JP2858788B2 - Operation control method of electric water heater - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a control method for calculating an energization time zone required by an electric water heater.

[Conventional technology]

As described in JP-B-63-35904, the conventional apparatus calculates the amount of remaining hot water in a tank, and calculates the required power supply time and the number of power supply time zones based on the remaining hot water amount.

[Problems to be solved by the invention]

In the above prior art, no consideration is given to the calculation accuracy, the difficulty of the calculation, and the commonality of the calculation in the calculation of the energization time, and it is difficult to handle with an inexpensive microcomputer (4-bit microcomputer).

An object of the present invention is to provide a calculation method which simplifies calculation contents and can be easily handled by a 4-bit microcomputer without lowering the calculation accuracy.

[Means for solving the problem]

In order to achieve the above object, the operation control method of the electric water heater of the present invention divides a power supply time period into small time periods,
In the method for controlling the operation of the electric water heater, the necessary energizing time for retaining the required heat quantity is calculated, and the necessary energizing time is allocated according to a predetermined priority order in the above-mentioned small time zone, from the target boiling temperature (T _o ). , By multiplying a constant number (C) by a value obtained by subtracting the temperature sensor (T _m ) obtained by Equation (A) or Equation (B) from the temperature sensor attached over the entire length of the tank in the vertical direction. It is characterized in that the number of required power supply time zones (N) is calculated.

_{T m = f · T 1 +} (1-f) · T 2 ··· (A) T m = f 1 · T 1 + f 2 · T 2 + ··· + f n · T n ··· (B) Here, T ₁ : Upper temperature in tank T ₂ : Lower temperature in tank f: Ratio of remaining hot water in tank to tank capacity T ₁ , T ₂ , ..., T _n : Temperature in tank f ₁ , f ₂ ,..., F _n : Capacity ratio f ₁ + f ₂ +... + F _n = 1 corresponding to the temperature in each tank.

In this case, when the power supply time period ends, if the target boiling temperature (T _o ) has not been reached, the difference between the target boiling temperature (T _o ) and the actual temperature is a constant (C).
Can be added to the number of required power supply time zones (N) in the next calculation.

As described above, the operation control method of the electric water heater according to the present invention includes:
Numerical values to be handled are standardized to maintain the calculation accuracy and simplify the calculation.

Further, the arithmetic expression is modified so that the control device itself can be shared even if the tank capacity of the water heater changes.

[Action]

Generally, the required energization time T _B of an electric water heater is Is represented by Here, Q _o is the amount of heat should be貯Wae (Kc
al), Q _T is the amount of heat retained in the tank (Kcal), P is the heater capacity (kW), and η is the heating efficiency.

The amount of heat Q _O to be stored is represented by Q _O = T _O × V _T (Kcal) (2). Here T _O is the boiling target temperature, V _T is the tank capacity of the water heater.

The amount of heat Q _T held in the tank generally includes the amount of heat of the remaining hot water and the amount of heat of the supplied water.

In the conventional control device, a plurality of temperature sensors are provided in the vertical direction of the tank, and the amount of remaining hot water in the tank is calculated by detecting the temperature of each part. _{expression, Q T = T h × V} h + T w × (V T -V h) ...... (3) here Th: the temperature of the remaining hot water, Vh: the remaining hot water, Tw: a tank bottom temperature.

The number N of times of energization is represented by N = T _B / ΔT (4), where ΔT is the width of the divided small time zone.

However, focusing on the average temperature in the tank, (3)
The equation can be transformed into Q _T = T _m × V _T (5). Here, _Tm is the average temperature in the tank.

Summarizing equation (5) and equations (1) and (2), Equation (4) is Can be expressed as

V _T , △ T, P, η is a unique value for the water heater and has a constant value. Therefore, equation (7) is simplified as N = C · (T _o −T _m ) (7) ′ Can be

The present invention focuses on the average temperature in the tank, by treating the detected tank representative temperature as the average temperature T _m in the tank, it is to simplify the calculation.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a schematic structural view of one embodiment of the present invention. A water supply pipe 2 is provided below the tank 1, and a tapping pipe 3 is provided above the tank 1. The water in the tank 1 is heated by the heater 4. Reference numeral 5 denotes a temperature sensor mounted over the entire length of the outer surface of the tank 1 in the vertical direction, and detects an average representative temperature of the tank 1 in the vertical direction. Reference numeral 6 denotes a control device which controls ON / OFF of the heater 4 based on a signal of the temperature sensor 5 and the like.

FIG. 2 is a flowchart of the control method of the above embodiment. First, the temperature detected by the temperature sensor 5 is set as the tank internal representative temperature Tm. Next, based on the representative temperature Tm, the necessary number N of energization time zones is calculated.

N is calculated by the following equation: N = C · (To−Tm). Here, To is a preset target boiling temperature.

 C is a constant calculated in advance by the following equation.

Next, the number N of the necessary energization time zones that are found out above is allocated to the power energization time in accordance with a predetermined priority, and an energization pattern is created. According to this energization pattern, ON / OFF of energization to the heater 4 is controlled by a built-in timer.

According to such a configuration, the operation formula is simple, the software can be simplified, and the memory of the operation unit can be saved. Furthermore, since only variables relating to temperature are handled at the time of calculation, there is an effect that the calculator can be shared if the ratio of the tank capacity to the heater capacity is constant.

In the above embodiment, the temperature sensor 5 detects the average temperature in the tank.
The representative temperature Tm may be calculated by detecting the ratio of the amount of remaining hot water in the tank to the tank capacity, and weighing and averaging the respective temperatures with the ratio.

FIG. 3 is a schematic structural diagram of the above embodiment, and FIG. 4 is a block diagram of a calculator for the representative temperature Tm.

The upper temperature T ₁ is detected by the temperature sensor 8 attached to the upper part of the tank.
Detecting a lower temperature T ₂ by the temperature sensor 9 attached to the tank bottom a. 7a to 7c are temperature sensors distributed in the vertical direction of the tank, and detect a ratio f of the amount of remaining hot water in the tank to the tank capacity. This is the position where each temperature sensor corresponds to the ratio of the tank capacity, for example, 1/4, 1/2,
It can be realized by mounting at 3/4 position.

Based on the above detected values T ₁ , T ₂ and f, the representative temperature Tm
Is calculated.

_{Tm = f · T 1 + (} 1-f) · T 2 following control flow is the same as in Figure 2.

Also, if you consider the heat energy of the remaining hot water as extra,
It is also possible to use the tank bottom temperature T ₂ as the representative temperature. In this case, the lower temperature T ₂ is the target boiling temperature
By turning off the heater when the temperature reaches T ₀ , overheating can be prevented.

When the temperature in the tank is distributed in multiple layers, the temperature at several points on the tank may be detected, and the representative temperature Tm may be calculated by weighted averaging the detected values.

For example, as shown in the schematic configuration diagram of FIG. 5, temperature sensors 10a to 10e are arranged in the vertical direction of the tank as shown in the embodiment, and each detected temperature t ₁ to t is represented by each temperature sensor. Tm may be calculated by performing weighted averaging with the following formula using the capacity ratios f _{1 to} f ₅ .

Tm = a _{f 1 · t 1 + f 2} · t 2 + f 3 · t 3 + f 4 · t 4 + f 5 · t 5 here _{f 1 + f 2 + f 3} + f 4 = 1.

FIG. 6 is a flowchart of another embodiment of the present invention.

At the same time that the midnight power starts, the representative temperature in the tank is detected by the above method. Subsequently, the number of energization time zones is calculated. In this calculation, the correction term α is added to a numerical value calculated from the target boiling temperature and the representative temperature in the tank.
Usually, the value of α is 0.

Next, the calculated energization time zone number is allocated to a small time zone obtained by subdividing the power supply time zone, and an energization pattern is created.

The above processing is repeated until the first heater ON occurs.

According to such a configuration, when the user uses hot water after the start of power supply at midnight and the amount of remaining hot water in the tank decreases,
Since the energization pattern is immediately corrected, it is possible to minimize insufficient boiling.

Next, after the energization of the heater is started, ON / OFF of the heater is controlled according to the created energization pattern until the end of midnight power. When the end time of the midnight power is reached and the boiling temperature has not reached the target temperature, a value obtained by adding a certain number to the difference is added to the conventional correction term α, and this is newly set as the compensation term α. Note that the constant number is the same value as the constant number used when calculating the number of energization time zones. The calculated correction term is used when calculating the number of energization time zones on the next day.

According to such a configuration, a constant voltage shortage, or
Insufficient boiling can be prevented from occurring due to the use of hot water during the midnight power supply.

〔The invention's effect〕

According to the present invention, the number of required power supply time periods is calculated by multiplying a value obtained by subtracting the average temperature in the tank from the target boiling temperature by a constant number, thereby simplifying the calculation and the memory contents, and improving the calculation accuracy. Can be easily calculated by an inexpensive microcomputer or the like without dropping the data.

If the target boiling temperature has not been reached at the end of the power supply time period, a value obtained by multiplying the difference between the target boiling temperature and the actual temperature by a constant constant is a necessary energizing time period for the next calculation. By adding to the number, it is possible to prevent shortage of heating due to shortage of supply power and use of hot water constantly generated during energization of the heater.

[Brief description of the drawings]

FIG. 1 is a schematic structural diagram of one embodiment of the present invention, and FIG. 2 is a control flowchart in FIG. 3 and 5 are schematic structural views of another embodiment of the present invention, and FIG. 4 is a block diagram of an arithmetic circuit of the embodiment of FIG. FIG. 6 is a flowchart of still another embodiment. 1 ... tank, 5 ... temperature sensor, 7a, 7b, 7c, 8, 9, 10a ~
10e …… Temperature sensor.

Continuation of the front page (56) References JP-A-57-169532 (JP, A) JP-A-61-8553 (JP, A) JP-A-60-207851 (JP, A) JP-A-61-11552 (JP) , A) JP-B-63-35904 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) F24H 1/18 302

Claims (4)

(57) [Claims] 1. The power supply time zone is divided into small time zones,
In the method for controlling the operation of the electric water heater, the necessary energizing time for retaining the required heat quantity is calculated, and the necessary energizing time is allocated according to a predetermined priority order in the above-mentioned small time zone, from the target boiling temperature (T _o ). The required number of energizing time zones (N) is calculated by multiplying a value obtained by subtracting the average temperature in the tank (T _m ) obtained by the temperature sensor attached over the entire length in the vertical direction of the tank by a constant number (C). An operation control method for an electric water heater. 2. The power supply time zone is divided into small time zones,
In the method for controlling the operation of the electric water heater, the necessary energizing time for retaining the required heat quantity is calculated, and the necessary energizing time is allocated according to a predetermined priority order in the above-mentioned small time zone, from the target boiling temperature (T _o ). An electric water heater characterized in that a required number of energizing time zones (N) is calculated by multiplying a value obtained by subtracting the average tank temperature (T _m ) obtained by the equation (A) by a constant number (C). Operation control method. T _m = f · T ₁ + (1−f) · T ₂ (A) where T ₁ : upper temperature in the tank T ₂ : lower temperature in the tank f: amount of remaining hot water in the tank with respect to the tank capacity Ratio. 3. The power supply time period is divided into small time periods,
In the method for controlling the operation of the electric water heater, the necessary energizing time for retaining the required heat quantity is calculated, and the necessary energizing time is allocated according to a predetermined priority order in the above-mentioned small time zone, from the target boiling temperature (T _o ). An electric water heater characterized in that a required number of energizing time zones (N) is calculated by multiplying a value obtained by subtracting the average tank temperature (T _m ) obtained by the equation (B) by a constant number (C). Operation control method. T _m = f ₁ · T ₁ + f ₂ · T ₂ + ... + f _n · T _n ... (B) where T ₁ , T ₂ , ..., T _n : tank temperature f ₁ , f ₂ ,..., f _n : Capacity ratio f ₁ + f ₂ +... + f _n = 1 corresponding to the temperature in each tank. 4. When the power supply time period ends, if the target boiling temperature (T _o ) has not been reached, the difference between the target boiling temperature (T _o ) and the actual temperature is a constant (C). 4. The operation control method for an electric water heater according to claim 1, wherein a value obtained by multiplying by (N) is added to the number of required power supply time zones (N) in the next calculation.