JPH0328656B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention provides a system for incorporating CO sensors and other incomplete combustion detection elements into gas water heaters and other combustors to take safety measures against incomplete combustion. Regarding safety devices for combustors.

(Prior Art) The applicant of the present application first proposed an electromagnetic safety valve interposed in a fuel supply path to a burner, a drive circuit for the electromagnetic safety valve that connects an operating solenoid of the electromagnetic safety valve to a thermoelectric element, and a power source. An incomplete combustion detection circuit is connected to a relay via a control switch that opens when a gas concentration higher than a set value is detected by a CO sensor or other incomplete combustion detection element, and the normally open contact of the relay is connected to the Interventionally connected to the drive circuit, for example, when the CO concentration in the combustion exhaust exceeds a set value, the control switch opens, the relay is de-energized, its normally open contact opens, and the electromagnetic safety valve closes. The authors proposed a system in which the combustion of the burner is stopped.

(Problem to be Solved by the Invention) According to the above device, the relay is always energized during normal combustion of the burner when the CO concentration is less than the set value, and power is consumed. For example, if you use a dry battery, it will wear out quickly,
This is undesirable as it requires relatively complicated replacement.

(Means for Solving the Problems) The present invention substantially eliminates power consumption during normal combustion of the burner, thereby making it possible to fully put the incomplete combustion detection circuit into practical use as a power source using dry batteries. The present invention provides a device that prevents the incomplete combustion detection circuit from malfunctioning due to abnormal pulse-like occurrence of incomplete combustion gas when the burner is turned on or extinguished, and which is installed in the fuel supply path to the burner. a drive circuit for the electromagnetic safety valve that connects an operating solenoid of the electromagnetic safety valve to a thermoelectric element;
An incomplete combustion detection circuit connects the power supply to a relay via a control switch that opens when a gas concentration higher than a set value is detected by a CO sensor or other incomplete combustion detection element, and the relay is normally open. In a device in which a contact is connected to the drive circuit, the power source is composed of a dry battery, and the excitation coil of the relay has an extremely low resistance value and is used only when the normally open contact is switched from open to close and from close to open. The present invention is characterized in that the excitation coil is constituted by a special relay that is energized and that a capacitor is connected in parallel to the special relay.

(Example) Next, the present invention will be explained based on the illustrated example.

In FIG. 1, reference numeral 1 indicates an electromagnetic safety valve interposed in a gas supply path 3 that supplies fuel to the burner 2, 4 indicates a thermocouple as a thermoelectric element facing the burner 2, and an operating solenoid 1a of the safety valve 1. A drive circuit 6 for the safety valve 1 was constructed by connecting the thermocouple 4 through a normally open contact 5a of a special relay 5.

The special relay 5 has been developed recently, and its block diagram is shown in Figure 2.The V terminal is connected to the power supply, the G terminal is connected to the ground, and the V
When a voltage with a predetermined voltage increase rate as shown in Figure 3a is applied to the terminal, this is detected by the voltage detection circuit, the set switch circuit is activated, and a charging current flows to the internal capacitor as shown in Figure 3c. This current interrupts the relay coil and the third contact
As shown in Figure b, it switches to the normally open side.

In this special relay 5, when the internal capacitor is sufficiently charged, the current becomes only a very small amount of leakage current, but the contacts are held in the same state by the internal permanent magnet. Therefore, power consumption in this state can be reduced.

Furthermore, when the voltage input to the V terminal of the special relay 5 becomes lower than a predetermined voltage, the voltage detection circuit detects this, the reset switch circuit is activated, the internal capacitor is discharged, and this discharge current is activated. Then, a current flows in the opposite direction to the relay coil, returning the contact to the normally open side.

In addition, the special relay 5 and a dry battery 7 serving as its power source are also included.
are connected via two series-connected transistors 8, 8, which are control switches, and a CO sensor 9, which is an incomplete combustion detection element, and a capacitor 10 is connected in parallel to the special relay 5 to detect incomplete combustion. A circuit 11 was constructed.

In the figure, 12, 13, and 14 indicate resistors for current adjustment.

(Function) Next, to explain its operation, when the burner 2 is normally fueled and the CO concentration is at a normal value less than the set value, the CO sensor 9 is maintained at a high resistance value.
The two transistors 8, 8 are both turned on, and the set voltage from the dry battery 7 is applied to the special relay 5, and only at the beginning of the application, the special relay 5 is energized, and its normally open contact 5a is closed. Since the thermocouple 4 is heated by the burner 2 and generates a predetermined electromotive force, the electromagnetic safety valve 1 is connected to the operating solenoid 1a.
A current sufficient to keep the valve open can be passed, and the burner 2 continues to be supplied with fuel. During normal combustion in the burner 2, current flows through the incomplete combustion detection circuit 11 only when a predetermined voltage from the dry battery 7 is applied to the special relay 5.
consumption is extremely low.

Additionally, when the CO concentration reaches an abnormal value higher than the set value during combustion in the burner 2, the thermocouple 4 is heated and generates a predetermined electromotive force, but the CO sensor 9
changes to a low resistance value, so both transistors 8,
8 are turned off, and the specified voltage from the dry battery 7 is no longer applied to the special relay 5, and only when the voltage is no longer applied, the special relay 5 itself is energized, its normally open contact 5a opens, and the thermocouple 4 The power supply to the operating solenoid 1a is cut off, the electromagnetic safety valve 1 is closed, and combustion of the burner 2 is stopped, making it safe.

Furthermore, when the burner 2 is in a combustion stopped state or a misfire state, the thermocouple 4 is not heated and the actuating solenoid 1a is not energized, so the electromagnetic safety valve 1
The valve is closed, and the fail safety of the drive circuit 6 is ensured.

Therefore, at this time, there is no gas leakage, and since almost no current flows through the special relay 5, the dry cell battery 7 is hardly consumed.

Furthermore, when burner 2 is turned on and extinguished, there is an abnormal pulse of CO, which causes transistors 8 and 8 to
8 is momentarily turned off, and the predetermined voltage from the dry cell battery 7 is no longer applied to the special relay 5. However, at this moment, the charging voltage of the capacitor 10 is applied to the special relay 5, so that the special relay 5 is normally open. Contact 5a
This prevents the charging capacitor 10 from opening, thereby preventing malfunction of the device and allowing the charging capacitor 10 to be downsized.

Incidentally, since two transistors 8 are connected in series, even if one of the transistors 8 is short-circuited, the entire device can be operated normally by the other one, and the reliability of the device is improved.

(Effects of the Invention) According to the present invention, the power source of the incomplete combustion detection circuit is configured with a dry battery, and the relay in the detection circuit is configured such that the resistance value of the excitation coil is extremely small and the normally open contact is It consists of a special relay that activates the excitation coil only when switching from open to close and from close to open, and a capacitor is connected in parallel to the special relay, so power consumption during normal burner combustion is almost eliminated. As a result, the incomplete combustion detection circuit can be put to practical use as a power source for the dry cell battery, and the incomplete combustion detection circuit can be used to prevent abnormal pulses of incomplete combustion gas when the burner is turned on and off. This is extremely advantageous as it eliminates malfunctions.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing one embodiment of the device of the present invention, FIG. 2 is a block diagram explaining the structure of a special relay, and FIG. 3 is a time chart explaining the operation of the special relay. 1... Solenoid safety valve, 1a... Operating solenoid,
2... Burner, 3... Gas supply path (fuel supply path),
4...Thermocouple (thermoelectric element), 5...Special relay,
5a...Normally open contact, 6...Drive circuit, 7...Dry battery, 8...Transistor (control switch), 9...
...CO sensor (incomplete combustion detection element), 10...capacitor, 11...incomplete combustion detection circuit.

Claims (1)

[Claims] 1. An electromagnetic safety valve interposed in the fuel supply path to the burner, a drive circuit for the electromagnetic safety valve that connects the operating solenoid of the electromagnetic safety valve to the thermoelectric element, and a power supply,
An incomplete combustion detection circuit is connected to a relay via a control switch that opens when a gas concentration higher than a set value is detected by a CO sensor or other incomplete combustion detection element, and the normally open contact of the relay is connected to the In a device that is connected to the drive circuit in an interventional manner, the power source is configured with a dry cell battery, and the excitation coil is connected to the relay only when the resistance value of the excitation coil is extremely small and the normally open contact is switched from open to close and from close to open. A safety device for a combustor, comprising a special relay that is energized, and a capacitor connected in parallel to the special relay.