JPH0328657B2 - - 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 where 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 not preferable 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 excitation coil is configured with a special relay that is energized and is provided with a capacitor that is charged to a predetermined potential when a gas concentration higher than a set value is detected by the incomplete combustion detection element, and the control switch is connected to the capacitor. It is characterized by being configured to open at a predetermined charging potential.

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

In FIG. 1, 1 indicates an electromagnetic safety valve interposed in a gas supply path 3 which is a fuel supply path to a burner 2, and 4 indicates a thermocouple which is a thermoelectric element facing the burner 2.
The operating solenoid 1a of the safety valve 1 and the thermocouple 4 were connected via a normally open contact 5a of a special relay 5 to constitute a drive circuit 6 for the safety valve 1.

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. The relay coil is energized by this current, and the contacts are switched to the normally open side as shown in FIG. 3b.

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 used. Then, a current flows in the opposite direction to the relay coil, returning the contact to the normally closed state.

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 as a control switch, a CO sensor 9 as an incomplete combustion detection element, and a capacitor 10.
, one end of which is connected to the base of both transistors 8, 8.
It was connected to the connection point with the CO sensor 9, and the other end was connected to the connection point between the special relay 5 and the negative pole of the dry battery 7, thereby forming an incomplete combustion detection circuit 11.

In the figure, 12, 13, 14, and 15 represent resistors for current adjustment, and 16 represents a diode.

(Function) Next, to explain its operation, when the burner 2 is in normal combustion and the CO concentration is at a normal value below the set value, the CO sensor 9 is maintained at a high resistance value.
The two transistors 8, 8 are both turned on, and a predetermined voltage from the dry cell battery 7 is applied to the special relay 5. 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.
Enough current can flow to keep the valve open,
Combustion in the burner 2 continues. 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, so that the consumption of the dry battery 7 is extremely small.

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 and the capacitor 10 is charged to a predetermined potential, both transistors 8, 8 are turned off, and the predetermined voltage from the dry battery 7 is no longer applied to the special relay 5, and only at the beginning when the voltage is no longer applied. The special relay 5 is energized by itself, its normally open contact 5a is opened, the thermocouple 4 de-energizes the activation solenoid 1a, the electromagnetic safety valve 1 is closed, and the burner 2 stops burning. Be safe.

Further, 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.

Note that when the burner 2 is turned on and extinguished, an abnormal pulse of CO is generated, which causes the resistance value of the CO sensor 9 to temporarily become low. 15 is connected to the capacitor 15, and when the resistance value of the CO sensor 9 changes to a low value, the capacitor 10 is temporarily charged via the resistor 15, but this charging potential does not reach a predetermined value, and the CO sensor 9 is When the normal state returns to a high resistance value, the charge in the capacitor 10 is quickly discharged via the diode 16, so both transistors 8, 8 are kept in the on state.
The normally open contact 5a of the special relay 5 does not open, so that malfunction of the device is prevented and the charging capacitor 10 can be downsized.

Note that the charge in the capacitor 10 is discharged via the CO sensor 9 and the resistor 14 when the CO concentration returns to less than the set value.

In the illustrated example, two transistors 8 are connected in series, so that even if one of the transistors 8 is short-circuited, the other can operate the entire device normally, improving the reliability of the device.

(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 incomplete combustion detection circuit is configured such that the resistance value of the excitation coil is extremely small and the resistance value of the relay in the incomplete combustion detection circuit is extremely small. A special relay is constructed in which the excitation coil is energized only when the open contact switches from open to close and from close to open, and is charged to a predetermined potential when the incomplete combustion detection element detects a gas concentration higher than the set value. Since the control relay in the incomplete combustion detection circuit is configured to open at a predetermined charging potential of the capacitor, it is possible to almost eliminate power consumption during normal combustion of the burner, and to detect incomplete combustion. Dry batteries were put to practical use as a power source for circuits, and burner points and
This is very advantageous because the incomplete combustion detection circuit will not malfunction due to abnormal pulse-like occurrence of incomplete combustion gas during extinguishing the fire.

[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,
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 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 In a device that is connected to the drive circuit in an interventional manner, the power source is composed of a dry battery, and the excitation coil has an extremely small resistance value, and the excitation coil is connected only when the normally open contact is switched from open to close and from close to open. A capacitor is provided that is charged to a predetermined potential when a gas concentration higher than a set value is detected by the incomplete combustion detection element, and the control switch is activated to charge the capacitor in a predetermined manner. A combustor safety device characterized by being configured to open at electric potential.