JPH0338508B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a hot water storage type electric water heater. The purpose is to calculate the required energization time and control the energization so that it is energized at a predetermined time.

[Prior art]

A conventional hot water storage type electric water heater will be explained with reference to a schematic structural diagram in FIG. 1 and a main electric circuit diagram in FIG. 1
is a hot water storage tank, and a heating element 2 is attached to the lower part of the tank. 3 is an automatic temperature regulator for controlling the boiling temperature, and is attached to the lower wall surface of the hot water storage tank 1. 4 is a valve for taking out hot water boiling in the hot water storage tank 1 from a faucet, and 5 is a water supply pipe. In FIG. 2, 6 is a power source, and 7 is a time switch for setting the midnight power supply time.

Explain the action. The capacity of the heating element 2 is set so that the water can be boiled from approximately 8°C to a target temperature of 85°C within 8 hours of late-night power supply. Furthermore, the automatic temperature controller 3 is configured to open a contact and stop supplying electricity to the heating element 2 when the water in the hot water storage tank 1 reaches 85°C. is fulfilled.

However, the amount of hot water used is not always the same, and varies greatly from day to day, depending on the season. In particular, whether or not a person takes a bath is a factor that greatly influences the amount of hot water used, and on days when a person does not take a bath, more than half of the stored hot water may remain.

Therefore, if there is any remaining hot water, the electricity will start all at once when the electricity is turned on late at night, and the water will boil up in a short time. As a result, the power load is concentrated, making it impossible to equalize the power load, which is the original purpose of late-night power, resulting in poor power transmission efficiency, and the hot water that has been boiled cannot be used for a long time. This has the drawback of increasing heat radiation loss from the hot water storage tank.

[Summary of the invention]

This invention attempts to eliminate these conventional drawbacks, and it controls the boiling of only the appropriate amount of hot water based on the preset amount of hot water used the next day, the water supply water temperature, and the state of the remaining hot water in the hot water storage tank. The purpose is to calculate the time required for energization of the heating device and control the energization to be conducted at a predetermined time.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described based on the structural block diagram of FIG. 3 and the arithmetic unit block diagram of FIG. 4. In FIG. 3, 8 is a flow rate sensor installed in the middle of the water supply pipe 5, 9 is a closed circuit that communicates the upper and lower parts of the hot water storage tank 1, and a circulation pump 10 and a heating element 2 are installed in this closed circuit. A built-in heating device 11 is provided. 12 is a water supply water temperature sensor 12, 13a provided at the bottom of the hot water storage tank 1;
Reference numerals 13b and 13c are upper residual hot water temperature sensors provided at the upper part of the hot water storage tank 1, which are respectively provided in the vertical direction with a predetermined interval, and measure the water temperature in the hot water storage tank 1. Reference numeral 14 denotes a hot water amount setting device for presetting the amount of hot water to be used for the next day, and the set value is input to the calculation device 15 as data together with the detected values by the sensors 8, 12, 13a, 13b, and 13c. The calculation device 15 includes a required heat amount calculation section 20, a remaining hot water heat amount determination section 21, and a hot water amount calculation section 2 shown in FIG.
2. Circulation amount calculation unit 23, energization required time calculation unit 2
4. Consists of an energization start time calculation section 25.

The electric water heater control device is configured as described above, and first, the usage and function of the hot water amount setting device 14 will be explained.

This hot water amount setting device 14 allows the user to set the expected amount of hot water VI () and hot water temperature T (°C) for the next day in advance.
The expected amount of hot water to be used is obtained by mixing with water, and the suitable temperature for use is T (°C), which is generally in the range of 40°C to 45°C.

For example, the expected amount of hot water used at T = 45℃ VI
When ( ) is set in the hot water amount setting device 14 , the hot water amount setting device 14 outputs a data value corresponding to the set value to the required heat amount calculating section 20 of the arithmetic device 15 .

Now, enter the expected amount of hot water to be used for the next day into the hot water amount setting device 14 by inputting hot water at TI (°C) to VI (), inputting the detected value of the water supply water temperature sensor 12 to TW (°C), and inputting the detected value of the upper temperature sensor 13 to TZ (°C). ), and the detected value of the flow rate sensor 8 is VU(), and the operation of the arithmetic unit 15 will be explained using formulas. Here, the flow rate sensor 8 detects the amount of hot water used on that day from the full state after boiling. For example, a gear equipped with a Hall element for oscillating pulses is connected to This can be done by placing the flow rate in the path and detecting it as an integrated value by replacing the flow rate with a pulse. In this case, it is also necessary to return the integrated value to the zero value once a day immediately after the water boils.

When the time switch 7 is turned on and the power supply 6 is supplied, the required heat amount calculation unit 20 calculates the values input by the user to the hot water amount setting device 14, TI (°C), VI (), and the detected value of the water supply water temperature sensor 12. From TW (°C), the required amount of heat that must be stored in hot water storage tank 1
Calculate KI (Kcal). The calculation formula is as follows.

KI = VI (TI - TW) (kcal) On the other hand, the remaining hot water calorie determination unit 21 calculates the detected value TW (°C) of the feed water temperature sensor 12, the detected value TZ (°C) of the upper residual water temperature sensor 13c, and the flow rate sensor 8. Calorific value of the unused hot water (residual hot water) in the hot water storage tank 1 is calculated from the detected value VU (), and the calorific value of the remaining hot water KZ (Kcal)
is determined by the following formula.

KZ=KI′−VU×(TZ−TW) (Kcal) Here, KI′ is the required amount of heat generated on the previous day. In the above equation, it is difficult to accurately determine the amount of heat of the remaining water other than during heating by the heating element due to heat loss such as heat radiation after boiling is completed. Therefore,
The upper remaining hot water temperature sensor 13 corrects the amount of heat of the remaining hot water. For example, the upper remaining hot water temperature sensor 13
is installed at an arbitrary position determined in advance, and when the detected value of the sensor changes drastically due to the use of hot water, let the detected value be TZn (℃) and the amount of hot water above the sensor installation position be VZ (). The heat value of the remaining hot water is determined by the following formula.

KZn=VZ×(TZn−TW) (Kcal) Detection value of flow rate sensor 8 at that point VU()
When the detected value of the flow rate sensor 8 and the detected value of the upper residual hot water temperature sensor 13 are TZm (℃), the calorific value of the remaining hot water is KZm = KZn - (VUn - VU) (TZm −TW)
(Kcal), and by repeating this process, it becomes possible to more accurately detect the heat value of the remaining hot water.

Next, in order to satisfy the required heat amount KI (Kcal), the hot water amount calculation unit 22 calculates the amount of heat excluding the remaining heat amount KZ (Kcal) to a constant high temperature hot water of T0 (°C), for example 85 (°C).
It calculates the amount of hot water to be stored as
The amount of hot water V0 () that should be heated and stored to T0 (℃) is calculated using the following formula.

V0=(KI-KZm)/(T0-TW) () The circulation amount calculation unit 23 calculates the rated heat generation capacity W( KW.) heating element 2
The circulation amount Q0 (/Hr) of the circulation pump 10 corresponding to the water temperature TW°C when hot water is heated at T0 (°C) and stored in the upper part of the hot water storage tank 1 is calculated by the following formula.

Q0=(W×860×η)/(T0−TW)
(/Hr) Here, η is the heating efficiency to compensate for loss during heating and circulation.

Next, the energization time calculation unit 24 supplies hot water at T0 (°C).
The time required to operate the heating device 11 and the circulation pump 10 in order to store V0 ( ) is determined, and the required energization time H0 is determined by H0 = V0/Q0 (hours).

The energization start time calculation unit 25 determines in which time period among the late-night power supply hours the required energization time H0 required for boiling, calculated by the energization required time calculation unit 24, is to be distributed, that is, when the time switch 7 is ON.
The purpose is to find out how many hours after the start of energization. Now, we assume that the load is concentrated during the off-peak hours of the electricity load from 2:00 a.m. to 6:00 a.m., and that the late-night power supply time is 8 hours from 11:00 p.m. to 7:00 a.m. the next morning. explain. The setting of the energization start time HS needs to be divided into the following three cases.

(1) When H0≧8, HS=0.

If the required time for energization (H0) is equal to or greater than 8 hours, naturally energization is started at the same time as the time switch 7 is turned on.

(2) When 8>H0≧6, HS=(8-H0).

Power is not turned on during the first half of the late-night power supply period and is shifted to the second half. Since the OFF time of the time switch 7 and the boiling time match, there will always be a load during off-peak hours.

(3) When 6>H0, set HS=(5-H0/2).

There are 5 hours between 23:00 when the time switch 7 is ON and 4:00 a.m., which is the central time of off-peak (from 2:00 a.m. to 6:00 a.m.), and the load is distributed around 4:00 a.m.

The energization start time calculation unit 25 distributes the load during the off-peak hours of the power load as described above.

The pump control device 16 controls the flow rate of the circulation pump 10 based on the calculation result of the circulation amount calculation section 23. The energization control device 17 includes the energization start time calculation section 25 and the energization required time calculation section 24.
It controls the energization time of the heating element 2 and the circulation pump 10 based on the calculation results, and starts energization after HS time after the time switch 7 is turned on.
When the energization time of H0 time is secured, the energization is stopped.

FIG. 5 is a circuit diagram of a microcomputer in which the arithmetic unit 15 is implemented and its peripheral circuitry.
In the figure, 26 is a microcomputer in the control circuit, including a CPU 27, a memory 28, an input circuit 29,
an analog multiplexer 32 to which signals from the output circuit 30, internal timer 31, flow rate sensor 8, upper remaining hot water temperature sensor 13, water supply temperature sensor 12, hot water amount setting device 14, and time switch 7 are input;
It has an A/D converter 33 that digitally converts the output. The energization control device 17 is composed of a relay, and is connected to the output circuit 30 of the microcomputer 26.
is controlled by the output signal of Pump control device 1
6 is composed of a triax, and the output signal to the energization control device 17 of the microcomputer 26 is ON.
It is controlled by the output signal of the output circuit 30 in this state.

Next, the operation of the above embodiment will be explained with reference to FIG. FIG. 6 is a flowchart showing the control of the heating device 11 and the circulation pump 10 and the correction of the heat amount of the remaining hot water stored in the memory 28 of the microcomputer 26. First, at the same time as turning on the power supply 6, check whether the time switch 7 is ON or OFF (step 34). If the time switch 7 is OFF and the power supply 6 is not supplied, the remaining water heat amount correction flow is entered.
It is checked in step 35 whether there is already residual hot water at the mounting position of the upper residual hot water temperature sensor 13a, and if so, it is checked in step 36 whether there is still residual hot water present. If it is determined in step 36, the process returns to step 34. If it is determined in step 36 that there is no difference, the residual hot water heat quantity KZ is corrected in step 37, and the process returns to step 34 for confirmation. If it is determined in step 35 that there is no remaining hot water, it is determined in step 3 whether there is already residual hot water at the installation position of the residual hot water temperature sensor 13b.
8, and if there is, it is checked in step 39 whether or not there is still hot water left. If it is determined in step 39, the process returns to step 34. If it is determined in step 39 that there is no difference, the remaining hot water heat quantity KZ is corrected in step 40, and the process returns to step 34. If it is determined in step 38 that there is no remaining hot water, it is determined in step 4 whether there is already residual hot water at the installation position of the residual hot water temperature sensor 13c.
1, and if there is, it is checked in step 42 whether or not there is still hot water left. If it is determined in step 42, the process returns to step 34. If it is determined in step 42 that there is no difference, the remaining hot water heat quantity KZ is corrected in step 43, and the process returns to step 34.
Time switch 7 is turned on in step 34 above.
However, when the power supply 6 is supplied, the internal timer 31 within the microcomputer 26 starts (step 44). The hot water amount setting device 14 and each sensor 8, 13, 12 set the hot water amount setting value TI (℃), VI
(), water supply temperature TW (℃), upper residual hot water temperature TZ (℃),
The flow rate VU() is detected (step 45). Based on these detected values, the calculation device 15 calculates the circulation amount Q0,
The required energization time H0 and the energization start time HS are calculated (step 46). In step 47, the internal timer 31 monitors whether the HS time, which is the power supply start time, has elapsed since the time switch 7 was turned on.
In step 48, the pump control device 16 is adjusted so that the circulation amount Q0 calculated in step 46 is achieved.
control. In step 49, the heating device 11 and circulation pump 10 are turned on, and in step 50, the internal timer 31 monitors whether the time (HS+H0) has elapsed since the time switch 7 was turned on, and when it has elapsed, the heating device 11 and circulation pump 10 are turned on. OFF51. Thereafter, eight hours of midnight power supply time have passed, and the time switch 7 is turned off.

〔Effect of the invention〕

As described above, the present invention includes a hot water amount setting means for setting the expected amount of hot water to be used and the hot water temperature for the next day, a water supply temperature sensor for detecting the temperature of water supplied to the hot water storage tank, and a water supply temperature sensor for detecting the temperature of the water supplied to the hot water storage tank. An upper residual hot water temperature sensor for detecting the hot water temperature, a flow rate sensor for detecting the amount of hot water used, and a set value set by the hot water amount setting means and the detection value of each of the above sensors to determine when to store hot water at a predetermined amount. calculation means for calculating the appropriate circulation amount, the required energization time required for boiling, and the appropriate energization start time for placing the load in a predetermined time period; a pump control means for controlling the pump; and an energization control for controlling the heating device and the circulation pump to start operating when the energization start time calculated by the calculation means is reached and to stop the operation when the energization required time has elapsed. The hot water storage tank is equipped with a means to detect the temperature of water supplied to the hot water storage tank, the amount of hot water remaining, and the temperature of the remaining hot water, calculate the required amount of heat, calculate the required amount of hot water from this amount of heat, and store it from the top of the hot water storage tank. Unnecessary hot water is no longer left unused for long periods of time, reducing heat loss and lowering maintenance costs. In addition, since the power supply time can be predicted, it can be distributed during off-peak hours, which can be expected to improve the efficiency of power operation.

[Brief explanation of the drawing]

Figures 1 and 2 show a conventional hot water storage type electric water heater. Figure 1 is a schematic structural diagram, Figure 2 is a main electric circuit diagram, and Figures 3 to 6 are one example of the present invention. This shows an example. Figure 3 is a structural block diagram, Figure 4 is a structural block diagram, and Figure 4 is a structural block diagram.
The figure is the calculation block diagram, Figure 5 is the main circuit diagram, and Figure 6 is the main circuit diagram.
The figure is an operation flowchart. 1 is a hot water storage tank, 2 is a heating element, 8 is a flow rate sensor, 10 is a circulation pump, 11 is a heating device, 12 is a water supply temperature sensor, 13 is an upper remaining hot water temperature sensor, 14 is a hot water amount setting device, 15 is a calculation device, 16
1 is a pump control device, and 17 is an energization control device.

Claims (1)

[Claims] 1. Hot water flow rate setting for setting the scheduled amount of hot water to be used and hot water temperature for the next day in an electric water heater installed in the middle of a piping circuit that connects a circulation pump and a heating device to the upper and lower parts of a hot water storage tank. means, a water supply temperature sensor for detecting the temperature of water supplied to the hot water storage tank, an upper temperature sensor for detecting the temperature of hot water at the upper part of the hot water storage tank, a flow rate sensor for detecting the amount of hot water used in the hot water storage tank, and the hot water amount setting. Based on the setting value set by the means and the detection value of each sensor, the circulation amount when storing the water at a predetermined temperature, the required energization time for boiling, and the appropriate energization start time to place the load in a predetermined time zone. a calculation means for calculating, a pump control means for controlling the circulation pump so that the circulation amount calculated by the calculation means is obtained, and a pump control means for operating the heating device and the circulation pump when the energization start time calculated by the calculation means is reached. 1. A control device for an electric water heater, comprising: energization control means for controlling the operation so as to start the operation and stop the operation after the required energization time has elapsed. 2. The calculation means calculates the remaining hot water heat amount in the hot water storage tank from the detected values of the upper residual hot water temperature sensor and the flow rate sensor, and the residual hot water amount based on the detected value of the upper residual hot water temperature sensor attached to the wall surface of the hot water storage tank. The control device for an electric water heater according to claim 1, further comprising a residual water heat amount determining section having a function of correcting the hot water heat amount. 3. The control device for an electric water heater according to claim 1, wherein the calculation means is implemented by a microcomputer.