JPS6316660B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a hot water storage type electric water heater that utilizes late-night electricity, and the present invention is based on understanding the supplied water temperature and remaining hot water thermal calories.
Heat loss can be reduced by calculating the energization time to be applied to the heating element for a preset amount of hot water used, and by controlling the start time of energization to the heating element so that the energization time ends at the same time as the midnight energization time ends. The aim is to provide less equipment.

Figure 1 shows the main power supply circuit of a conventional hot water storage type electric water heater that uses late-night electricity. In the figure, 1 is a power source, and 2 is a time switch for late-night power, and the power-on period is generally from 11:00 PM to 7:00 AM the next morning. 3 is a heating element, and the capacity of the heating element is set so that water from around 8 [°C], which corresponds to the water temperature in winter, can be boiled to 85 [°C] within the time period when electricity is applied. 4 is an automatic temperature regulator, which has a normally closed contact and opens when the temperature of the hot water in the hot water storage tank reaches 85 [°C].

Next, the function and operation will be explained. At the midnight energization start time, the contact of the time switch 2 is closed and energization to the heating element 3 is started. When the temperature of the hot water in the hot water storage tank reaches 85 [° C.], the contacts of the automatic temperature controller 4 are opened and the electricity to the heating element 3 is stopped.

When boiling is finished, the automatic temperature regulator 4 repeatedly opens and closes the contacts to compensate for the temperature drop due to natural heat radiation, and energizes the heating element 3 as appropriate to maintain the water temperature at 85 [℃]. .

In this way, the entire amount of stored hot water is boiled to 85 degrees Celsius every morning.

However, the amount of hot water used is not always the same.
It varies from day to day and largely from season to 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. Additionally, depending on the season, the temperature of the water supply has a large effect on the amount of hot water that can be extracted, and in the summer when the temperature of the water supply is high, a larger amount of hot water can be extracted than in the winter. However, 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, so there is a lot of hot water left over in the summer.

In this way, boiling more water than necessary or leaving boiled hot water unused for a long time not only leads to a waste of electricity, but also
The disadvantage is that heat loss increases due to natural heat radiation from the hot water storage tank and heat radiation from hot water stagnant in the pipes.

Therefore, in order to eliminate the above-mentioned drawbacks, the same applicant previously proposed Japanese Patent Application Laid-open No. 75662/1983.

The present invention is an earlier application filed by the same applicant, published in Japanese Unexamined Patent Publication No. 58
-75662 has been further improved, and the required energization time required for boiling is calculated based on the supplied water temperature and the detected value of the amount of hot water and heat calories in the storage tank, based on the preset amount of hot water used the next day. , by controlling the start time of energization to the heating element so that the required energization time can be completed by the time when energization ends in the middle of the night, thereby eliminating unnecessary boiling and reducing heat dissipation loss after boiling. It is.

The present invention will be explained below based on the block diagram shown in FIG. In FIG. 2, reference numeral 5 indicates a hot water amount setting means for presetting the amount of hot water to be used on the next day stored in the hot water storage tank, 6 is a water supply water temperature sensor for detecting the temperature of water supplied to the hot water storage tank, and 7 is the hot water amount setting means. Calculator A calculates the thermal calories to be stored from the set value set in step 5 and the water supply temperature detected by the water supply temperature sensor. 8 is a residual water heat amount detection means for detecting the remaining water heat calorie by detecting the lower temperature of the hot water storage tank before and after the operation of the stirring device that stirs the inside of the hot water storage tank, and 9 is the heat calorie calculated by the calculator A7. Calculator B calculates the required energization time from the difference between the residual water heat calorie detected by the residual water heat amount detection means 8, and 10 is a calculation unit B that calculates the required energization time from the difference between the residual water heat calorie and the residual water heat calorie detected by the residual water heat amount detection means 8, and 10 obtains the predetermined energization time determined by the calculator B9 at the midnight energization end time. This is a timer device for controlling the start time of energizing the heating element 11.

Next, the specific structure of the residual water heat amount detection means 8 and the method for detecting the residual water heat calorie will be explained with reference to FIGS. 3 to 5.

Figure 3 is a cross-sectional view of the structure of a hot water storage type electric water heater;
Figure 5 and Figure 5 show temperature distribution charts inside the hot water storage tank. In FIG. 3, 101 is a hot water storage tank, 102 is a temperature detector installed at the bottom of the hot water storage tank 101 to measure the temperature of hot water in the hot water storage tank 101, 103 is a water supply pipe, 104 is a hot water supply pipe, 10
5 is a faucet provided at the tip of the hot water supply pipe 104.

106 is a circulation pump as a stirring device;
One end is attached to the bottom of the hot water storage tank 101, and the other end is attached to the hot water supply pipe 1.
The hot water supply pipe 104 is provided in the middle of the communication pipe 107 connected to the middle of the hot water storage tank 101.
Direct the water toward the connection.

In the above configuration, a method of detecting the remaining hot water heat calorie will be explained next. First, the hot water storage tank 101 is initially filled with hot water at a temperature of t ₁ (°C) (the third
condition). In this state, V ₁ () from faucet 105
Hot water storage tank 101 after hot water has been taken out and used
The internal temperature distribution is as shown in Figure 4.

In other words, the remaining hot water tank lower part 101a receives the same amount of hot water from the water supply pipe 103 as the used hot water amount V ₁ ().
Water with a temperature of t ₂ (℃) flows into the upper part of the hot water storage tank.
There remains V ₂ () of hot water at temperature t ₁ (°C) in 01b. In this state, if the circulation pump 106 is operated for a certain period of time with the faucet 105 closed,
Water in the lower part 101a of the hot water storage tank passes from the communication pipe Y107 through a part of the hot water supply pipe 104 to the upper part 1 of the hot water storage tank.
Since the hot water flows into the hot water storage tank 101b and stirs the hot water layer in the upper part 101b of the hot water storage tank, the temperature of the hot water in the hot water storage tank 101 gradually becomes average. FIG. 5 shows the averaged temperature distribution inside the hot water storage tank 101 after stirring in this way, which is the average temperature at t ₃ (° C.).

Therefore, the remaining hot water heat calorie can be obtained by performing the following calculation. First, hot water tank 101
When the total capacity of is V ₃ () (eigenvalue V ₃ = V ₁ + V ₂ ), the temperature measured before the operation of the circulation pump 106 by the temperature detector 102 installed in the lower part 101a of the hot water storage tank is t ₂ (°C), The measured temperature after operation of the pump 106 is t ₃ (℃), and the remaining hot water thermal calorie K ₂ (Kcal)
can be calculated using the following formula.

K ₂ = V ₃ × (t ₃ − t ₂ ) [Kcal] The above-mentioned detection of the residual hot water heat calorie K ₂ is performed before entering the late-night power-on time period, but even if it is performed immediately after the Detection is possible.

Next, the energization control operation of the heating element will be explained. Here, the amount of hot water used the next day is V() (hot water temperature T ₁
℃) is input into the hot water amount setting means 5, and the detected value t of the water supply water temperature sensor 6 immediately after entering the late-night power-on period is input.
(° C.), the calculator A7 calculates the thermal calorie _K1 that should be stored in the hot water storage tank 101 by the end time of the late-night energization period by executing the calculation of the following equation.

K ₁ =(T ₁ -t)×V [Kcal] Then, the calculator B9 calculates the residual water heat calories detected by the residual water heat amount detection means 8 from the heat calories K ₁ calculated by the calculator A7. The required energization time H of the heating element 11 is calculated from the net thermal calories to be applied excluding K ₂ by executing the following calculation.

H=K ₁ −K ₂ /860×W [hr] Here, W represents the rated power consumption (KW) of the heating element 11, and 1KWH=860 [Kcal].

Based on the above calculation results, the timer device 10
is the required energization time H calculated by the calculator B9 by counting the time at the same time as the midnight energization time starts.
When the remaining time of the late-night energization time becomes equal, energization of the heating element 11 is started. As a result, the power supply to the heating element 11 is stopped at the same time as the end of the late night power supply time, and hot water is heated to a predetermined temperature in the hot water storage tank 101.

As described above, the device according to the present invention is equipped with a hot water amount setting means that can set the amount of hot water used and boils only the amount of hot water required by the user, so the amount of remaining hot water is reduced every day, and the boiling starts at the end of the night when electricity is turned on. As a result, various heat radiation losses are reduced.
Further, since the heating element is energized during the latter half of the late-night energization time period, the peak of the power load in the first half of the energization time period can be alleviated, and power transmission efficiency can also be improved. Furthermore, since the residual water heat calorie is detected as a continuous amount rather than as a step-by-step detection value as in the past, it is possible to more accurately calculate the required energization time to the heating element, making maintenance easier. It also has the effect of reducing costs.

[Brief explanation of the drawing]

Fig. 1 is a main electrical circuit diagram of a conventional hot water storage type electric water heater, Fig. 2 is a block diagram of energization control according to the present invention, and Figs. 3 to 5 are diagrams for explaining an example of a residual water heat amount detection means. FIG. 3 is a structural sectional view of the hot water storage type electric water heater, and FIGS. 4 and 5 are temperature distribution diagrams inside the hot water storage tank before and after stirring. In the figure, 5 is a residual hot water setting means, 6 is a water supply water temperature sensor, 8 is a residual water heat amount detecting means, 7 and 9 are computing units, 1
0 is a timer device, 11 is a heating element, 101 is a hot water storage tank, 102 is a temperature detector, 106 is a circulation pump, and 107 is a communication pipe.

Claims (1)

[Claims] 1. A hot water amount setting means for presetting the amount of hot water used to be stored in the hot water storage tank, a water supply temperature detection means for detecting the temperature of water supplied to the hot water storage tank, and a set value set by the hot water amount setting means and a detection means for the water supply temperature detection means. Calculating means A calculates the thermal calories of the amount of hot water to be stored from the supplied water temperature, and the remaining hot water thermal calories are detected by detecting the temperature at the lower part of the hot water storage tank before and after operation of a stirring device that stirs the inside of the hot water storage tank. a calculation means B which calculates the required energization time from the difference between the heat calories calculated by the calculation means A and the residual water heat calories detected by the residual water heat detection means; A hot water storage type electric water heater comprising a timer device for controlling the start time of energization to the heating element so that the required energization time determined by calculation means B is obtained at the midnight energization end time.