JPS6316665B2 - - 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 is to reduce the amount of remaining hot water and heat loss after boiling by calculating the amount of water and controlling the start time of energization to the heating element so that the energization time is obtained at the same time as the end of the energization time of late-night electricity. do.

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 the figure, 1 is a hot water storage tank, 2 is a heating element, and 3
is an automatic temperature controller, 4 is a power supply, and 5 is a time switch for late-night power.
From 11pm to 7am the next morning.

Next, the function and operation will be explained.

When the midnight power supply start time arrives, the contact of the time switch 5 is closed and the supply of electricity to the heating element 2 is started. And the water temperature in hot water storage tank 1 is 85
When the temperature reaches [° C.], the contacts of the automatic temperature controller 3 are opened and the electricity supply to the heating element 2 is stopped.

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, and varies greatly from day to day and 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, it will boil up in a short time.

In addition, since the power supply to the heating elements 2 starts all at once at the time when the late-night power supply is applied, the power load is concentrated immediately after the power supply starts, and the equalization of the power load, which is the original purpose of the late-night power supply, is prevented. This results in poor power transmission efficiency, and the disadvantage is that the high temperature water heated in the hot water storage tank 1 is left unused for a long time, increasing heat loss due to natural heat radiation. was.

Furthermore, conventional hot water storage type electric water heaters are not equipped with a device for detecting the amount of heat of remaining hot water, and only some of them have been equipped with devices that detect the amount of remaining hot water.

However, this method of detecting the amount of remaining hot water was also a step-by-step method in which multiple temperature sensors, such as thermostats and thermistors, were lined up on the outer wall of the hot water storage tank to detect temperature changes at those locations.

For this reason, the detected amount of remaining hot water was not a very accurate value, and in many cases it was simply used as data for the next boiling.

The present invention aims to solve these drawbacks by making it possible to set the regular amount of hot water used and the temporary amount of hot water used in advance, and determining the amount of hot water remaining in the hot water storage tank based on the preset amount of hot water used the next day. Detects the amount of heat,
By calculating the required energization time to the heating element and controlling the start time of energization to the heating element so that the required energization time can be completed at the end of the midnight electricity supply, the amount of remaining hot water can be reduced and boiling can be achieved. The aim is to eliminate as much subsequent heat loss as possible.

The present invention will be explained below based on the energization control block diagram shown in FIG.

In Fig. 3, 6 is a constant hot water amount setting device for presetting the next day's regular amount of hot water stored in the hot water storage tank 1, and 7 is a provisional hot water amount setting device for presetting a one-time provisional hot water amount. This is a hot water amount setting device.

The steady hot water amount setting device 6 and the provisional hot water amount setting device 7
is a similar hot water amount setting device, but the former is a device that constantly sets the amount of boiling water and is generally intended for bathing where the amount of hot water used is relatively large, whereas the latter is for bathing where the amount of hot water used is relatively large. This is a device that is temporarily set when the amount of hot water used is extremely less than the normal case, or when no hot water is used at all. Normally, the steady hot water amount setting device 6 is operating, and the provisional hot water amount setting is performed in this state. Then, for one day only, the temporary hot water amount setting is given priority for boiling, and the next morning when boiling is complete, the provisional hot water amount setting is automatically canceled and the system returns to the steady water amount setting.

Reference numeral 8 denotes an arithmetic unit A that calculates the amount of heat of hot water to be stored in the hot water storage tank 1 from the setting value set by the steady water amount setting device 6 or the provisional hot water amount setting device 7.

Reference numeral 9 denotes a residual water heat amount detection device for stirring the inside of the hot water storage tank 1 and detecting the amount of remaining hot water from the temperature change at the bottom of the hot water storage tank 1 before and after the stirring; 10 refers to the arithmetic unit A8 and the remaining water heat amount detection device; Calculator B calculates the required energization time to the heating element 2 from the difference in the amount of heat detected in 9, and 11 calculates the required energization time to the heating element 2 to obtain the predetermined energization time determined by the calculator B10 at the end of the late-night power supply time. This is a timer device for controlling the start time of energization to the body 2.

Next, a concrete example of the operation of the above configuration will be explained using symbols and formulas. First, before entering the late-night power-on period, the user inputs the amount of hot water used for the next day. Here, if the amount of hot water used on the next day inputted by the user using the steady water amount setting device 6 or the temporary hot water amount setting device 7 is V (water temperature T [°C]), the calculator A8 calculates the following equation: K ₁ = (T-t)× Calculate V [Kcal] and calculate the calorific value of the amount of hot water that should be stored in the hot water storage tank 1 by the end of the late-night power supply time.
Calculate K ₁ [kcal].

Further, the residual hot water heat quantity detection device 9 detects the calorific value K ₂ [kcal] of the quantity of hot water remaining as residual hot water in the hot water storage tank 1, for example, by a method as described later.

Then, the calculator B10 calculates H=( _K1 - _K2 )/860×W [hr] based on K1 _{and K2} detected by the calculator A8 and the residual water heat amount detection device 9, Calorific value of the amount of hot water that should be stored in hot water storage tank 1 K ₁ to calorific value held by the remaining hot water K ₂
heating element 2 from the net amount of heat that should be applied after subtracting
The required energization time H [hr] is calculated.
(1KWH=860Kcal). Here, W represents the rated power consumption (KW) of the heating element 2. Then, the timer device 11 measures the time so that the required energization time H [hr] obtained by the calculator B10 is obtained at the end time of the late-night power energization time, and for example, the remaining time of the late-night power energization time period and the required energization time H[hr] are obtained. hr] becomes equal, the power supply to the heating element 2 is started, and the power supply is controlled so as to end at the same time as the end time of the late-night power supply time. Therefore, the heating element 2 is connected to the hot water storage tank 1.
The greater the amount of heat remaining in the hot water, the shorter the energizing time is required, and the hot water will not be left in the hot water storage tank 1 for a long time, so heat radiation loss can be reduced. Furthermore, since the hot water amount setting can be set as appropriate between a steady and temporary amount, seasonal changes can be handled by the steady hot water amount setting device 6, and large daily changes can be handled by the provisional hot water amount setting device 7. This reduces the amount of remaining hot water and reduces maintenance costs.

Next, the method for detecting the amount of remaining hot water _K2 is shown in Figures 4 to 6.
This will be explained using figures. FIG. 4 is a cross-sectional view of a hot water storage type electric water heater showing an example of the residual water heat amount detection means in the present invention, and FIGS. 5 and 6 are temperature distribution diagrams inside the hot water storage tank when detecting the amount of residual hot water.

In FIG. 4, 1 is a hot water storage tank, 12 is a temperature detector installed at the bottom of the hot water storage tank 1 to measure the temperature of hot water in the hot water storage tank 1, 13 is a water supply pipe, and 14
1 is a hot water supply pipe, and 15 is a faucet provided at the tip of this hot water supply pipe. Reference numeral 16 denotes a circulation pump as a stirring device, which is installed in the middle of a communication pipe 17 whose one end is connected to the lower part of the hot water storage tank 1 and the other end is connected to the middle of the hot water supply pipe 14. Water is circulated to the upper part of the hot water storage tank 1 through a part of the hot water storage tank 1.

In the above configuration, the residual hot water heat amount K ₂ can be detected as follows.

That is, as shown in FIG. 4, it is assumed that the hot water storage tank 1 is initially filled with hot water at T ₁ [°C]. FIG. 5 shows the temperature distribution inside the hot water storage tank 1 after using hot water of V ₁ [] from the faucet 15 in this state. That is, in this state, water of t [°C] flows into the lower part 1a of the hot water storage tank from the water supply pipe 13 by the amount of hot water used V ₁ [], and hot water of T ₁ [°C] flows into the upper part 1b of the hot water storage tank at V ₂ [°C]. ] It remains.
In this state, when the circulation pump 16 is operated with the faucet 15 closed, the water in the lower part 1a of the hot water storage tank flows from the upper part 1b of the hot water storage tank through the communication pipe 17 and stirs the hot water layer in the upper part 1b of the hot water storage tank. The water temperature will gradually average out.

In this way, the water temperature is averaged and the hot water tank 1
Figure 6 shows the temperature distribution of T ₂ [°C]. Therefore, if the total amount of the hot water storage tank 1 is V ₀ [ ] (eigenvalue V ₀ =V ₁ +V ₂ ), the temperature measured by the temperature detector 12 installed at the lower part 1a of the hot water storage tank before the operation of the circulation pump 16 is t [°C] , the measured temperature after the operation of the circulation pump 16 is T ₂ [°C], so the residual water heat value K ₂ [Kcal] can be calculated as follows.

K ₂ =V ₀ ×(T ₂ −t) [Kcal] In the above embodiment, the circulation pump 16 is used as a means for stirring the inside of the hot water storage tank 1, but other stirring means may be used. Of course, it is possible.

As described above, according to the present invention, there is a hot water amount setting that allows the amount of hot water used to be stored in the hot water storage tank to be appropriately selected between a constant amount and a temporary amount, so that the amount of hot water used can be adjusted according to daily or seasonal changes. You can freely set the settings to reduce the amount of hot water left each day. In addition, since the heating element is energized mainly during the latter half of the late-night power supply period, it is possible to eliminate the conventional drawback of the load being concentrated in the first half, improving power transmission efficiency, and dissipating heat after boiling. Loss is also reduced, and overall maintenance costs are lower. Furthermore, since the residual hot water heat amount can be detected as a continuous amount, the detection accuracy is high, and the calculation of the required energization time to the heating element has the effect of further increasing accuracy.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a hot water storage type electric water heater, Fig. 2 is a main electric circuit diagram of a conventional hot water storage type electric water heater, Fig. 3 is an energization control block diagram according to the present invention, and Fig. 4 is the remaining part of the present invention. FIGS. 5 and 6, which are cross-sectional views of a hot water storage type electric water heater showing an example of the hot water heat amount detection means, show temperature distribution charts inside the hot water storage tank when detecting the residual hot water heat amount. 1 is a hot water storage tank, 2 is a heating element, 6 is a steady hot water amount setting device, 7 is a temporary hot water amount setting device, 8 is a calculator A,
Reference numeral 9 indicates a residual water heat amount detection device, 10 indicates a computing unit B, 11 indicates a timer device, 12 indicates a temperature detector, 16 indicates a circulation pump (stirring device), and 17 indicates a communication pipe.

Claims (1)

[Claims] 1. A steady hot water amount setting means for presetting the constant amount of hot water used to be stored in the hot water storage tank, a provisional hot water amount setting means for presetting a temporary hot water amount for one-time use, and the steady hot water amount setting means or Temporary hot water amount setting means A calculating means for calculating the heat value of the amount of hot water to be stored from the set value set, and detecting temperature changes in the lower part of the hot water storage tank before and after operation of the stirring device that stirs the inside of the hot water storage tank. a residual water heat amount detection means for detecting the residual water heat amount, and a calculation means B for calculating the required energization time to the heating element from the difference in the heat amount detected by the calculation means A and the residual water heat amount detection means.
and a timer device for controlling the start time of energization to the heating element so that the required energization time determined by the calculation means B is obtained at the end time of the late-night power energization.