JPH026981B2 - - 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 utilizes late-night electricity. The purpose of this system is to calculate the required amount of heat that should be stored in the water heater, thereby making it possible to use the conventionally fixed capacity of a hot water storage type electric water heater in accordance with the actual situation of the user.

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 amount of hot water is maintained at 85°C by opening and closing the automatic temperature controller 6, and in this way, the entire amount of stored hot water is boiled 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 generally constant throughout the year, or in fact, 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 capacity due to reasons such as 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 Ti 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 amount of hot water used for 10 days is stored as heat value data,
This data is updated every day based on the amount of hot water used that day, that is, it has a learning function.Based on this data, the required time for energizing the heating element is calculated so that the required amount of mixed hot water is always obtained. By controlling the power supply to the body to be leveled over the entire period from the start of the late-night power supply until the end of the supply, the amount of remaining hot water is reduced and heat loss after boiling is eliminated as much as possible. This is how it was done.

Hereinafter, one embodiment of the present invention will be described based on the configuration diagram of FIG. 3.

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 when the time switch 8 is turned on, and is opened by the 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 calculation device 13, an energization rate control device 14, a used heat amount calculation device 15, and an energization control device 16. 17
is a water meter installed in the water supply pipe 2, which is connected to the hot water storage tank 1.
Measure the water supply flow rate to. For this purpose, for example, an encoder is attached to a metering propeller that rotates in accordance with the flow rate to generate a number of pulses in accordance with the flow rate. Note that the water meter 17 may be provided on the hot water supply pipe 3 side. 18 is an input device.

The storage device 12 stores the heat amount of the used hot water calculated by the used heat amount calculating device 15 as an actual product KG for several days.
is stored 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 arithmetic unit 13 calls, for example, the maximum value KGmax of the data stored therein (for 10 days in the above example) from the storage device 12, and calculates a constant C (for example, a margin rate of 10%) based on the margin rate. 1.1) to calculate the required amount of heat Ks (Kcal) to be stored in the hot water storage tank 1 as Ks=KGmax×C.

Furthermore, the arithmetic unit 13 calculates the hot water storage tank capacity Vt
(), required amount of heat Ks (kcal), and water supply temperature Ti
(°C), calculate the boiling temperature To (°C) using the formula below.

To=Ks/Vt+Ti Furthermore, the arithmetic unit 13 calculates the energizing power Q of the heating element 5.
(KW). In other words, since the late-night power supply period is 8 hours, Q=Ks/8×860.

The energization rate control device 14 controls the power to the heating element 5 so that the energization power Q (KW) obtained by the arithmetic device 13 is obtained. This is done by using, for example, a triax and controlling the phase of its gate.

The amount of heat used calculation device 15 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 water supply is Ti (℃), and the previous day's boiling temperature is To (℃).
Find KG as KG=v×(To−Ti).

The energization control device 16 turns off the switch 10 when the temperature detected by the temperature sensor 9 reaches the boiling temperature To.

The input device 18 is used to select the next day's hot water usage schedule, such as "bath" or "no bath", from among previously prepared control patterns. That is, in the storage device 12, actual data for the past 10 days is stored for each pattern, ``taking a bath'' and ``not taking a bath.''
If this pattern is input from the input device 18, the performance data for "taking a bath" in the storage device 12 is selected, and among these, for example, the maximum performance data is used to calculate the required amount of heat, as will be described later.

Next, the operation of the embodiment shown in FIG. 3 will be explained with reference to FIG. 4. Note that (1) to (14) in FIG. 4 represent each step.

When you start (1) and finish using the hot water for the day,
That is, before midnight power is supplied to the electric water heater, the amount of heat KG used for the amount of hot water used that day is determined by the amount of heat used calculation device 15 (2), and this data is input into the storage device 12 and stored in advance. The stored data is updated (3).

Therefore, at midnight, for example at 23:00, the time switch 8 is turned on (4). When control is started at the same time as this energization, first, the largest KGmax of the latest data is called from the storage device 12 (5),
In the arithmetic unit 13, the required amount of heat Ks is set by multiplying KGmax by a constant C based on the margin rate (6). Also,
At the same time, the temperature sensor 9 measures the water supply temperature Ti in the hot water storage tank 1 (7), and furthermore, the arithmetic unit 13
Find the energizing power Q (KW) at , then calculate and set the boiling temperature To from the energizing time Hs, water supply temperature Ti, hot water storage tank capacity Vt, and required heat amount Ks.
(8).

When the data of the energized power Q (KW) obtained in this way is inputted to the energization rate control device 14, the average power per unit time supplied to the heating element 5 during the late night power supply time is calculated and energized. The rate is determined (9), and the heating element 5 is energized (10). When the amount of hot water reaches the preset boiling temperature To (11), the energization control device 16 operates and the switch 10 is activated.
is turned off to turn off the power to the heating element 5 (12).

Furthermore, the late-night power supply time end time, for example, 7
When the time comes, the time switch 8 is turned off (13) and the sequence is stopped (14).

In addition, in the above embodiment, in the calculation of the required amount of heat Ks in the arithmetic unit 13, among the data in the storage device 12,
Although the maximum KGmax was used, 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, the present invention stores the latest data on the amount of heat for the amount of hot water used as past actual results in the storage device, and based on this data and data on the amount of water scheduled to be used for the next day from the input device. The amount of electricity supplied to the heating element is determined, and the electricity supply is leveled out over the entire late-night electricity supply band, so the amount of hot water that is matched to the user's actual situation can be obtained every day. , combined with the use of the input device, the amount of remaining hot water decreases, and therefore,
Heat loss after boiling is reduced and maintenance costs are reduced. The data in the storage device is updated every time. In other words, since it has a learning function, it has the advantage of being able to adequately respond to the daily changing amount of hot water used.

[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 calculation device, 14 is an energization rate control device, 15 is a used heat amount calculation device, 16 is an energization control device, 17 is a water meter, 1
8 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 uses late-night electricity to energize a heating element to heat water in a hot water storage tank, an input device that selects and inputs the expected usage amount for the next day from among multiple patterns and a past multiple days a storage device that stores the actual amount of hot water used as heat amount data for each pattern; and a storage device that stores the actual amount of hot water used in the hot water storage tank as heat amount data based on the actual amount data in the storage device that corresponds to the pattern input from the input device. an arithmetic device that calculates the required amount of heat to be stored and the power to be applied to the heating element; an energization rate control device that averages and supplies the power during the late night power supply time; and a calculation device that calculates the amount of heat used and calculates the value. A control device for a hot water storage type electric water heater, comprising: a used heat amount calculation device that inputs data into the storage device and updates the data.