JPS6143604B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas appliance, and particularly to an oxygen deficiency safety mechanism thereof, and its purpose is to improve the user's ease of use by ensuring its operation, and to The goal is to further improve safety.

This kind of gas appliances that have been used in the past, such as stoves with oxygen deficiency safety devices, use a thermocouple as a sensor to detect the lift-up of the combustion flame due to a decrease in oxygen in the room where the stove is placed, and supply the information to the stove. I'm trying to turn off the gas. In other words, under normal conditions, the conventional method heats the thermocouple with combustion flame, and uses the thermoelectromotive force to excite the solenoid valve installed in the gas circuit, thereby keeping the gas circuit open and supplying gas. In addition, in the event of oxygen deficiency, the electromagnetic valve is closed as the thermoelectromotive force decreases due to the lift-up of the combustion flame, thereby automatically stopping the gas supply.

However, with this configuration, the thermoelectromotive force of the thermocouple decreases due to temporary fluctuations in gas pressure or fluctuations in the combustion flame due to the opening and closing of the door, which often causes the gas circuit to be cut off at the same time as oxygen deficiency occurs. However, the ignition operation had to be performed each time, which was extremely inconvenient. Another problem is that at the beginning of use, it is inconvenient to manually hold the solenoid valve open until the thermocouple is sufficiently heated.

Therefore, in the present invention, a control circuit is provided to at least stop the gas supply to the main burner when the combustion flame continues to change for a predetermined period of time or more, and a flame swing timer and a combustion start timer are used in common. This is an attempt to eliminate the above-mentioned conventional drawbacks.

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

The upper part of Figure 1 shows the control circuit, and the lower part shows the gas circuit. 1 is the main burner, 2 is the oxygen deficiency detection burner that also serves as a pilot burner, and a thermocouple 3 is fixed in the center as a sensor. . 4 and 5 are the combustion flames of the oxygen deficiency detection burner 2, 5 is the combustion flame during normal operation, and 4 is the combustion flame during oxygen deficiency. In this case, thermoelectromotive force is generated for the thermocouple 3 on the order of several tens of millivolts during normal conditions and several millivolts during oxygen deficiency. This relationship will be explained using FIG. 2. In this Figure 2, A indicates the indoor oxygen concentration (%), B indicates the thermoelectromotive force of the thermocouple 3, and C indicates the CO/CO ₂ (%) of the stove. Further, D shows the change in the thermoelectromotive force of the thermocouple 3 when a gas that is difficult to burn during oxygen deficiency is combusted, and E shows the change in the thermoelectromotive force with a gas that is difficult to change (easily backfired). Further, F indicates the change in CO/CO ₂ (%) in the exhaust gas from the stove when the above gas E is combusted. G indicates the operating point of this implementation circuit. In this example, as will be explained later, in the case of the gas D, the A is 19.6.
(%), and in the case of gas E, the above A is 17.6 (%)
The combustion of the appliance is stopped. Also, at that point
CO/CO ₂ (%) is less than 0.005 (%) and is not harmful to the human body. H is CO/ which is a gas that is difficult to burn in the absence of oxygen.
Shows the dependence of CO ₂ on oxygen concentration. Also in the case of this gas
The value of CO/CO ₂ for 19.6 (%) oxygen concentration is
It is less than 0.005 (JIS standard), so there is no need to worry about CO poisoning.

From here, returning to Fig. 1 again to continue the explanation, gas is supplied to the main burner 1 and the oxygen deficiency detection burner 2 via the cooker 8, the solenoid valve 7, and the governor 6, thereby causing combustion of both. be exposed.

On the other hand, the electromagnetic valve 7 is excited by the thermoelectromotive force of the thermocouple 3 being processed by the upper control circuit. This control circuit is composed of a radio wave circuit I, an oscillation circuit, a timer circuit, a detection amplification circuit, and a rectification circuit. The voltage of the battery 10 is applied via a switch 9 to a transformer 12, a resistor 15, and a diode 1.
1. The AC voltage is stepped up as an AC voltage by the transistor 17, and this AC voltage is rectified by the next diode 13, resistor 14, and capacitor 16, and then stabilized to DC voltage by the Zener diodes 18 and 19.

The above oscillation circuit is PUT22, resistor 20,2
1, 23, 25 and a capacitor 24, and provides oscillation input to the next stage detection amplification circuit.
The detection amplification circuit has an operational amplifier 30 and a resistor 28,2.
It consists of 9,31. Now, when the thermoelectromotive force of the thermocouple 3 is generated at several tens of millivolts, that is, during the above-mentioned normal combustion, the thermoelectromotive force is applied to the resistor 29 and becomes a bias voltage. Then, the above oscillation input is added to this bias voltage, and the operational amplifier 3
It is amplified by 0 and transmitted to the next transformer 32.
However, when the thermoelectromotive force is less than 10 millivolts, that is, when there is a lack of oxygen in the top-up, the resistance is 2.
Since the bias voltage generated at 9 is low, operational amplifier 30 does not operate, and therefore no input is transmitted to transformer 32. Rectifier circuit V is diode 3
3. It is composed of a capacitor 34, and during normal combustion, the AC voltage from the transformer 32 is rectified to excite the solenoid valve 7. During oxygen deficiency, the transformer 32 does not operate, so the solenoid valve 7 is not excited. In addition, the timer circuit is switch 2 that turns on only when the ignition occurs.
6 and a capacitor 27. When igniting, the capacitor 27 is instantly charged by the power from the battery 10 and transformer 12 when the switch 26 is turned on, and this charging voltage operates the operational amplifier 30, and the thermocouple 3 is sufficiently heated to reach several tens of millivolts. In the meantime, an oscillation input from an oscillation circuit is applied to the operational amplifier 30, and thus a voltage is applied to the transformer 32. Therefore, the user does not have to keep the solenoid valve 7 open until the thermocouple 3 is sufficiently heated during ignition, which is convenient. Also, in normal conditions, if the combustion flame of the oxygen deficiency detection burner 2 fluctuates for some reason and as a result, the thermoelectromotive force temporarily drops below 10 millivolts, the capacitor 27 is discharged, and this causes the operational amplifier 3
Since a continuous voltage of 0 is applied, the solenoid valve 7 continues to be opened. Also, during normal combustion, the thermoelectromotive force of the thermocouple 3 is several tens of millivolts, so the voltage of the capacitor 27 is not discharged below this voltage, and as mentioned above, when the combustion flame fluctuates and detaches from the thermocouple 3, the thermoelectromotive force decreases. However, when the fluctuation disappears and the thermoelectromotive force recovers, it is charged again to the initial state voltage by the reverse leakage current of the diode 27' via the PUT 22 and the resistor 29.

On the other hand, when oxygen is deficient, the thermoelectromotive force decreases by several tens of degrees.
As it continues for more than a second, the charging current from the capacitor 27 eventually stops being discharged through the resistor 25, so the excitation of the solenoid valve 7 is stopped, and thereby the gas supply to the main burner 1 and the oxygen deficiency detection burner 2 is stopped. be done. As is clear from the above explanation, the time from the change in the combustion flame to the closing of the electromagnetic valve 7 is determined by the capacitance of the capacitor 27, and this time distinguishes between the above-mentioned fluctuations and oxygen deficiency. In addition, in order to stop the gas supply early, it is sufficient to stop the gas supply for about 10 seconds.

In addition, in the above embodiment, the main burner 1 is
Although an example has been described in which gas supply to both the main burner 1 and the main burner 1 is stopped, the present invention may be applied to a case where only the gas supply to the main burner 1 is stopped. Furthermore, although the thermocouple 3 is used as the sensor in the above embodiment, it may be a thermistor, a claim rod, or the like.

As described above, according to the present invention, the operation of the gas appliance does not stop even if the sensor temporarily detects a change in the combustion flame due to the influence of wind etc. caused by opening and closing the door, so it is convenient to use. Instead, in the event of an actual lack of oxygen, we will surely stop incomplete combustion of gas appliances,
It is highly safe because poisoning due to carbon monoxide can be prevented.

Further, according to the present invention, a timer at the start of use;
Since the circuit containing the same capacitor is used as the timer for flame swinging, it is not only reliable and inexpensive with fewer components, but also cannot be used from the beginning if the timer breaks down, so it can be used even if it is broken. This reduces the risk of oxygen deficiency accidents and greatly increases safety.

Furthermore, as gas is known to be prone to backfire, it may not lift up enough to shut off the gas circuit even in the event of an oxygen shortage, and this poses a safety problem. By varying the resistance values of the resistors 28 and 29 in the example, the sensitivity can be freely set, resulting in extremely high safety.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an electric circuit and a gas circuit of a gas appliance according to an embodiment of the present invention, and FIG. 2 is a characteristic diagram illustrating the operation of the gas appliance. 1... Main burner, 2... Oxygen deficiency detection burner,
3...Thermocouple (sensor).

Claims (1)

[Claims] 1 A sensor that detects changes in the combustion flame of the main burner, pilot burner, or oxygen deficiency detection burner when the gas appliance is deficient in oxygen, a capacitor that is charged at the start of ignition, and a discharge of this capacitor when the sensor starts up. Opening the gas supply valve to the burner with an electric current regardless of the operating state of the sensor, and charging the capacitor with the output of the sensor during normal combustion;
By discharging the capacitor while an oxygen deficiency or the like is detected by the sensor, at least the gas supply to the main burner is stopped when the combustion flame continues to change for a predetermined period of time or more. A gas appliance comprising a control circuit.