JPS6161012B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combustion safety device for gas, oil, etc., which is economical, extremely safe, and highly practical.

Some conventional combustion safety devices utilize fuel cell-type combustion sensors such as oxidized zirconia. This utilizes the fact that porous electrodes such as platinum electrodes are provided on both sides of a cylindrical solid electrolyte such as zirconia oxide, and the electromotive force changes due to the difference in oxygen concentration between the inner and outer surfaces of the cylinder.
It was very convenient because it stopped the combustion when the combustion equipment was incompletely burned, but because of its cylindrical shape, the inner surface was easily clogged with soot and dust, which caused the problem that it did not work properly and was unsafe. It was hot.
In addition, since the electrodes are constantly exposed to high temperatures, they need to be made of durable materials, and require precious metals such as platinum, resulting in high costs and poor widespread use economically. Furthermore, although oxide semiconductor sensors are superior in this respect, they are susceptible to disconnection and short-circuit failures, and if used in a malfunctioning state, it may lead to an accident, resulting in poor safety.

An example in which the configuration of the present invention is applied to a gas appliance will be explained. Figures 1A and 1B show the characteristics of titanium oxide, which is a combustion sensor. The A-axis shows the oxygen concentration in the room, and the B-axis shows the sensor resistance value at around 800℃.
For example, when the oxygen concentration is 19%, the sensor resistance is 1KΩ, so if the control circuit is configured to stop combustion when the sensor resistance becomes 1KΩ or less, incomplete combustion due to oxygen deficiency can be prevented. Further, the C-axis shows the temperature of the combustion sensor, and the D-axis shows its resistance value. During normal combustion, the combustion sensor reaches 800℃ due to the combustion flame.
Therefore, if the combustion is stopped when the temperature reaches 500KΩ or more, it is possible to prevent flames, explosions, etc. due to the outflow of raw fuel even in the event of a burnout. In this graph, explanation was made using titanium oxide, but
Reduced semiconductors such as WO ₃ and Fe ₂ O ₃ MO also exhibit similar properties. It is known that these semiconductors are generally oxidized or reduced and their resistance values change depending on the surrounding oxygen partial pressure. Furthermore, even at the same oxygen pressure, similar properties are exhibited when gases such as CO, H ₂ , smoke, etc. are generated in the atmosphere. That is, TiO ₂ →TiO+
O reaction occurs and electrical resistance changes.

FIG. 2 shows the entire invention. The gas circuit includes a main cock 38, a solenoid valve 37, a nozzle 35, and a burner 33.
Consists of. There are 34 combustion sensors made of titanium oxide inside the burner, and the main switch is equipped with a power switch 1 for the control circuit and a timer switch 2 that is temporarily turned on at the time of starting operation. 4 indicates a dry battery. The control circuit consists of a timer, an oscillator, a comparator, etc. The timer consists of diodes 7 and 9, resistors 3, 5, 8, and 11.
The first stage consists of 6.10 capacitors. The oscillator has 16 comparators 12, 13, 14, 1
It is composed of resistors 5, 18a, and 18b and capacitors 19. Furthermore, an amplitude voltage is configured by dividing these resistances. The comparator is composed of a comparator 27, resistors 24, 25, and comparators 17, 22, and resistors 20, 21, 23. Further, as a solenoid valve drive circuit, a transistor 28, a resistor 26,
29, a transformer 30, a diode 31, and a capacitor 32.

The above configuration will be explained in detail in the order of operations. first,
At the same time as the main cock 38 is opened, the solenoid valve 37 is manually opened to ignite. (The ignition part is not shown) Then, the power switch 1 linked with the main switch
is closed, the control circuit is energized, and the timer switch 2 instantly charges up the capacitor 10. During normal operation, the capacitor 6 is hardly charged by the resistor 3. On the other hand, the charge charged in the capacitor 10 is gradually discharged through the resistors 8 and 11 and reaches the comparator 22 at the same time. Also, comparator 1
The oscillator 6 starts oscillating, and the oscillation voltage is transformed by the comparator 17 and resistors 20, 21, and 23 and reaches the comparator 22. While the discharge voltage of the capacitor 10 is within the amplitude voltage range of the oscillator, the output of the comparator 22 shows an oscillation output, causing the transistor 28 to oscillate, and is coupled by the transistor 30, rectified by the diode 31 and capacitor 32, and outputs the solenoid 36. The magnet is energized, and the solenoid valve 37 is kept open. Therefore, at the beginning of combustion, the detection delay of the combustion sensor 34 is covered by the discharge potential of the capacitor 10. During this time, the combustion sensor is sufficiently heated and the resistance value reaches the specified value.
500KΩ or less, the solenoid valve is excited by the comparator 27 using a transistor or the like as described above, and combustion continues. That is, when the voltage determined by the resistor 25, the combustion sensor 34, and the resistor 24 becomes less than the upper limit of the oscillation voltage determined by the resistance value of the comparator 16, the output of the comparator 27 starts oscillating, and the solenoid valve 37 opens. is retained. At this point, remove the timer section, and manually operate the solenoid valve 3.
It is also possible to perform the opening and holding of item 7 manually.
If the combustion flame blows out for some reason during combustion, the combustion sensor 34 will stop being heated by the combustion heat, so the resistance value will become more than the predetermined value of 500KΩ.
The oscillation of the comparator 27 is stopped, the solenoid valve is closed, and gas outflow is prevented. Furthermore, if combustion is continued for a long time in a closed room, the oxygen concentration will drop and gas poisoning will occur due to incomplete combustion, but according to the present invention, when the oxygen concentration drops, the resistance value of the combustion sensor will decrease to about 1KΩ as mentioned above. The voltage determined by the resistor 25 and the like becomes lower than the lower limit of the oscillation voltage of the comparator 16, and the output of the comparator 27 stops oscillating. Therefore, combustion is stopped and accidents caused by incomplete combustion can be prevented.

In addition, if the timer switch 2 fails for some reason and remains closed, the capacitor 6 is gradually charged and the diode 9 stops the oscillation of the oscillator, so the solenoid valve 37 is not kept open as described above. A switch failure is a safety failure. Furthermore, failure of any of the circuit components constitutes a safe failure in the control circuit of the present invention. For example, if the resistance value of the oscillator becomes an open failure, since both resistors are necessary for oscillation, the oscillation will stop or the oscillation frequency will become abnormally high, causing the solenoid valve 37 to stop. The value is not required for open maintenance. Furthermore, in the present invention, since the amplitude voltage of the oscillator is configured by resistor division, it is possible to compare the voltage of the combustion sensor 34 with very high accuracy, and as mentioned above, oscillation is prevented in the event of an open or short failure. Since it stops, no voltage is generated on the secondary side of the transformer 30 and the solenoid valve 37 does not continue to be opened. Even when the short of the transistor fails, the oscillation stops or the oscillation frequency increases and does not reach the value necessary to keep the solenoid valve 37 open. Furthermore, in the present invention, since the amplitude voltage of the oscillator is divided by resistance, the electromagnetic valve will not be kept open due to a short failure of the oscillator. (It is generally believed that there is no short resistance failure.)
Even when the short of the transistor 28 fails, the transformer is not energized and the solenoid valve 37 does not remain open.
In addition, when the combustion sensor 34 has an open failure, the resistance value becomes 500KΩ or more, and when the short circuit failure occurs, the resistance value becomes 500KΩ or more.
Since it is less than 1KΩ, the solenoid valve 37 is not opened as described above and is safe. In this embodiment, only gas appliances have been described, but the present invention can also be applied to other combustion appliances such as petroleum appliances.

Therefore, according to the present invention, there is no need for an expensive combustion sensor as in the past, and since the sensor is inexpensive, it is economical and has high popularity. Furthermore, since it does not require a cylindrical shape, it is highly safe as it does not collect soot or dust. In the event of a failure in the control circuit or combustion sensor, it will be a safe failure and can be used with peace of mind.

[Brief explanation of the drawing]

1A and 1B are characteristic diagrams of a combustion sensor used in the present invention, and FIG. 2 is a circuit diagram of a combustion safety device in an embodiment of the present invention. 16... Comparator, 24... Resistor, 30...
...trans, 35... nozzle.

Claims (1)

[Claims] 1. A combustion sensor made of an oxide semiconductor or the like whose resistance value changes depending on the combustion state when receiving the exhaust and exhaust heat of the combustion flame of the combustion appliance, a combustion stop device installed in the combustion passage that forms the combustion flame, and the combustion sensor A control circuit that detects the resistance value of the sensor and opens and closes the combustion stop device, and compares the signal of the combustion sensor with the oscillation voltage of an oscillator in which the amplitude voltage is divided by resistance in the control circuit. A combustion safety device characterized by having a safety device.