JP2556350Y2 - Electric boiler - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to an electric boiler equipped with a plurality of electric heaters.

(Prior art and its problems) When a plurality of electric heaters are provided in an electric boiler, if all electric heaters are turned on and off at the same time, the ability to follow the heat demand is poor. The number of electric heaters that are energized and operated is changed. In this case, since the electric heaters are sequentially energized and operated based on the operation priority, the electric heater having the higher operation priority is always energized and operated. Occur.

(Purpose of the invention) The purpose of the invention is to have little effect on the electric equipment connected to the power supply line to the electric boiler,
The aim is to average the operation of the electric heater and prolong the overall life.

(Means for Solving the Problem) The control device, which has received a signal from the heat demand detecting device attached to the boiler body, determines the number of electric heaters to be energized and operated, and energizes and operates the electric heaters according to the operation priority. The operation priority of the electric heater is changed every time the operation of the electric boiler is started, and the electric heater is continuously energized. Even during operation, the operation time of each electric heater is averaged by changing the operation priority of the electric heater.

(Operation) If the operation priority of the electric heater is changed during operation, the current supply to the electric heater that has been energized will be stopped and the current supplied to the non-energized heater will start at the same time. It may fluctuate and make stable power supply impossible. However, if the operation priority of the electric heater is changed at the start of operation of the electric boiler in which energization to all the electric heaters is stopped, the electric heater is not energized. In this case, the current does not fluctuate, and the operation priority of the electric heater can be changed to average the operation time of the electric heater. Also, if the operation priority is changed only at the start of boiler operation, energization of a specific electric heater may occur if a long period of time elapses without stopping the energization of all electric heaters. Although the operation is concentrated, the operation priority is changed each time a certain operation time elapses, so that the energization to a specific electric heater is prevented from becoming long. If the operation priority is changed while the electric heater is energized, the current will fluctuate.However, the operation priority will be changed during energization if the electric heater has been energized continuously for a certain period of time. If the operation stops in which the power to all the electric heaters is stopped before the certain time elapses, the operation priority can be changed without energizing the electric heater, and the elapsed time can be changed. Will be reset, reducing the frequency of changing the operation priority during energization with large current fluctuations, reducing the fluctuations in current during operation, and connecting to the power supply line to the electric boiler. The effect on the electrical equipment being used is reduced.

(Embodiment) An embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, a heat demand detection device 2 is attached to the boiler 1, a signal from the heat demand detection device 2 is taken into a control device 3, and the signal value and a set value set in the control device 3 are obtained. The number of energizing operations of the electric heater is determined based on the difference, and an electric signal is transmitted to the electric heater electric control device 4 to control the energizing operation of the electric heater.

FIG. 2 is an example of a circuit diagram showing a relationship between an electric heater and a switch when nine AC electric heaters are used in the case where an AC three-phase power supply is used as a power supply.

The control device determines the number of electric heaters to be energized by a value P = K (AT-ST) obtained by multiplying a difference between a set value ST set in the control device and a measurement value AT from the heat demand detection device by a proportional constant K. decide. Three sets of electric heaters form one set and energization is performed for each set. There are four ways from the stop of boiler operation to stop all electric heaters to the case of energizing all three sets according to the value of P. There is control.

Each time the value of P fluctuates by the set width D, the electric heater is turned on.
-OFF is changed, but in order to avoid hunting of ON-OFF, when the value of P falls to -D, priority group 1
Is started, and when the measured value rises to the set value and the value of P becomes 0, the energization to the electric heater is all stopped. Similarly, when the value of P decreases to −2D, energization is also started to the electric heater group of priority group 2 to make a total of two electric currents, and when the value of P increases to −D, the electric heater of priority group 2 is increased. When energization of the group is stopped and only one group of the priority group 1 is energized, when the value of P decreases to −3D, energization of the priority group 3 is also started to energize a total of three electric heater groups, When the value of P rises to −2D, the power supply to the priority group 3 is stopped, and the power supply to the two electric heater groups of the priority groups 1 and 2 is performed.

As a specific example, an example in which the temperature is detected by the heat demand detecting device, the proportional constant is 1, the set width value is 3, and the set value is 150 degrees, and the priority is changed in the pattern of FIG. Will be described.

The electric heater group to be energized has three electric heaters
The priorities of the three sets are determined, and the operation and stop are controlled by one set of three sets. Patterns 1 to 3 are defined in the priority order group, and the priority orders are set so as to shift in order.

First, it is assumed that pattern 1 is adopted first, and only the priority group 1 in pattern 1 is energized. 15 readings
When the temperature rises to 0 degrees, P = 0, and the contacts of S11, S21, and S31 that have been energized up to that point are opened, and energization to all electric heaters is stopped. Thereafter, when the detected temperature decreases and the measured value decreases to 147 degrees, which is P = -D, the priority is changed from pattern 1 to pattern 2, and S12, S22, and S22 of the priority group 1 in pattern 2 are changed. The contact of S32 is closed and energization is started. The temperature further decreases and the measured value becomes P =-
S13 / S2 of priority group 2 when it drops to 144 degrees which is 2D
3. The contacts of S33 are closed, and a total of two sets of electric heaters are energized. When the measured value drops to 141 degrees, which is P = -3D, the contacts of S11, S21, and S31 of priority group 3 are closed, and power is supplied to a total of three sets of electric heaters. When the detected temperature is rising, the measured value P = −2D
When the temperature rises to 144 degrees, the contacts of S11, S21, and S31 in priority group 3 are opened, and only two sets of electric heaters are energized, and the temperature further rises, and the measured value is P = -D. 147
When the temperature rises, the contacts of S13, S23, and S33 of priority group 2 are opened, and only one set of electric heaters is energized. When the measured value rises to 150 degrees, where P = 0, priority is set The contacts of S12, S22 and S32 of the group 1 are also opened, and the power supply to all electric heaters is stopped.

The controller also accumulates the operation time of the boiler, and the power supply to all electric heaters is stopped until the set time has elapsed since the start of operation of the boiler whose priority order was changed. When the boiler is stopped, the elapsed time is reset, but when the elapsed time reaches the set time without stopping the boiler, the priority is changed. If the elapsed time from the start of the operation of the boiler reaches the set time when the power is supplied only to S11, S21, and S31 of the priority group 1 in the pattern 1, the operation priority is changed from the pattern 1 to the pattern 2 Then, energization to S11, S21, and S31 of the priority group 1 in pattern 1 is stopped, and energization to S12, S22, and S32 of the priority group 1 in pattern 2 is started.

(Effect) Since the switching of the electric heater accompanying a large current fluctuation is reduced during the operation, the fluctuation of the current during the operation is reduced, and the electric equipment connected to the power supply line to the electric boiler is affected. Has decreased. In addition, when heating is continued without changing the operation priority, the operation priority is changed every time a certain operation time elapses. Since the lengthening of the electric heaters was prevented and the operating time of each electric heater was averaged, the life of the electric heater was extended as a whole, and the replacement interval could be extended.

[Brief description of the drawings]

FIG. 1 is a schematic diagram including an electric heater electric control device and a control device of a boiler according to one embodiment of the present invention, and FIG. 2 is an electric connection diagram in a case where there are nine electric heaters according to one embodiment of the present invention. FIG. 3 shows an example of the process of detecting the number of energized sets from the measured values in one embodiment of the present invention, FIG. 4 shows an example of priority groups and patterns of electric heaters, and FIG. 5 shows another example of FIG. This is an example. DESCRIPTION OF SYMBOLS 1 ... Boiler main body 2 ... Heat demand detection device 3 ... Control device 4 ... Electric heater electric control device

Claims (1)

(57) [Scope of request for utility model registration] 1. A heating unit comprising a plurality of electric heaters, a heat demand detecting device for detecting a temperature or a pressure of a boiler for detecting a need for heating, and a control device for controlling an energizing operation of the electric heater. The control device determines the number of electric heaters to be heated by comparing the detected value of the temperature or pressure from the heat request detection device with a preset value, and determines the number of heating heaters in order of higher operation priority. In the electric boiler that energizes the electric heater of
The controller changes the operation priority of the electric heater each time the operation of the electric boiler is started, and the energization of the electric heater is continuously performed, and the operation priority of the electric heater is not changed An electric boiler provided with a control device for changing the operation priority of the electric heater even when the electric boiler is operated for a certain period of time.