JPH0322553B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a control device for a hot water storage type electric water heater equipped with a heating element for late-night power use and a heating element for general power use (hereinafter referred to as daytime heating element). It is something.

[Prior art]

Conventionally, there have been control devices for this type of hot water storage type electric water heater as shown in FIGS. 1 and 2. In these figures, 1 is a hot water storage tank, 2 and 3
are a water supply pipe and a hot water supply pipe connected to this hot water storage tank 1, respectively, 4 is a hot water tap provided in this hot water supply pipe 3, 5 is a heating element provided in the hot water storage tank 1 for heating, and 6 is a hot water storage tank 1. 7 is the power supply, and 8 is the time switch for late-night power, which is generally turned on for 8 hours from 11:00 p.m. to 7:00 a.m. the next morning.

In the hot water storage type electric water heater having the above configuration, when the midnight power supply start time comes, the contact point of the time switch 8 is closed and power supply to the heating element 5 is started. When the temperature of the hot water in the hot water storage tank 1 reaches 85° C., the contacts of the automatic temperature controller 6 are closed and the electricity to the heating element 5 is stopped.

In this way, an electric water heater that uses electricity late at night can reach 85 degrees Celsius every day.
It is constructed to store hot water. However, users do not just use high-temperature water at 85℃;
Mix with water and use as mixed hot water at 40-45℃.
The amount of mixed hot water obtained at this time depends on the temperature of the water supply, and the amount of mixed hot water obtained in the summer when the water supply temperature is high is 60% greater than in the winter when the water supply temperature is low. However, it is said that the amount of hot water used in a typical household is determined by the size of the bathtub and the configuration of the household.
It is considered to be almost constant throughout the year. As a result, there is a large amount of unused hot water (residual hot water) in the summer.
The heat radiation loss of this residual hot water is a major factor in reducing the efficiency of use of electric water heaters.

In addition, the hot water storage tank 1 generally has a large capacity of 370 class because the hot water can be heated using only late-night electricity, and the hot water storage capacity is determined according to the maximum hot water supply load in winter. For this reason, it requires an installation area of 90 cm square, including space for piping, and this was considered one of the obstacles to the widespread use of hot water storage type electric water heaters.

[Summary of the invention]

This invention was made in view of the above problems.
Efficiency is improved by changing the temperature of boiling water depending on the temperature of the water supply, and by using a heating element for general electricity and setting the operation time of the heating element in the latter half of the late-night power supply period. The present invention provides a control device for a hot water storage type electric water heater that can reduce the hot water storage capacity and the installation area.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 3, 1 to 4, 7, and 8 have the same configurations as those shown in FIGS. 1 and 2, so corresponding parts are given the same reference numerals and their explanations will be omitted.
Reference numerals 9 and 10 denote temperature detection means each consisting of a thermistor fixed to the wall of the hot water storage tank 1 to measure the temperature of the hot water in the tank, 9 a lower temperature sensor, and 10 an upper temperature sensor. 11 is a heating element for late-night electricity controlled by the time switch 8; 12 is a daytime heating element for general electricity that is used without being restricted by the time switch 8; each is controlled by a control unit 13. Late night switch 14, daytime switch 1
5 is provided. Reference numeral 16 denotes a remaining hot water amount detection means, which detects the amount of remaining hot water in the hot water storage tank 1 based on the temperature detected by each sensor 16a, 16b, . . . , 16e. Note that the lower temperature sensor 9 measures the temperature of water supplied from the lower part of the hot water storage tank 1 when power is started in the middle of the night, and also measures the temperature of the water during boiling after power is started to be applied to the heating elements 11 and 12. It is possible.

Next, the control unit 13 will be explained using a calculation formula. First, the required heat amount calculation means 17 calculates the amount of heat that should be stored in the hot water storage tank 1 from the preset amount of boiling water and the water supply temperature measured by the lower temperature sensor 9. If the target is TU (℃) and VU (liter), and the feed water temperature detected by the lower temperature sensor 9 is TW (℃), the required heat amount KU (Kcal) is KU = VU × (TU - TW) (Kcal) ... ( 1) It can be expressed as

The boiling temperature calculation means 18 calculates the boiling temperature TO (°C) which is the boiling target for the day from the required heat amount KU obtained by the required heat amount calculation means 17 and the water supply water temperature TW detected by the lower temperature sensor 9. Then, TO=KU/VT+TW(℃)...(2) Calculate. Here, VT is the capacity () of the hot water storage tank 1.

Reference numeral 19 denotes a remaining hot water calorific value calculation means, which calculates the residual hot water calorific value from the detected values of the residual hot water amount detecting means 16 and the upper temperature sensor 10. To explain this,
First, each remaining hot water sensor (16, 16b,..., 16e) consisting of a thermistor (or thermostat, etc.)
The remaining hot water amount is measured by the remaining hot water amount detection means 16 based on the detected temperature. Now let this measured value be VZ(). Also, from the measured values of the lower temperature sensor 9 and the upper temperature sensor 10, the lower temperature is determined as TW (℃), and the upper temperature is determined as TT (℃).
Then, the residual hot water heat value KZ (Kcal) can be calculated as KZ = VZ × (TT - TW) (Kcal) ... (3).

Furthermore, 20 is an energization time setting means that judges whether or not it is necessary to energize the heating element 12 during the day in order to obtain the amount of heat calculated by the required amount of heat calculating means 17, and also determines if it is necessary to energize the heating element 11 only in the middle of the night. The function is to set the energization time, such as when to energize the heating element 11 in the middle of the night, and when to energize the heating element 12 in the daytime.The function will be described later. This is shown in flows A, B, and C shown in FIG. 4b.

The determination as to whether or not it is necessary to energize the heating element 12 during the daytime is made by comparing the amount of heat obtained by energizing the heating element 11 late at night and the amount of heat required to satisfy the user's required amount of hot water calculated by the required amount of heat calculating means 17. Do it with
The late-night power supply heat amount is the maximum value of the heat amount that the late-night heating element 11 can supply during the 8 hours of the late-night power supply time.
KWN (Kcal) can be calculated as KWN = 8 x WN x 860 x η (Kcal). On the other hand, the required heating heat amount KI (Kcal) required to satisfy the user's heat demand can be calculated using the required heat amount calculation means 17. The calculated required heat amount KU (Kcal) and the remaining hot water heat amount KZ calculated by the remaining hot water heat amount calculation means 19
(Kcal) is calculated as KI=KU−KZ(Kcal). From these two calculated values, if KWN≧KI (4), the required amount of hot water can be covered only by energizing the late-night heating element 11, so the daytime heating element 12 is not energized. On the other hand, if KWN<KI (5), it is determined that it is necessary to energize the heating element 12 during the daytime.

In the energization time setting means 20, first, (4)
If the late-night heating element 11 shown in the formula is used to generate heat, the required energization time is calculated. Late night heating element 11
The required energization time HWN (hours) can be calculated as HWN=KI/WN×860×η (6). In order to allocate this energization time to the latter half of the late-night power supply period when the power load is low, the time switch 8 is turned on, and energization to the late-night heating element 11 is started after (8-HWN) hours, and the time switch 8 is turned on. The energization time is set so that the energization to the heating element 11 is stopped in the middle of the night when it is turned off (Flow A).

On the other hand, if it is also necessary to energize the daytime heating element 12 as shown in equation (5), it is determined whether or not it is sufficient to energize the daytime heating element 12 only during the late-night power supply time. If this alone is insufficient, energization is immediately started (Flow B). In addition, when the power supply to the heating element 12 during the daytime is sufficient during the late-night power supply time, the required energization time is calculated and the energization time is shifted to, for example, a time when the power load is low. The rated capacity of the daytime heating element 12 is WD
(KW), the daytime power supply heat amount KWD (Kcal) that can be supplied by energizing the daytime heating element 12 is calculated as KWD=8×WD×860×η(Kcal). In addition, the amount of heat that needs to be relied on from the heating element 12 during the daytime is (KI-KWN) (Kcal), and when KWD≦(KI-KWN)...(7), the amount of heat that remains during the late-night energization period is insufficient. Therefore, set the power supply to start immediately. Also, when KWD>(KI-KWN)...(8), the required energization time HWD (hours) is calculated as HWD=(KI-KWN)/WD×860×η(hours)...(9). Here, in order to control the energization of the daytime heating element 12 to be completed in accordance with the end time of the late night power supply time, the energization of the daytime heating element 12 is stopped when a period of time (8-HWD) has elapsed since the midnight power supply started. Set to start (Flow C).

Reference numeral 21 denotes a heating element control device, which controls the late-night heating element 11 at the time set by the energization time setting means 20.
Then, during the daytime, the heating element 12 is energized, and when the water temperature reaches the boiling temperature TO (° C.) calculated by the boiling temperature calculation means 18, the energization is stopped. Further, 22 is a timer, which integrates the time since the time switch 8 is turned on and late-night energization is started, and is used to set the time to start energizing the late-night heating element 11 and the daytime heating element 12.

Next, the operation of the above embodiment will be explained based on the flowcharts shown in FIGS. 4a and 4b.

First, at the midnight power supply start time (for example, 23:00), the time switch 8 is turned on (step
101). At the same time as this time switch is turned on, a timer 22 is started (not shown). Also, the lower temperature sensor 9 measures the lower temperature TW (°C) (step 102). The required heat amount calculation means 17 calculates the required heat amount KU (Kcal) from the lower temperature TW (°C) and the preset target hot water amounts VU ( ) and TU (°C) using the above equation (1) (step 103). Furthermore, the boiling temperature calculating means 18 calculates the boiling temperature using the above equation (2).
Calculate TO (°C) (step 104). Next, the remaining water heat amount is calculated by the remaining water heat amount calculating means 19. This is determined by the remaining hot water amount detection means 16.
VZ () is detected (step 105), the upper temperature TT (°C) is measured by the upper temperature sensor 10 (step 106), and the remaining water heat quantity KZ is determined by the above equation (3).
(Kcal) (step 107). Then, the energization time is set by the energization time setting means 20 (step 108). After that, as mentioned above, the fourth
One of three types of control, flows A, B, and C shown in FIG. b, is performed.

First, it is determined whether it is enough to energize only the heating element 11 in the middle of the night, and the amount of heat supplied by the late-night electricity KWN is determined.
If (Kcal) is larger than the required heating heat amount K (Kcal) (formula (4)), the daytime heating element 12 is not energized and is controlled by flow A. That is, late night heating element 1
Since the required energization time HWN (h) to 1 can be calculated by the above equation (6), the energization is controlled so that it ends at the end of the midnight power supply time. The heating element control device 21 determines whether or not time (8-HWN) has elapsed since the time switch 8 was turned on based on the timer 22 (step 109);
HWN) When the time has passed, turn on the night switch 14.
Turn it on and start energizing the late night heating element 11 (step 110). The water temperature in the hot water storage tank 1 is the boiling temperature calculated by the boiling temperature calculation means 18
When TO (°C) is reached (step 111), the power supply to the late-night heating element 11 is stopped (step 112). At the same time, time switch 8 is also turned off (step
113), the boiling cycle ends.

On the other hand, in step 108, the amount of heat supplied by late-night electricity is
Required heating heat amount K (Kcal) than KWN (Kcal)
If is larger (formula (5) above), it is determined whether it is sufficient to energize the daytime heating element 12 during the late-night power supply period. As a result, there is a shortage (mentioned above).
(7)), proceed to flow B, and midnight heating element 1
1. Set the daytime heating element 12 to be energized immediately. Therefore, the heating element control device 21 turns on the midnight switch 14 and the daytime switch 15 and starts energizing them (step 114). When eight hours of the midnight power supply time have elapsed, the time switch 8 is turned off, the midnight switch 14 is turned off, and the power supply to the midnight heating element 11 is also stopped (step 115). At this time, the water temperature has not yet reached the boiling temperature TO (°C), so the daytime heating element 12 continues to be energized. Water temperature is boiling temperature
When TO (°C) is reached (step 116), the daytime switch 15 turns off the daytime heating element 12 (step 117), ending the cycle.

Also, in the case where it is sufficient to operate the daytime heating element 12 only during the midnight power supply time in step 108 (formula (8) above)
If so, proceed to flow C. First, in the energization time setting means 20, the required energization time of the daytime heating element 12 is set.
HWD (h) is calculated using the above equation (9), and in order to end the energization at the end of the midnight power supply time, the daytime heating element 12 is timed so as to start energizing when (8-HWD) time has elapsed. On the other hand, it is set to immediately start energizing the late-night heating element 11.
In flow C, first turn on the midnight switch 14.
In the middle of the night, electricity to the heating element 11 is started (step 118). Next, monitoring is performed based on the timer 22 (step 119), and when the predetermined time is reached, the daytime heating element 1 is turned on by turning on the daytime switch 15.
2 begins to be energized (step 120). As mentioned above, when the boiling temperature reaches TO (℃) (step 121), daytime switch 15 and midnight switch 1 are activated.
4 is turned off to stop energizing both heating elements 11 and 12 (step 122). Almost at the same time, the time switch 8 is turned off (step 123), and the daily cycle ends.

〔Effect of the invention〕

As explained above, according to the control device for the hot water storage type electric water heater of the present invention, the boiling water temperature is changed depending on the temperature of the supplied water, and a heating element for general electric power is also used. Efficiency is improved because there is no need to store excess hot water during use, and the hot water storage capacity can be reduced, making it possible to reduce the installation area. Furthermore, since the operating time of the heating element is in the latter half of the late-night power supply period, it is in the off-peak period of the power load (2:00 am to 6:00 am), which has the effect of contributing to the highly efficient operation of power equipment. .

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a general hot water storage type electric water heater, FIG. 2 is an electric circuit diagram thereof, and FIG. 3 is a diagram showing the configuration of a control device for a hot water storage type electric water heater according to an embodiment of the present invention. 4 is a control flow chart thereof. 1...Hot water storage tank, 9...Lower temperature sensor, 1
0... Upper temperature sensor, 11... Heating element for late-night electricity, 12... Heating element for general electricity, 16... Remaining hot water amount detection means, 17... Required heat amount calculation means, 18...
Boiling temperature calculation means, 19...Residual water heat amount calculation means, 20...Electrification time setting means, 21...Heating element control device. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A late-night power heating element that heats the water in the hot water storage tank using late-night power, a general power heating element that heats the water using general power, and a temperature detection means that measures the temperature inside the hot water storage tank and the water supply temperature. A required heat amount calculating means for calculating the amount of heat to be stored in the hot water storage tank from the water supply temperature measured by the temperature detecting means and a predetermined amount of boiling water, and the required heat amount calculated by the required heat amount calculating means and the temperature detection. a boiling temperature calculation means for calculating a target temperature for boiling from the water supply temperature detected by the means; a remaining hot water amount detection means for detecting the amount of hot water remaining in the hot water storage tank from the previous day; a detected value of the remaining hot water amount detection means and the temperature detection. a residual water heat amount calculation means for calculating the residual water heat amount from the temperature detected value in the hot water storage tank of the means, the residual water heat amount calculated by the residual water heat amount calculation means, the required heat amount calculated by the required heat amount calculation means, and the late night; energization time setting means for determining the necessity of energizing the general power heating element based on the rated power consumption of the power heating element and the general power heating element, setting the energization time, and setting the energization time of the late night power heating element; The energization time setting means includes a heating element control device that controls to start energization at the time set by the energization time setting means and to stop energization when the temperature calculated by the boiling temperature calculation means is reached, and the energization time setting means If the boiling temperature is reached by energizing only the heating element for late-night power, or if the heating element for general power is energized during the late-night power supply period, move the energization time to the latter half of the late-night power supply period. 1. A control device for a hot water storage type electric water heater, characterized in that the control device is configured to set a hot water storage type electric water heater.