JPS6316666B2 - - 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, which grasps the water supply temperature and the amount of heat remaining in the hot water and applies it to the heating element for a preset amount of hot water used. To reduce the amount of remaining hot water and heat loss after boiling by calculating the required energization time 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. It is an object.

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 opened and the supply of electricity to the heating element 2 is started. and,
When the temperature of the hot water in the hot water storage tank 1 reaches 85 [° C.], the contacts of the automatic temperature controller 3 are opened and the electricity to the heating element 2 is stopped. In this way, the entire amount of hot water is stored every morning.
It's boiling to 85 degrees Celsius.

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 use of hot water, 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 water supply temperature is high, a larger amount of hot water can be extracted at the appropriate temperature than in the winter.

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 because the water is used at a lower temperature in the summer, and the hot water temperature in the summer is higher. Therefore, if the water is hot enough, it will boil 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 is applied, the power load is concentrated immediately after the power supply starts, and the original purpose of the late-night power is to equalize the power load. This has the disadvantage that the high temperature water heated in the hot water storage tank 1 is left unused for a long time, and heat loss due to natural heat dissipation increases. Ta.

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 adjusting the water supply temperature and the temperature in the hot water storage tank based on the preset amount of hot water used the next day. Calculating the required energization time to the heating element with reference to the detected value of the residual water heat value, and controlling the time to start energizing the heating element so that the required energization time can be completed at the time when the late-night power supply ends. This aims to reduce the amount of remaining hot water and eliminate heat loss after boiling as much 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, which uses a relatively large amount of hot water, whereas the latter is for non-bathing. This is a device that is temporarily set when the amount of hot water used is extremely less than the normal case, or when there is no plan to use hot water at all.Normally, the steady water amount setting device 6 is operating, and the temporary Once you set the hot water volume, the temporary hot water volume setting will be given priority for one day, and the next morning when boiling is complete, the provisional water volume setting will be automatically canceled and the system will return to the steady water volume setting.

Reference numeral 8 denotes a water supply temperature sensor for detecting the temperature of water supplied to the hot water storage tank 1, and reference numeral 9 denotes a temperature sensor for detecting the temperature of water supplied to the hot water storage tank 1; This is a calculator A that calculates the amount of heat of hot water that should be stored in the hot water storage tank 1.

Reference numeral 10 denotes a residual water heat amount detection device for stirring the inside of the hot water storage tank 1 and detecting the remaining water heat amount from the temperature change at the lower part of the hot water storage tank 1 before and after the stirring;
Reference numeral 1 denotes a calculator B for calculating the required energization time to the heating element 2 from the difference in the amount of heat determined by the calculator A9 and the remaining water heat amount detection device 10, and 12 is a calculator B that calculates the required time for energizing the heating element 2. This is a timer device for controlling energization to the heating element 2 so that the required energization time determined in B11 is obtained.

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, let us assume that the amount of hot water used on the next day inputted by the user using the steady hot water amount setting device 6 or temporary hot water amount setting device 7 is V [ ] (hot water temperature T [°C]), and the water supply temperature sensor 8 immediately after entering the late night power supply time period is The detected value is t
[°C], the calculator A9 calculates K ₁ = (T-t) x V (Kcal) to 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 remaining hot water calorie detection device 10 calculates the calorie K ₂ [Kcal] of the amount of hot water remaining as residual hot water in the hot water storage tank 1, for example, by a method described later.

Then, the computing unit B11 calculates H=(K ₁ - K ₂ )/860×W (hr) based on the K ₁ and K ₂ determined by the computing unit A 9 and the residual water heat amount detection device 10, and stores the hot water. Calorific value of the amount of hot water that should be stored in 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.
(1KW=960Kcal). Here, W represents the rated power consumption (KW) of the heating element 2.

Then, the timer device 12 calculates the required energization time H [hr] calculated by the arithmetic unit B11 at the midnight power end time.
For example, when the remaining time of the late-night power supply period and the required power-on time H [hr] become equal, the power supply to the heating element 2 is started, and the end time of the late-night power supply time is determined. At the same time, the energization is controlled to end.

Therefore, the more heat the remaining hot water in the hot water storage tank 1 has, and the higher the temperature of the supplied water, the shorter the time required for the heating element 2 to be energized. , which can reduce heat radiation loss.

Furthermore, the hot water amount setting can be set as appropriate between a steady and provisional setting, so 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 will reduce the amount of hot water remaining and reduce maintenance costs.

Next, the method for detecting the residual water heat value K ₂ is shown in Figures 4 to 6.
This will be explained using figures.

FIG. 4 is a sectional view of a hot water storage type electric water heater showing an example of the residual water heat amount detection means in this invention, and FIGS. 5 and 6 are temperature distribution charts inside the hot water storage tank when detecting the residual water heat amount. .

In FIG. 4, 1 is a hot water storage tank, 13 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, 14 is a water supply pipe, and 15
1 is a hot water supply pipe, and 16 is a faucet provided at the tip of this hot water supply pipe.

Reference numeral 17 denotes a circulation pump as a stirring device, which is installed in the middle of a communication pipe 18 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 15. The hot water is circulated through a part of the hot water supply pipe 15 to the upper 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 the faucet 16 is opened in this state and hot water of V ₁ [] is used.

That is, in this state, the lower part 1a of the hot water storage tank is filled with water from the water supply pipe 14 for the amount of hot water V ₁ [] used.
[°C] Water flows in, and the upper part 1b of the hot water storage tank has T ₁
There is still V ₂ [℃] hot water left. In this state, when the circulation pump 17 is operated with the faucet 16 closed, the water in the lower part 1a of the hot water storage tank flows into the communication pipe 18.
Since the hot water flows from the upper part 1b of the hot water storage tank through the hot water storage tank and stirs the hot water layer in the upper part 1b of the hot water storage tank, the temperature of the hot water gradually becomes average.

FIG. 6 shows the temperature distribution of the hot water storage tank 1 in which the hot water temperature is averaged in this way, and the average temperature is 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 ), then the lower part of the hot water storage tank 1a
The temperature measured by the temperature detector 13 installed before the operation of the circulation pump 17 is t [°C], and the temperature measured after the operation of the circulation pump 17 is T ₂ [°C], so the residual water heat value K ₂ can be calculated as follows.

K ₂ =V ₀ ×(T ₂ −t) [Kcal] In the above embodiment, the circulation pump 17 is used as a means for stirring the inside of the hot water storage tank 1, but other stirring means may also be used. Of course, it is possible.

As described above, according to the present invention, since the hot water temperature setting means is provided which can appropriately select and set the amount of hot water used to be stored in the hot water storage tank between a constant amount and a temporary amount, the amount of hot water used can be adjusted daily and seasonally. It can be set freely in response to changes in water, reducing the amount of remaining hot water 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 water heat value can be detected as a continuous amount, the detection accuracy is high, and changes in the water supply temperature are also taken into account, which has the effect of further increasing the accuracy of calculating the required energization time to the heating element. have

[Brief explanation of the drawing]

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 energization control block diagram according to the present invention, and Fig. 4 is a hot water storage type electric water heater showing an example of the residual water heat amount detection means according to the present invention. The sectional view, FIGS. 5 and 6 show temperature distribution charts inside the hot water storage tank at the time of detecting the amount of heat of the remaining hot water. 1 is a hot water storage tank, 2 is a heating element, 6 is a constant hot water amount setting device, 7 is a provisional hot water rate setting device, 8 is a water supply temperature sensor, 9 is a calculator A, 10 is a residual water heat amount detector, 11 is a calculator B , 12 is a timer device, 13
is a temperature detector, 17 is a circulation pump (stirring device),
18 is a communicating pipe.

Claims (1)

[Claims] 1. A constant hot water amount setting means for presetting the regular amount of hot water used to be stored in the hot water storage tank, a provisional hot water amount setting means for presetting the temporary hot water amount for one-time use, and a temperature setting of the water supplied to the hot water storage tank. a calculation means for calculating the calorific value of the amount of hot water to be stored from the set value set by the steady hot water amount setting means or temporary hot water rate setting means and the feed water temperature detected by the feed water temperature detection means; and A and
A remaining water heat amount detection means detects the remaining water heat amount by detecting a temperature change 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, and the calculation means A and the remaining water heat amount detection means detect the remaining water heat amount. a calculation means B that calculates the required energization time to the heating element from the difference in the amount of heat generated; and a calculation means B that controls the start time of energization to the heating element so that the required energization time calculated by the calculation means B is obtained at the end time of the late-night power supply. A control device for a hot water storage type electric water heater equipped with a timer device.