JP3126208B2 - Hot water storage type electric water heater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot water storage type electric water heater.

[0002]

2. Description of the Related Art An ordinary hot water storage type electric water heater uses electric power supplied only during a specific time period, such as midnight power, to heat hot water in a hot water storage tank. A simple and inexpensive energization control device for a hot water storage type electric water heater determines the boiling temperature from the water temperature detected by a water temperature sensor provided in the lower area of the hot water tank, and controls the energization of the heater based on this boiling temperature. I'm boiling hot water. However, if the boiling temperature is determined only by the actual water temperature, the water temperature sensor may not measure the actual water temperature when the amount of hot water used is small. Therefore, an energization control device that determines the boiling temperature in consideration of not only the water temperature measured by the water temperature sensor but also the previous boiling temperature such as the water temperature has been proposed (Japanese Utility Model Application Publication No.
No. -77152).

[0003]

In order to use the previous boiling conditions, the previous boiling conditions must be stored in a memory, and a backup power supply for backing up the memory must be secured. As a technique for obtaining a backup power supply, a technique of using a commercial power supply to which power is supplied for 24 hours as a backup power supply, a technique for realizing a backup power supply, and a method for obtaining a backup power supply are disclosed.
A technique has been proposed in which a power storage means charged by late-night power as shown in Japanese Patent Application Publication No. 01-2001 is used as a backup power supply. However, if a commercial power supply is used as a backup power supply, a transformer and a power supply circuit are separately required, which causes a problem that the price of the hot water storage type electric water heater is significantly increased. Further, when the storage means is used as a backup power source, a battery or a large-capacity capacitor is required as the storage means, and a charging circuit for charging the storage means is required. There is a problem of getting higher. In addition, there is a problem that a power storage unit including a battery, a capacitor, and the like has a life, a situation in which backup cannot be performed due to deterioration of performance occurs, and maintenance and replacement of the power storage unit are required.

[0004] It is an object of the present invention to provide a hot water storage type electric water heater capable of performing control in consideration of the previous boiling condition without using a specific power such as midnight power or the like as a power source and requiring a backup power source. is there.

[0005]

SUMMARY OF THE INVENTION The present invention is based on a boiling temperature obtained from a water temperature detected by a water temperature sensor provided in a lower region of a hot water tank and a previous boiling condition.
The present invention is directed to a hot-water storage type electric water heater provided with an energization control device that controls energization of a heater to boil hot water.

According to the first aspect of the present invention, as shown in the claim correspondence diagram shown in FIG. 1, a hot water temperature sensor 2 for measuring the remaining hot water temperature is provided in an upper region of the hot water tank, and is used as a power supply for the power supply control device. The power supplied only during a specific time zone is used. The energization control device includes a heating temperature determining means 3, a heating temperature back calculation means 4, a control heating temperature determination means 5,
And the power supply control means 6. The boiling temperature determining means 3 determines the boiling temperature T1 based on the water temperature t1 detected by the water temperature sensor 1. Boiling temperature back calculation means 4
Calculates the boiling temperature T2 at the end time of the previous specific time zone from the hot water temperature t2 measured by the hot water temperature sensor 2.
The control boiling temperature judging means 5 compares the boiling temperature T2 calculated by the boiling temperature reverse calculation means 4 with the boiling temperature T1 calculated by the boiling temperature determining means 3, and calculates the higher boiling temperature. Is output as the control boiling temperature T. The energization control means 6 determines the control boiling temperature T
Is controlled to energize the heater 7 to boil the hot water within a specific time zone.

According to the second aspect of the invention, as shown in the embodiment shown in FIG. 3, the power supply control means 6 controls the power supply based on the difference between the control boiling temperature T and the water temperature t1. If so, a water temperature changing means 8 is further provided.
The water temperature changing means 8 detects the water temperature t detected by the water temperature sensor 1.
When 1 is higher than the upper limit temperature tr, the detected water temperature is changed to a predetermined water temperature equal to or lower than the upper limit temperature and output to the power supply control means.

[0008]

According to the first aspect of the present invention, in order to know the previous boiling condition without using a memory or a backup power source, the boiling temperature reverse calculation means 4 is used to calculate the previous boiling temperature from the hot water temperature t2 measured by the hot water temperature sensor 2. The boiling temperature T2 at the end time of the specific time zone is calculated backward. For example, if the temperature drop rate with respect to the time of the hot water temperature in the hot water tank is known, the temperature drop during the power outage time from the end time of the specific time zone to the start time of the specific time zone can be known. By adding this drop temperature to the hot water temperature measured by the hot water temperature sensor, the previous boiling temperature can be estimated. The present invention solves the problem in the case where the boiling temperature is determined only by the water temperature using the previous boiling temperature obtained by back calculation. That is, when the amount of hot water used is small, as shown in FIG.
May measure the temperature of the boundary layer b (the temperature change layer between the layer h of the heated hot water temperature and the layer w of the water) b in the hot water tank 9. When the temperature of the boundary layer b is detected as the water temperature t1,
Since the boiling temperature T1 is determined on the assumption that the water temperature is high, it is not possible to raise the temperature to a required temperature, and insufficient boiling occurs. Therefore, in the present invention, the control boiling temperature determination means 5 compares the boiling temperature T2 calculated by the boiling temperature reverse calculation means 4 with the boiling temperature T1 calculated by the boiling temperature determination means 3 and finds that the temperature is higher. Is output as the control boiling temperature T. Therefore, even when the water temperature sensor 1 measures the temperature of the boundary layer b and the boiling temperature determining means 3 determines a low boiling temperature, the previous boiling temperature T2 obtained by the back calculation is used as the control boiling temperature T for the hot water. Boiling, so there is no shortage of boiling.

When the energization control means 6 is configured to control energization based on the temperature difference (T-t1) between the control boiling temperature T and the water temperature t1, the water temperature sensor 1 detects the boundary layer b When the temperature is detected, the temperature difference becomes too small in some cases, and the energization control error becomes larger than an allowable range, resulting in insufficient boiling. Therefore, in the invention of claim 2, when the water temperature detected by the water temperature sensor 1 is higher than a predetermined upper limit temperature tr (for example, 38 ° C.), the detected water temperature t1 is reduced to a predetermined water temperature lower than the upper limit temperature (for example, 13 ° C.).
To prevent the temperature difference from becoming smaller than the allowable range. Thus, according to the present invention, the occurrence of insufficient boiling can be prevented by setting the power supply control error within an allowable range.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 2 shows a hardware configuration of an embodiment of the hot water storage type electric water heater of the present invention, and FIG. 3 shows an example of a configuration of a power supply control device. In FIG. 2, 1 is a water temperature sensor, 2 is a hot water temperature sensor, AC is a specific power source such as a midnight power source, 9 is a hot water tank, and 10 is an energization control device.
The water temperature sensor 1 is provided in a lower region of the hot water tank 9 and measures the temperature t1 of supplied water. In this example,
Temperature that raised the boiling water temperature sensor 1 in the heater 7 is also measured. Hot water temperature sensor 2 is provided in the upper region of hot water tank 9 and measures remaining hot water temperature t2. The mounting position of the hot water temperature sensor 2 is a position at which hot water boiled in an average usage state of hot water remains. The energization control device 10 operates using only a specific power source such as a midnight power source as a power source, and does not use a commercial power source or a backup power source.

In the present embodiment, the power supply control device 10
As shown in FIG. 3, the boiling temperature determining means 3, the boiling temperature reverse calculating means 4, and the controlling boiling temperature determining means 5
And a power control means 6 and a water temperature changing means 8. The boiling temperature determining means 3 comprises a boiling temperature selecting means 31 and a boiling temperature selecting table 32, and determines a boiling temperature T1 based on the water temperature t1 detected by the water temperature sensor 1. Boiling temperature selection means 31
Is activated when the supply of the specific electric power is started, reads out the boiling temperature T1 from the boiling temperature selection table 32 based on the water temperature t1 detected by the water temperature sensor 1, and outputs it to the control boiling temperature determination means 5. I do. An appropriate boiling temperature T1 is stored in advance in the temperature selection table 32 corresponding to a water temperature range of, for example, 0 ° C. to 38 ° C. The boiling temperature T1 is determined with reference to test data and the like.

The boiling temperature back calculation means 4 is composed of a boiling temperature calculating means 41 and a coefficient setting means 42. The boiling temperature at the end time of the last specified time zone is determined from the hot water temperature t2 measured by the hot water temperature sensor 2. Back-calculate T2. Boiling temperature calculation means 41, when the energization of the specific power is started,
Temperature drop rate α [° C /
hr] and the power outage time (16 hours) from the end time of the specific time zone (for example, 7:00 am) to the start time of the specific time zone (for example, 11 hours), a temperature drop (α × 16) is calculated. By adding the falling temperature to the hot water temperature t2 measured by the hot water temperature sensor 2, the previous boiling temperature T2 = t2 +
(Α × 16) is calculated. The coefficient setting means 42 sets the temperature drop rate α as a coefficient, for example, sets the temperature drop rate α in a predetermined range centered at 0.5 [° C./hr]. Although it varies depending on the area, the guideline of the temperature drop rate α in a relatively warm area is 0.4 from spring to autumn.
０．６0.6 [° C./hr], and 0.6 to 0.7 in winter.
The coefficient setting means 42 may be configured to be set as a constant at the time of shipment from the factory, or may be configured to be able to automatically adjust as appropriate.

The control boiling temperature judging means 5 compares the boiling temperature T2 calculated by the boiling temperature reverse calculating means 4 with the boiling temperature T1 calculated by the boiling temperature determining means 3 to determine which temperature is higher. The boiling temperature is output as a control boiling temperature T. In the hot water storage type water heater, the shortage of hot water, that is, the shortage of boiling water is the most serious problem. If the higher boiling temperature is used as the control boiling temperature T, it is possible to prevent a significant shortage of boiling. The energization control means 6 of this embodiment calculates the energization time H to the heater from the temperature difference (T-t1) between the control boiling temperature T and the water temperature t1 and a constant to energize the heater 7. Control. Specifically, the power supply control means 6 includes a power supply time calculation means 61, a timer 62, a power supply circuit 63 and a boiling determination means 64. The energization time calculating means 61 multiplies the aforementioned temperature difference (T-t1) by a constant K and energization time H = (T-t1).
1) Calculate × K. Here, the constant K is previously determined from the capacity of the hot water tank and the amount of heat generated by the heater. If the capacity of the hot water tank is 370 liters and the amount of heat generated by the heater is 4.4 KW, K is 6. It becomes 5.
When the water temperature sensor 1 detects the temperature of the boundary layer b as the water temperature t1, the temperature difference (T-t
1) may be too small and the energizing time H may be too short. Therefore, in this embodiment, the inconvenience of this point is solved by using the water temperature changing means 8. When the water temperature t1 measured by the water temperature sensor 1 becomes higher than an allowable upper limit temperature (for example, 38 ° C.), the water temperature changing means 8 does not output the measured water temperature t1 to the power-on time calculating means 61 as it is, but sets the water temperature t1 as the upper limit. A predetermined temperature lower than the temperature (for example, 13
° C) and outputs it to the energization time calculation means 61. As a result, the temperature difference increases, and the occurrence of insufficient boiling can be reliably prevented. The change temperature is appropriately determined in consideration of the maximum boiling temperature, the tank capacity, etc. However, if the change temperature is set to 1/2 to 1/3 of the upper limit temperature, good results can be obtained in most cases. I know. Timer 62
Is the energizing time H calculated by the energizing time calculating means 61
Is set so as to end at the end time of the specific power, and the power supply circuit 63 supplies power to the heater 7 in the power supply time period set by the timer 62. The boiling determination means 64 determines whether the boiling water temperature detected by the water temperature sensor 1 reaches the control boiling temperature T, and detects that the boiling water temperature has reached the control boiling temperature T. Then, an energization stop command is output to the energization circuit 63. When the energization circuit 63 receives the energization stop command, the energization circuit 63 stops energization to the heater 7 even before the end time of the energization of the specific power.

Of the components of the embodiment shown in FIG. 3, the boiling temperature determining means 3, the boiling temperature back calculation means, the main part of the power supply control means 6, and the water temperature changing means 8 can be constituted by using a computer. it can. FIG. 4 shows an example of a flowchart showing an algorithm of a program for operating the computer in that case. FIG. 5 shows step ST9 of FIG.
It is a flowchart of a subroutine. 4 and 5
In steps ST2 and ST3, the boiling temperature determining means 3 is realized, steps ST4 and ST5 realize the boiling temperature reverse calculating means, and steps ST6 to ST8 realize the controlling boiling temperature determining means 5, and in step ST92. to 94 can be regarded as the water temperature changing means 8, step ST 96 is realized energization time calculation means, steps ST10 and 11 timer 6
2 are realized, and steps ST12 and ST13 realize the boiling determination means 64.

In the above embodiment, the boiling temperature determining means 3 is composed of the boiling temperature selecting means 31 and the boiling temperature selecting table 32. However, the structure of the boiling temperature determining means 3 is not limited thereto. Not limited
For example, the boiling temperature determining means 3 may be configured so that the boiling temperature T1 is calculated by using an arithmetic expression having at least the water temperature t1 as a variable. Further, the configuration of the power supply control means 6 is not limited to the above embodiment.

[0016]

According to the first aspect of the present invention, even if the previous boiling condition is not stored in the memory held by the backup power supply, the control boiling temperature determination means can calculate the boiling temperature back calculation means. The water temperature sensor compares the temperature of the boundary layer with the higher boiling temperature as the control boiling temperature by comparing the boiling temperature calculated by the back calculation with the boiling temperature determined by the boiling temperature determining means. Measure
Te, even when the boiling temperature determination means has determined a low boiling temperature, can be increased boiling hot water as the temperature boiling control the last boiling temperature obtained by back calculation, the occurrence of shortage can be prevented boiling There are advantages.

According to the second aspect of the present invention, when the power supply control means is configured to control the power supply based on the temperature difference between the control boiling temperature and the water temperature, the measured water temperature is insufficiently heated. Since the measured water temperature is changed to a predetermined low water temperature that is equal to or lower than the upper limit temperature when the temperature becomes higher than the upper limit temperature, the temperature difference is prevented from becoming too small, and the occurrence of insufficient boiling can be reliably prevented. There are advantages.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims of the invention of claim 1;

FIG. 2 is a view for explaining a schematic configuration of the entire hot water storage type electric water heater of the present invention.

FIG. 3 is a block diagram of a main part of one embodiment of the present invention.

FIG. 4 is a flowchart showing an algorithm of a program used when a main part of the embodiment of FIG. 3 is realized using a computer.

FIG. 5 is a flowchart of a subroutine of step ST9 in FIG. 4;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Water temperature sensor, 2 ... Hot water temperature sensor, 3 ... Boiling temperature determination means, 4 ... Boiling temperature back calculation means, 5 ... Controlling boiling temperature determination means, 6 ... Electricity control means, 7 ... Heater,
8: Water temperature changing means, 9: Hot water tank, 10: Electricity control device.

Claims (2)

(57) [Claims] 1. An energization control device for controlling energization of a heater based on a boiling temperature obtained from a water temperature detected by a water temperature sensor provided in a lower region of a hot water tank and a previous boiling condition to boil hot water. A hot water storage type electric water heater comprising: a hot water temperature sensor for measuring a remaining hot water temperature in an upper region of the hot water tank, using power supplied only during a specific time period as a power supply of the energization control device; A heating temperature determining means for determining a heating temperature based on the water temperature detected by the water temperature sensor; and a heating temperature at the end time of a previous specific time zone from the water temperature measured by the water temperature sensor. Boiling temperature back calculation means for back calculation, and comparing the boiling temperature calculated by the boiling temperature back calculation means with the boiling temperature determined by the boiling temperature determination means, the temperature is calculated. A control boiling temperature determining means for outputting a higher boiling temperature as a control boiling temperature, and controlling energization of the heater based on the control boiling temperature to supply hot water within the specific time zone. A hot-water storage type electric water heater characterized by comprising a heating control means for boiling. 2. The method according to claim 1, wherein the power supply control means controls power supply based on a difference between the control boiling temperature and a water temperature. When a water temperature detected by the water temperature sensor is higher than an upper limit temperature, 2. The hot water storage type electric water heater according to claim 1, further comprising a water temperature changing unit that changes the detected water temperature to a predetermined water temperature equal to or lower than the upper limit temperature and outputs the detected water temperature to the energization control unit.