JPH0243986B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a water supply temperature detection device for detecting the temperature of water supplied to a hot water storage tank in a hot water storage type electric water heater that utilizes late-night electricity.

[Prior art]

Normally, in this type of electric water heater, as shown in Figure 6, tap water is supplied into a hot water storage tank a through a water supply pipe b, and is heated to a predetermined temperature (up to about 85 degrees) by a late-night power heater d at midnight. The water is boiled up to 100%, and is supplied to various places such as washrooms and bathrooms from hot water pipe c.

The hot water supplied to each location is mixed with tap water using a mixing faucet or the like, and the temperature is adjusted to an appropriate temperature, for example, around 45 degrees, before use.

By the way, the temperature of the tap water, that is, the temperature of the water supply, is affected by the air temperature and varies depending on the season or day. The amount of hot water that can be used varies depending on the height of the water.

Therefore, the temperature of the supplied water is detected using a temperature sensor, etc., and according to the detection result, the water is controlled to be boiled to the required boiling temperature that corresponds to the amount of heat (required amount of hot water) required by the user. It is made to be.

The detection position of the water supply water temperature, that is, the installation position e of the temperature detection sensor e, is as shown in FIG.
There are cases where it is provided.

In the former case, it is necessary to separately install a temperature sensor to detect the temperature of the hot water in the hot water storage tank a, which poses problems in terms of cost and construction.

In addition, in the latter case, both the water supply temperature and the hot water temperature are detected by one temperature sensor, so there are no cost and construction problems like the former. Temperature sensor e is installed in hot water tank a, so if the hot water is used, for example, if no hot water is used for a whole day, no tap water will be supplied to hot water tank a, and therefore the temperature sensor e will indicate that it was boiled yesterday. The temperature of the hot water that has been raised and remains in the hot water storage tank a (the temperature of the hot water that has dropped slightly below the boiling temperature due to heat radiation (about 75 degrees)) is detected, and this detected temperature is taken as the water supply temperature.
The next day's boiling temperature is calculated and set, and boiling control is performed.

Then, the next day, the water is mixed with tap water (about 15°) and used, so of course there will be a shortage of hot water. That is, a problem arises in that the hot water runs out.

In addition, even in the case of electric water heaters that run on late-night power as mentioned above, a heater f for daytime power (00V) is added in order to downsize the hot water storage tank a or to prevent hot water from running out. There are some that supplement the amount of heat appropriately.

In such a structure, when heater f is energized, convection occurs in hot water tank a,
If you only capture the water supply temperature once before turning on the power in the middle of the night, the value may be higher than the true water supply temperature, making the boiling calculation inaccurate and causing hot water to run out as described above. Ta.

[Purpose of the invention]

The present invention has been made in view of such conventional problems, and has a structure in which a single temperature sensor e incorporates temperature detection means for detecting the supply water temperature and the hot water temperature in the hot water storage tank a. Even if you do not use hot water at all for a whole day, by reading out the lowest temperature for a predetermined number of days stored in the water temperature storage device, you can control the boiling temperature of an electric water heater that uses electricity late at night. An object of the present invention is to provide a water supply temperature detection device for a hot water storage type electric water heater that can detect water temperature without causing any problems.

[Structure of the invention]

As shown in FIG. 1, the configuration of the present invention is such that when the temperature of the water supplied in the hot water storage tank is detected by the temperature detection means h, the detected temperature is detected by the first comparison means i.
The lowest temperature of the day is determined by periodically reading the temperature while the late-night power heater is off. This determined minimum temperature is stored for a predetermined number of days by the storage means j. The lowest value among these stored values for a predetermined number of days is determined by the second comparing means k.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

An electric water heater equipped with a water supply temperature detection device according to the present invention is shown in FIG. 2, and the electric water heater 1 is a hot water storage type that uses late-night electricity (200V electricity).
A late-night power heater (200V heater) 3 is provided in the lower part 2a of the hot water storage tank 2, and the operation of the late-night power heater 3 is controlled based on the water supply temperature detected by the water supply temperature detection device 4.

In addition, 5 is a water supply pipe that supplies tap water into the hot water storage tank 2, and is connected to the corner part of the bottom 2b of the hot water storage tank 2, and 6 is a water supply pipe that supplies tap water into the hot water storage tank 2, and 6 is a water supply pipe that supplies tap water to the hot water storage tank 2. A hot water supply pipe that supplies water supply equipment (not shown) at various locations in the hot water storage tank 2.
It is connected to the center part of the top part 2c.

When the user uses hot water with the hot water supply device, the hot water heated by the late-night power heater 3 in the hot water storage tank 2 is supplied via the hot water pipe 6, while the reduced amount of hot water is compensated for. , tap water is supplied into the hot water storage tank 2 via a water supply pipe 5.

Therefore, in the hot water storage tank 2, a boiled hot water layer is formed in the upper part 2d and a water layer is formed in the lower part 2a, thereby forming separate layers according to temperature.

Next, the detailed structure of the feed water temperature detecting device 4 is shown in FIG. 3, and the feed water temperature detecting device 4 is composed of a temperature sensor 7, a microcomputer 8, and the like.

As shown in FIG. It is provided near the top of the heater 3 at the opening 5a of the water supply pipe 5 in the lower part of the tank 2.

The temperature sensor 7 detects the water temperature or hot water temperature near the opening 5a, and sends the detection result to the microcomputer 8 as a digital signal.

Note that as the temperature sensor 7, one with a small time constant that can immediately respond to the ambient temperature is used.

The microcomputer 8 processes the detection results, and the A/D converter 9 converts an analog quantity into a digital quantity, converting the voltage signal (analog quantity) from the temperature sensor 7 into a digital quantity. , and sent to the first comparing section 10.

The first comparison unit 10 is for determining the lowest water temperature of the day detected by the temperature sensor 7, and converts the detection result from the temperature sensor 7 into an A/D converter while the late-night power heater 3 is OFF. 9 and find its lowest value.

The storage section 11 stores the minimum temperature determined by the first comparison section 10 for a predetermined number of days, and has storage areas M1 to Mn corresponding to the predetermined number of days n.

The predetermined number of days n is the hot water (or water) in the hot water storage tank 2.
For hygiene reasons, the maximum number of days that can be used without replacement is set, for example, n=4 to 7.

The second comparison unit 12 is for determining the lowest value among the lowest temperatures for a predetermined number of days stored in the storage unit 11, and takes in each of the lowest values stored in the storage areas M1 to Mn and calculates the lowest value. .

The arithmetic processing section 13 arithmetic-processes the lowest value obtained by the second comparison section 12, and calculates the value of the late-night power heater 3.
The system controls the operating time of the hot water storage tank 2, and based on this data, the minimum value determined by the second comparing section 12 is taken as the water supply temperature, and the midnight temperature required to boil the water in the hot water storage tank 2 to the required boiling temperature is determined based on this data. The operating time of the power heater 3 is calculated and determined.

Then, energization of the late-night power heater 3 is controlled via the relay 14.

Next, the operation of the feed water temperature detection device 4 will be explained with reference to the flowcharts of FIGS. 4 and 5.

When the late-night power heater 3 is turned off, the first comparator 10 sequentially takes in the water temperature detected by the temperature sensor 7 at millisecond intervals, and calculates the lowest temperature of the day according to the procedure shown in FIG.

That is, in FIG. 4, the water temperature is taken in steps. The step determines whether this captured temperature is lower than the temperature stored in the register MINM, and if it is, the step replaces the captured temperature with the data already stored in the register MINM and writes a new one. set to register MINM.

Then return to step again. On the other hand, if the temperature taken in is not lower than the temperature in the register MINM, the process returns to the step.

On the other hand, the second comparing section 12 takes in the lowest temperature stored in the storage section 11, and determines the lowest value according to the procedure shown in FIG. That is, in FIG. 5, each storage area M1 to M1 of the storage unit 11 is
The lowest temperature stored in Mn is sequentially from M1 to M2.
, from M2 to M2, . . . from Mn-1 to Mn, and the oldest lowest temperature stored in Mn is erased.

And in the step above register MINM
The temperature is set to M1 as the lowest temperature of the day.

Next, in step, the second comparator 12 takes in the lowest temperatures stored in each of the storage areas M1 to Mn, further determines the lowest value from among the lowest temperatures, and uses the determined lowest value as the minimum temperature for the water supply. The data is sent to the arithmetic processing unit 13 as water temperature data (step).

Then, the arithmetic processing unit 13 calculates and obtains the energization time of the late-night power heater 3 based on this data.

In addition, although the above-mentioned example is a case where only the heater 3 for late-night power is provided, the heater 1 for daytime power is provided.
6 (see Figure 2) is also installed. That is, when the daytime power heater 16 is energized as necessary during the daytime,
Convection occurs within the hot water storage tank 2, and separation layers according to temperature are not formed as in the above embodiment.

Therefore, during the daytime power supply heater 16 is energized, the temperature sensor 7 detects a temperature higher than the true water supply temperature.

However, when the power heater 3 is turned off in the middle of the night, that is, during the daytime, the first comparator 10 constantly takes in the water supply temperature detected by the temperature sensor 7 in a short cycle of milliseconds, and stores the lowest value. As a result, daytime power heater 1
6 could be avoided, and a temperature close to the true water supply temperature was detected.

In addition, in the above-mentioned embodiment, as shown in Fig. 4, the lowest value of the temperature taken periodically is left in the register MINM, so even if the timing of the user's use of hot water is unknown. , this means that a temperature close to the true water supply temperature has been detected.

Furthermore, even if the user does not use the hot water in the hot water storage tank 2 all day long, the storage area M of the storage unit 11
1 to Mn store n days' worth of data (minimum temperature), and the lowest value is determined by the process shown in Figure 5. Therefore, in practice, this means that a temperature close to the true water supply temperature has been detected. there is no problem.

〔Effect of the invention〕

As detailed above, the present invention has a structure in which a temperature detection means is built into the hot water storage tank, but when the water temperature in the hot water storage tank changes from moment to moment due to the influence of the heating element, a heating element for daytime power generation is also used. In this case, even under various conditions, such as when hot water is used at irregular times or when hot water is not used for a whole day, a temperature close to the actual temperature of tap water is detected, and this temperature detection device If you use this to control the boiling of a hot water storage type electric water heater, you will never run out of hot water. Further, since there is no need to separately provide a sensor for detecting the temperature of the water supply, installation is easy without requiring the labor of installing the sensor and wiring, and the overall cost can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a water supply temperature detection device in a hot water storage type electric water heater according to the present invention, and FIGS. 2 to 5 illustrate embodiments of the present invention.
The figure is a schematic diagram showing the main parts of a hot water storage type electric water heater.
The figure is a block diagram showing the outline of the configuration of the water supply temperature detection device in the same water heater, Figure 4 is a flowchart showing the operation of the device when the heater for late-night power is turned off, and Figure 5 is when the heater for late-night power is turned on. FIG. 6 is a flowchart showing the operation of the device in FIG. 6, which corresponds to FIG. 2 of the conventional hot water storage type water heater. Explanation of symbols, h...Temperature detection means, i...First comparison means, j...Storage means, k...Second comparison means, 2...Hot water storage tank, 3...Late-night power heater, 4... Water supply water temperature detection device, 5... Water supply pipe, 5
a... Mouth part, 6... Hot water pipe.

Claims (1)

[Claims] 1. In a hot water storage electric water heater that uses late-night electricity, there is a temperature detection means for detecting the temperature of water supplied to the hot water storage tank, and the temperature detected by the temperature detection means is periodically monitored while the heating element for late-night electricity is OFF. a first comparing means for calculating the minimum temperature of a day by taking in the temperature, a storage means for storing the minimum temperature determined by the first comparing means for a predetermined number of days, and a storage means for storing the minimum temperature for a predetermined number of days stored by the storage means. A water supply water temperature detecting device for a hot water storage type electric water heater, characterized in that the device comprises a second comparing means for determining the lowest value among the lowest temperatures of the hot water storage type electric water heater.