JPS6033424A - Combustion safety device - Google Patents

Abstract

PURPOSE:To obtain an inexpensive safety device capable of securing safety of overheating upon cooling ''tempura'' or the like and detecting blow out of flame by the same controller by a method wherein an electronic circuit is equipped in the device and a solenoid valve is excited by the oscillating output of the comparator of a thermocouple and a heat sensitive element. CONSTITUTION:When the thermocouple 5 is heated by the flame, the oscillating output, obtained by the generation of thermoelectromotive force, is transmitted to ''tempura'' overheat detectors 24-28. The heat sensitive element 4 transmits the oscillation by the comparator 29 when temperature is lower than the ignition temperature of ''tempura'' oil but transmits the oscillation thereof when the temperature becomes higher than the ignition temperature of the same. when there is combustion flame, the oscillating output oscillates a transformer 30 to hold the opening of the solenoid valve 2 after rectifying the output by a diode 31 and a capacitor 32 in case the temperature of the ''tempura'' oil is lower than 250 deg.C, however, the transformer 30 is not oscillated, the solenoid valve 2 is not held opened and the trouble of the device may be prevented when the blow out of the flame is happened or the temperature of ''tempura'' oil has become higher than 250 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a safety device for a combustor that uses gas or oil as fuel.

Conventional configuration and its problems With conventional gas stoves, for example, when cooking tempura, etc., if the user accidentally leaves the cooking area while cooking, the temperature of the tempura oil may drop.
There are many cases in which the oil vapor rises and ignites, resulting in a fire.

Many ideas have been made to prevent this, but they have not been put to practical use because of the need to ensure safety in the event that the preventive device fails, and the cost of such devices.

In addition, there is a thermocouple safety device to prevent raw gas from leaking and igniting the leaked gas if the combustion flame blows out due to the influence of wind while using a gas stove, resulting in a fire or explosion. This is a structure in which the thermoelectromotive force is directly used to hold the solenoid valve, and it takes time for the thermocouple to heat up sufficiently, and in order to take the power from the thermoelectromotive force, its resistance value must be lowered, which increases costs. Ta.

Purpose of the invention - 3 Pages The present invention solves the above-mentioned conventional drawbacks, and provides a safe and inexpensive safety device that ensures 3E safety when overheating of top plastics, etc., and also detects blowout with the same control of 91Hg. intended.

Structure of the Invention In order to achieve the above object, the combustion safety device of the present invention uses a thermocouple and a heat-sensitive element as a sensor, and uses the output of an oscillator to detect the detection by oscillating a resistive connection connected in series between power sources. At the same time, a thermocouple is connected to a connection point with a potential difference of several millivolts from that voltage, and a comparison is made.A thermosensitive element and a resistor are connected in series, oscillated, and compared, and the output is taken out as oscillation to excite a solenoid valve. This configuration allows a series of oscillation systems to be used as a circuit to prevent accidents caused by overheating or blow-out of the top plastic, etc., and because it compares the voltages of the same resistor series without an amplification circuit, the cost I/I is low and noise is reduced. It is also stable and has the effect of being safe even in the unlikely event of an open-short failure in the resistor or comparator.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is a gas cock, 2 is a solenoid valve, 3 is a burner, 4 is a SiC thermistor which is a heat sensitive element, and 5 is a thermocouple.

6 is a power supply, 7 is a switch linked with gas cock 1, 8
9 is a diode, 9 is an LED, 10 is a resistor, and 11 is a capacitor. 12, 13, 14° 15.16 is resistance,
17 is a capacitor, and 18 is a comparator, which constitute an oscillation circuit.

19 is a comparator, 20, 21.22 are resistors connected in series between the power supplies, and 23 is a comparator that compares the connection between the thermocouple and the resistors 21.22. These constitute a thermoelectromotive force detection circuit.

24.25 is a resistor connected in series with the heat sensitive element 5; 26.
27 and 28 are resistors for setting a reference voltage, and 29 is a comparator that compares the connection between the heat sensitive element 4 and the resistor 24 with the reference voltage, and these are used to detect overheating of the top plate. 30 is a transformer, 31 is a diode, 32 is a capacitor, and 33 is a solenoid which is assembled into the electromagnetic valve 2 and is installed in 5 units.

The operation of the above configuration will be explained below.

First, when the gas cock 1 is turned and held, the solenoid valve 2 is forcibly opened and ignited. (The ignition circuit and the circuit and mechanism for forcibly opening the solenoid valve 2 are not shown.) When the switch 7 linked to the gas cock 1 is closed and energized, the oscillation circuit oscillates.

The oscillation output is shaped by a comparator 19 and causes a resistor 21 and a connecting portion 22 connected in series between the power supplies to oscillate.

Therefore, the connection between resistors 20 and 21 oscillates at a voltage several mV higher than that. When the thermocouple 5 is not heated, the θ terminal of the input to the comparator 23 is always high and the output is L, but when the thermocouple 5 is heated by the flame, the O terminal temporarily becomes ■.
An output that is lower than the connection of the terminal resistors 21 and 22 indicates oscillation. (Even if the output of the comparator 19 oscillates and becomes L, it does not become completely OV.) At this time, even if noise enters between the power supplies, it enters the same resistor series 20, 21° 22, so it is output in the same phase. can be ignored, making it resistant to noise.
It is possible to detect 6 bases of several mV without increasing the width. Even if any of the resistors 20 to 28 is open-shorted or if the comparators 18, 19, 23.degree. 29 are out of order, the output will not oscillate.

Next, the oscillation output obtained by the generation of thermoelectromotive force is transmitted to the next-stage ceiling-top overheat detectors 24-29. In the case of the SiC thermistor of this embodiment, the heat-sensitive element 4 has a resistance of 700 Ω at normal temperature, and 60 Ω at a safe temperature of 250°C, where frying oil ignites.
The resistor 24 and the resistor 26 that creates the reference voltage,
By setting 27.28, oscillation is transmitted by the comparator 29 when the temperature is 60Ω or more, that is, below the temperature at which the baking oil ignites, and when the temperature is higher than that, oscillation is transmitted. If the value of resistor 26 plus resistors 27 and 28 is chosen to be the same, then if resistor 24 is set to 60Ω, then if the SIC thermistor is less than 60Ω, the ■ terminal of comparator 29 will always be higher than the O terminal and the output will be does not oscillate. Also resistance 25
If the value of is IMΩ, then the SiC sensor is 1MΩ.
In the above case (broken wire), oscillation still does not occur. Therefore, disconnection and short circuit of resistor 7-base SiC sensor 4 in the same column, and constituent resistor 24
It is safe because it does not oscillate even when the comparator 29 is open-shorted or the comparator 29 fails.

When there is a combustion flame or when the temperature of the cooking oil is below 250°C, the oscillation output causes the transformer 30 to oscillate and is rectified by the diode 31 and capacitor 32 to keep the solenoid valve 2 open. Disappears or temperature of tempura oil is 250℃
When the temperature exceeds °C, the transformer 30 does not oscillate and the solenoid valve 2
These accidents can be prevented by not keeping them open.

Effects of the Invention As described above, according to the present embodiment, accidents such as raw gas leakage caused by flames and blowouts of the ceiling can be prevented without compromising the safety caused by failure of the safety device.

In addition, the sensor that detects blow-out does not require current to keep the electromagnetic valve attracted as in the past, and only detects voltage changes, making it cheaper and faster to respond.

Furthermore, since detection is performed using resistors in the same column, malfunctions due to noise≧K can be prevented, reliability is high, and safety in the event of an open/short circuit is ensured. In addition, since they are constructed using the same oscillator, the overall cost is low and there is an effect that a highly safe device can be put into practical use.

[Brief explanation of the drawing]

The figure is a configuration diagram showing a case where a combustion safety device according to an embodiment of the present invention is applied to a gas stove. 4...Thermosensitive element, 5...Thermocouple, 18.
...Comparator, 20.21.22...
resistance. Name of agent: Patent attorney Toshio Nakao and one other person

Claims (1)

[Claims] A thermocouple that detects the combustion flame of a burner of a combustion cooking appliance, a heat-sensitive element placed in close contact with the bottom of the jl-RB to be cooked, and a solenoid valve placed in a fuel passage. and an electronic circuit that controls a solenoid valve using the thermocouple and the heat-sensitive element. The thermocouple is connected to a connection part with a voltage difference, and the wire of the other thermocouple and the connection part of the resistor are compared with a comparator, and the thermosensitive element and two other resistors are connected in series. The combustion safety device is configured to connect the thermocouple and the thermosensitive element to oscillate, compare the connection between the thermocouple and the resistor with a reference voltage, and excite the electromagnetic valve by the oscillation output of the comparator of the thermocouple and the thermosensitive element. 2 pages