 8 is the time switch for late-night power, and the time when the power is on is generally
It is 8 hours from 11pm to 7am 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 information on the amount of hot water used in the storage device, for example, in the past.
The data on the amount of hot water used for 10 days is stored, and this data is updated every day according to the amount of hot water used that day.In other words, it has a learning function, and the heat generation is adjusted so that the required amount of mixed hot water is always obtained based on this data. In addition to calculating and controlling the required time for energization to the body, the start time of energization is delayed after the start time of late-night electricity supply, thereby reducing the amount of remaining hot water and eliminating heat loss after boiling as much as possible. It is something.

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, which is opened and closed by operation of a control section to be described later. Reference numeral 11 denotes the aforementioned control unit, which includes a storage device 12,
Energization time calculation device 13, boiling temperature setting device 1
4, an energization control device 15, and an energization time measuring device 16.

The storage device 12 stores the actual HG of several days of energization time measured by the energization time measuring device 16 as data. This data should be stored for a fixed number of days, such as 10 days, so that the latest data is always saved.

The energization time calculation device 13 includes, for example, the storage device 12
Call the maximum value HGmax among the data stored within it (in the above example, out of 10 days),
Multiply by a constant C based on the margin rate (for example, 1.1 if the margin rate is 10%) to calculate the energization time Hs (Hr) as Hs=HGmax×C.

The boiling temperature setting device 14 calculates the energization time Hs calculated by the energization time calculation device 13, the hot water storage tank capacity Vt(), the rated power consumption W (kw) of the heating element 5,
From the water supply temperature Ti (°C), calculate the boiling temperature To (°C) using the formula below.

To=Hs×W×860/Vt+Ti The energization control device 15 controls the on/off of the switch 10, and turns on the switch 10 after (8-Hs) hours from the start time of midnight power supply, and turns it off. This is performed when the temperature sensor 9 detects the boiling temperature To.

The energization time measuring device 16 measures the actual value of the energization time to the heating element 5 and inputs it to the storage device 12, and measures the time from when the energization control device 15 turns on the switch 10 to when it turns it off. This is the power-on time.

Next, the operation of the embodiment shown in FIG. 3 will be explained with reference to FIG. 4. Note that (1) to (15) in FIG. 4 represent each step.

It starts (1), and at midnight, for example, 11pm, the time switch 8 is turned on (2). First, the energization time measuring device 16 starts the measurement operation (3), and the maximum of the latest data is stored in the storage device 12.
Call HGmax(4).

Next, in the energization time calculation device 13,
Multiply HGmax by a constant C based on the margin rate to calculate the energization time.
Calculate Hs (5). On the other hand, in the boiling temperature setting device 14, the temperature sensor 9 measures the water supply temperature Ti in the hot water storage tank 1 (6), and the energization time Hs calculated by the energization time calculation device 13 and the water supply temperature Ti, The boiling temperature To is set from the hot water storage tank capacity Vt and the rated power consumption W of the heating element 5 (7). Next, after time switch 8 is turned on (8-Hs)
It is determined whether the time of
When the water temperature reaches To (10), the energization to the heating element 5 is turned off (11), the calculation of the energization time measuring device 16 is completed (12), and the actual energized HG is stored in the memory. 12 and update the data (13). In this case, if there is no hot water remaining in the hot water storage tank 1, the heating element 5
The energization off time matches the time switch 8 off time, but in reality they do not match because of residual hot water.

Furthermore, the late-night power supply time end time, for example, 7
When the time comes, time switch 8 turns off (14) and stops (15).

In addition, in the above embodiment, the energization time calculation device 13
In the calculation of the energization time Hs, the maximum HGmax among the data in the storage device 12 was used, but 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.

As explained in detail above, in this invention, the latest data on the energization time is stored in the storage device as past results, and the time to energize the heating element is determined based on this data. Since the amount of hot water that is available every day is based on the actual situation, the amount of remaining hot water is reduced.Also, since the start time of electricity supply to the heating element is shifted to later than the start time of late-night power supply, the boiling time is shorter than the late-night power supply time. This has the advantage of reducing heat dissipation loss after boiling up 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 an energization time calculation device, 14 is a boiling temperature setting device, 1
5 is an energization control device, and 16 is an energization time measuring 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 track record of energization time are provided. a storage device that stores data; an energization time calculation device that calculates the required energization time to the heating element based on the data; and the water supply temperature, the required energization time, the hot water storage tank capacity, and the rated consumption of the heating element. A boiling temperature setting device that sets the boiling temperature from electric power, and energizing the heating element later than the midnight power supply start time so that the required energization time determined by the energization time calculation device can be obtained during the midnight power supply time. an energization control device that starts energizing the heating element and stops energizing the heating element when the temperature detected by the temperature detection means reaches the boiling temperature set by the boiling temperature setting device; 1. A control device for a hot water storage type electric water heater, comprising: an energization time measuring device that measures time and inputs the value into the storage device to update the data.