JPS6148054B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device that sets the temperature of hot water in a hot water boiler or the like to a desired value and has a corrosion protection function for hot water storage and hot water supply equipment.

Hot water boilers are equipped with means to control hot water temperature, and with the rapid spread of hot water boilers in recent years, corrosion of hot water storage and hot water supply equipment has become a problem.
A method is being used to prevent corrosion by flowing a current in the opposite direction to the corrosive ion current.

The present invention provides a control device with a simple configuration that reliably performs the above two functions.

The present invention will be explained below with reference to figures showing embodiments thereof.

In the figure, 1 and 2 are DC power input terminals, and terminal 1 is a positive potential input terminal. terminals 1 and 2
The following circuits are connected in parallel between them. (1) A series circuit consisting of a resistor 3, a temperature setting device 4, and a thermistor 5. (2) Series circuit consisting of resistors 6, 7 and 8. (3) A series circuit consisting of a resistor 9, a corrosion-resistant electrode 10 set in water, a pseudo-resistor 11 made of water, and a ground electrode 12 facing the electrode 10.

(4) A series circuit consisting of a pnp transistor 13, a resistor 14, a diode 15, and a resistor 16. (Five)
A series circuit consisting of resistors 17 and 18 and an npn transistor 19. (6) A series circuit consisting of a pnp transistor 20 and a burner control circuit 21. In addition to the above circuit, this device also includes two voltage comparators 22 having two input terminals and one output terminal.
and 23 are connected, and the comparator 22
and 23 are connected to the connection point between the temperature regulator 4 and thermistor 5, and the other input terminal 22b of the comparator 22 is connected to the connection point between the resistors 6 and 7.
The other input terminal 23a of the comparators 22 and 23 is connected to the connection point between the resistors 7 and 8, and the output terminals 22c and 23c of the comparators 22 and 23 are respectively connected to the resistor 14.
and the connection point of the diode 15. Further, the connection point between the resistor 14 and the diode 15 is connected to the corrosion-resistant electrode 10 via the diode 24, and the corrosion-resistant electrode 10 is connected to the corrosion-resistant electrode 10 through the resistor 25.
A resistor 2 is connected to the base of the transistor 13 and between the base and emitter of the transistor 13.
6 is connected. Furthermore, the diode 1
The connection point between 5 and the resistor 16 is the transistor 19
The connection point between the resistors 17 and 18 is connected to the base of the transistor 20.

Next, the operation of the control device having the above configuration will be explained.

Now, the corrosion-resistant electrode 10 and the ground electrode 12 are installed at predetermined positions, and the thermistor 5 of the hot water temperature detection sensor is installed.
However, when a voltage of, for example, DC6V is applied between terminals 1 and 2 while sufficient water is being supplied to the installed hot water storage tank, the temperature of the stored hot water is set by the setting of the temperature controller 4. If the temperature is lower than the hot water temperature, a "high" level output is output on the output lines 22C and 23C of the comparators 22 and 23, respectively. In addition, approximately 6V is applied between the corrosion-resistant electrode 10 and the ground electrode 12.
A voltage of 4 to 60 mA flows through the water pseudo-resistor 11, that is, the water resistance, depending on the temperature, and the base current of the transistor 13 flows, and the transistor 13 is turned on. By selecting the resistor 9 to have a sufficiently low resistance, the potential of the corrosion-resistant electrode 10 is higher than the base potential of the transistor 19, and the transistor 19 is turned on. Therefore, the transistor 20 is turned on and current flows through the burner control circuit 21, and the well-known burner starts to be driven and the hot water is heated. When the water temperature rises to the set value of the temperature setting device 4, the resistance value of the thermistor 5 decreases to an appropriate value, and the voltage drop across the thermistor 5 becomes lower than the voltage drop across the resistor 8. The input voltages at the input terminals 23a and 23b are inverted, the output level becomes a "low" level, the potential at the connection point between the resistor 14 and the diode 15 drops to approximately the ground level, and the transistor 19 is turned off, at the same time. Transistor 20 is also turned off. Therefore, the power supply to the burner control device 21 is cut off, and the drive of the burner is stopped.

The level of the stored hot water is controlled to be kept at the same level by a float valve etc. depending on the hot water usage condition, but as the water temperature gradually decreases due to hot water usage, the resistance value of the thermistor 5 increases again. Then, the output of the comparator 23 becomes "high" level, and the burner starts to be driven as described above.

As described above, a potential of about 6 V is applied to the corrosion-protective electrode 10 regardless of the operation of the burner control device 21, and an ionic current for corrosion protection flows between it and the ground electrode. If a water cutoff or disconnection due to corrosion of the electrode 10 occurs due to a malfunction of a float valve for controlling the hot water storage level, the result will be the same as a disconnection of the water pseudo-resistor 11, and the transistor 13 will be turned off. , transistors 19 and 20 also remain off, and no current flows through burner control circuit 21.

Conversely, if the corrosion-resistant electrode 10 is covered with sludge or the like and the resistance value of the pseudo-resistor 11 is extremely reduced, the collector current of the transistor 13 flows through the diode 24, and the base current of the transistor 19 decreases. Take some of it away.

Therefore, transistors 19 and 20 remain off, and no current flows through burner control circuit 21.

As mentioned above, this device has the following safety functions in addition to the safe operation in case of water cutoff or pseudo-water cutoff and the safe operation in case of corrosion protection function decline.

If a failure occurs for some reason, such as a disconnection of the temperature controller 4 or a short circuit of the thermistor 5, the potential of the terminal 23b of the comparator 23 is lower than the potential of the terminal 23a, so the comparator 23
The output 23c is at a "low" level, and the burner control device 21 does not operate.

If the thermistor 5 becomes disconnected for some reason, the input terminal 2 of the comparator 22
Since the potential at terminal 2a becomes higher than the potential at terminal 22b, output terminal 22c becomes a "low" level and burner control device 21 does not operate.

As detailed above, according to the present invention, a safe and reliable control device for a hot water boiler or the like can be obtained by functionally combining a hot water temperature control circuit and a corrosion-resistant power supply circuit.

[Brief explanation of the drawing]

The figure is a circuit diagram showing the configuration of a control device for a hot water boiler according to an embodiment of the present invention. In the figure, 4... Temperature setting device, 5... Thermistor, 22, 23... Comparator, 13, 19,
20...transistor, 10,12...electrode plate,
21...Burner control circuit.

Claims (1)

[Claims] 1 The DC power supply, the semiconductor device that controls the burner control circuit, and one of the inverting and non-inverting input terminals are connected to the connection point of the temperature setting device and thermistor, and the other input terminal is connected to a different set reference level. The output terminals of the two connected voltage comparators are connected to a control terminal of the semiconductor device, and the control terminal of the semiconductor device is connected to a series circuit of a diode and a corrosion-resistant electrode, and a current flowing into the corrosion-resistant electrode. A control device for a hot water boiler or the like, wherein the diodes are connected to the output terminals of a second semiconductor device to be controlled, and the diodes are connected in a direction that shunts the input of the control terminals.