JPS6034009B2 - Hot water boiler control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hot water boiler control device equipped with a hot water thermistor circuit and an overheating prevention thermistor circuit. The purpose of this is to stop the power supply to the burner control circuit at the start of operation or during combustion, in order to stop combustion in abnormal conditions as soon as possible.

First of all, regarding the hot water outlet temperature, if we look at conventional hot water boilers, we find that the overflow temperature must not exceed 100℃, and that there is a 10% difference between the operating temperature of the hot water thermistor circuit and the overheat prevention thermistor circuit. Since a temperature difference between ℃ and 20qC is required, the maximum operating temperature of the hot water thermistor circuit is around 70℃, and the maximum hot water output temperature is slightly higher than that, at 7℃, which poses the problem of low hot water output temperature. .
That is, the overheating prevention thermistor circuit is activated when the hot water thermistor circuit fails, and is configured to be a manual reset type for safety reasons. In other words, in order to prevent the safety circuit from being released and restarting operation when the power is restored, the system is configured to be a manual reset type. Therefore, if the hot water thermistor circuit is normal, it is necessary to prevent the overheating prevention thermistor circuit from operating. In the hot water boiler, even after the hot water thermistor circuit operates and combustion is stopped, the hot water temperature increases by about 10 to 2000 qo due to overshoot due to the heat capacity of the boiler can. Therefore, a temperature difference corresponding to the overshoot is required between the operating temperature of the hot water thermistor circuit and the operating temperature of the overheat prevention thermistor circuit. Also, the hot water temperature is 100oo even when the overheating prevention thermistor is activated.
Must not exceed. Therefore, the thermistor for overheating prevention should be around 80° to allow for overshoot. As mentioned above, in order to provide a temperature difference of 1000 to 20°C for overshoot between the operating temperature of the hot water thermistor circuit and the overheating prevention thermistor circuit, the maximum operating temperature of the hot water thermistor circuit is around 7000. The hot water temperature will be low. An example of a conventionally known circuit that has improved the above-mentioned drawbacks is shown in FIG.

To explain briefly, 1 is a DC power supply, and 2 is an operation switch. 3 constitutes a hot water thermistor, 4 a variable resistor for regulating hot water temperature, 5 a detection increaser circuit thereof, and 9 a transistor circuit.

6 is a thermistor for overheating prevention, 7 is a resistor, 8 is its detection increase circuit, 1 is a transistor, 11 is a keep relay, 1
Reference numeral 2 indicates the contact point thereof, and b 13 indicates a burner control circuit.

In the above configuration, the set temperature of the hot water thermistor circuit is about 2 to 3 times higher than the set temperature of the thermistor circuit for overheating prevention.
The temperature is lowered. Under normal conditions, when the set value of the hot water thermistor circuit is reached, the transistor 9 is turned off, and the output stage of the thermistor circuit for overheating prevention and the boiler control circuit 1 are turned off.
Power supply to 3 is stopped and boiler operation is stopped. Even if combustion stops, 1030~2 due to overshoot as mentioned above.
Since there is a temperature rise of 0.000°C, if we only set a margin of about 2 to 3°C, the thermistor circuit for overheating prevention should be working, but since the output circuit is cut off by transistor 9, As a result, the overheating prevention thermistor circuit does not work. Therefore, there is no need to lower the setting of the hot water thermistor circuit by the amount of overshoot as in the case described above. However, if the thermistor 3 is disconnected, the resistance does not change even if the water temperature rises, so the transistor 9 remains on, and eventually the temperature reaches the set temperature of the overheating prevention thermistor 6 and its circuit 8. , the transistor 10 is turned on, the keep relay 11 is energized, and its contact 12 is turned off, turning off the burner control circuit 13. In this way, the circuit shown in Figure 1 can improve the hot water temperature, but
On the other hand, if the hot water thermistor malfunctions, it will continue to burn until the overheating prevention thermistor circuit is activated. This means that combustion will continue even if one of the two safety devices is malfunctioning, which is a safety issue. There remains a problem in terms of According to the present invention, the operating temperature of the thermistor circuit for hot water and the operating temperature of the thermistor circuit for overheating prevention can be made close to each other without any hindrance, and the maximum hot water overflow can be increased. In addition, if the hot water thermistor is disconnected or has deteriorated, it works to stop combustion, thereby increasing safety.

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

FIG. 2 shows an electrical circuit in one embodiment of the invention.

In the figure, 1 is a DC power supply, 2 is an operation switch, and 13 is a burner control circuit. 3 is a thermistor for hot water, 4 is a variable resistor for adjusting hot water temperature, 14 is a comparison increaser circuit, 16 is a transistor, 17, 18, and 19 are resistors, which are a series circuit of the thermistor 3 for hot water, resistor 20, and resistors 19, 4. A hot water thermistor circuit is mainly composed of a bridge circuit consisting of a series circuit of , and a comparison/amplifier circuit 14 .

6 is a thermistor for overheating prevention, 15 is a comparison increase circuit, 11
is a keep IJ relay, 12 is its contact, 21 is a resistor, and a bridge circuit consisting of a series circuit of hot water thermistor 3 and resistor 20, a series circuit of overheat prevention thermistor 6, resistor 21, and transistor 16, and a comparative increase. The overheat prevention thermistor circuit is mainly composed of the middle circuit 15 and the middle circuit 15.

In the above configuration, the operation is as follows during normal operation.

When the set water temperature is not reached, the hot water thermistor 3
resistance is large and the comparison booster circuit 14 is off, so the transistor 16 is turned on and the burner control circuit 13 is energized, causing combustion. When the set water temperature is reached, a signal is output from the comparison increaser circuit 14, and the transistor 1
As a result, the transistor 16 is turned off, power supply to the burner control circuit 13 and the overheat prevention thermistor circuit is stopped, and combustion is stopped. In this way, when the hot water thermistor circuit issues a dawn stop command, the overheating prevention thermistor circuit is immediately de-energized, so the set temperature of the hot water thermistor circuit should be brought close to the overheating prevention thermistor circuit's set temperature. You can also set the maximum hot water temperature higher without any problems. Next, when the hot water thermistor 3 is disconnected, the comparison increaser circuit 15 is turned on, the keep relay 11 is energized, and its contact 12 is turned off, stopping the power supply to the burner control circuit 12 and starting combustion. Stop.

Therefore, even if the power switch 2 is turned off and then turned on again, the boiler does not start operating, and combustion in a dangerous state can be avoided. In addition, if the hot water thermistor 3 is not disconnected but its characteristics have deteriorated and its temperature characteristics are worse than that of a normal product,
By comparing the potential differences based on the resistance values of the thermistors 3 and 6, the operation is performed in the same way as when the wire is disconnected, and the operation is stopped even in the middle of combustion. The extent to which the potential difference occurs to excite the keep relay 11 is determined by the resistors 20 and 21, taking into account the variations in the thermistors 3 and 6.If the thermistor 3 for hot water is disconnected or its characteristics deteriorate in this way, the temperature difference may occur during combustion. However, since the operation is stopped, there is no risk of continuing operation when the hot water thermistor circuit is abnormal and only the overheat prevention thermistor circuit is in normal condition. Another point to note is that the operation is immediately stopped in the event of an abnormality such as disconnection of the hot water thermistor 3 or deterioration of characteristics, so the maximum agreed temperature of the hot water can be raised to the set temperature for overheating prevention. In other words, in the conventional example shown in Figure 1, it was necessary to set the maximum water temperature slightly lower than the set temperature for overheating prevention, but with the present invention, it can be set to the same temperature as the set temperature for overheating prevention. . As described above, according to the present invention, a malfunction of the hot water thermistor can be discovered either at startup or during operation, and the maximum hot water temperature setting can be adjusted to prevent overheating without operating in an unsafe condition. It is possible to raise the temperature to the set value, making it possible to improve the temperature of the hot water.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a conventional example, and FIG. 2 is a circuit diagram of a hot water boiler control device according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... DC power supply, 2... Operation switch, 3... Thermistor for hot water, 4... Variable resistor for hot water temperature adjustment, 6... Thermistor for overheating prevention, 11... Keep relay, 12...
...Keep relay contact, 13...Burner control circuit (
control circuit), 14, 15...comparison amplifier circuit, 16...
- Transistor, 17, 18, 19, 20, 21...resistance. Figure 1 Figure 2

Claims (1)

[Claims] 1. A control circuit that controls the start and stop of a hot water boiler, and a hot water thermistor that senses the temperature of hot water in the hot water boiler, and supplies power to the control circuit so that the temperature of hot water is maintained at a set value. The hot water thermistor circuit is equipped with a hot water thermistor circuit that controls on/off, and an overheat prevention thermistor circuit that has an overheat prevention thermistor that senses the hot water temperature of the hot water boiler and stops power supply to the control circuit during operation. A first switching element is provided in series with the control circuit, which turns on when the hot water temperature sensed by the hot water thermistor is lower than a set value, and turns off when it reaches the set value, and the overheating prevention thermistor circuit is connected to the overheating prevention thermistor. It has a bridge circuit in which hot water thermistors are installed on different sides, and the first switching element is provided in series with the side of the overheat prevention thermistor, and the resistance values of both thermistors in the bridge circuit are compared. A comparator circuit that operates based on the potential difference between the midpoints of the bridge circuit that occurs when the thermistor is broken or deteriorated is connected, and a second switching element that is turned off when the comparator circuit operates is connected to the control circuit. A hot water boiler control device characterized by being connected in series. 2. The hot water thermistor circuit has a hot water temperature adjusting means for adjusting the set temperature, and the maximum set temperature thereof is set to a value that is the same as or slightly lower than the set temperature when the overheating prevention thermistor circuit operates. A control device for a hot water boiler according to claim 1.