JPH0544573B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a control device for a piezoelectric ignition type gas stove.

Conventional configurations and their problems In recent years, in order to prevent tempura fires in kitchens, there has been a demand for the development of safety devices that can automatically extinguish gas stoves when tempura oil or the like overheats abnormally.

FIG. 1 shows a conventional control device for a piezoelectric ignition type gas stove. In FIG. 1, 1 is a thermocouple that is a flame sensor, and 2 is a safety valve, which is held by the electromotive force of the thermocouple 1. 4 is a dry battery and switch 5
The capacitor 3 is charged through the normally closed contact of the capacitor 3.

The operation of the piezoelectric ignition type gas stove control device configured as described above will be described below.

First, when the stove of the piezoelectric ignition type gas stove is closed, the capacitor 3 is charged to the electromotive force of the battery 4 through the normally closed terminal 5a of the switch 5 linked to the stove. Switch 5 is activated by opening the switch.
is switched to the normally open terminal 5b, the safety valve 2 is forcibly opened at the same time as the piezoelectric ignition, and due to the electric charge stored in the capacitor 3, the safety valve 2 is instantly held by suction, the gas is ignited, and the thermocouple 1 is Even if the electromotive force is generated by heating by the combustion flame and the electric charge in the capacitor 3 is discharged, the safety valve 2 can be held by suction. When the combustion flame disappears due to a misfire or the like, the electromotive force of the thermocouple 1 disappears, and the safety valve 2 closes to cut off the gas. However, the above configuration has a drawback in that it is not possible to prevent a fire in the tempura frying pan due to ignition of the tempura oil due to abnormal overheating of the tempura oil or the like.

Purpose of the Invention In view of the above drawbacks, the present invention is designed to automatically extinguish a gas stove in the event of abnormal overheating of tempura oil, etc., in order to prevent not only gas leakage or disconnection in the event of a misfire, but also tempura fires in the kitchen. The present invention provides a control device for a piezoelectric ignition type gas stove that can shut off gas when the set temperature is reached by comparing an arbitrary set voltage with the voltage of a temperature sensor.

Structure of the Invention In order to achieve the present invention, the present control device includes a dry battery, an operation switch, an oscillation circuit that serves as a reference for the control device, a flame detection circuit that generates a pulse output due to the electromotive force of the thermocouple, and a flame detection circuit that generates a pulse output due to the electromotive force of the thermocouple. an ignition timer circuit that holds the safety valve until the electromotive force is sufficiently built up; a pulse voltage comparison circuit that compares the three-value reference voltage generated by the output of the flame detection circuit with the voltage of the temperature sensor; and the voltage of the temperature sensor. and an arbitrarily settable voltage; a NAND circuit whose inputs are the inverted output of the temperature notification voltage comparison circuit and the output of the pulse voltage comparison circuit;
A NAND circuit receives the output of this NAND circuit and the output of the ignition timer circuit as input, and the output of this NAND circuit rectifies the secondary output of the Palma transformer driven by the transistor, and the DC- A DC converter circuit, an inverting circuit of the DC-DC converter circuit, an alarm timer circuit whose OR input is the output of the inverter circuit and the output of the temperature alarm voltage comparison circuit, and an intermittent alarm circuit whose input is the output of the alarm timer circuit. It consists of an oscillation circuit, a battery check circuit that notifies battery consumption, and a buzzer drive circuit that OR-inputs the output of the intermittent oscillation circuit and the output of the battery check circuit.

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

FIG. 2 shows a control device for a piezoelectric ignition type gas stove according to an embodiment of the present invention. 1 is a dry battery, 2 is an operation switch that is linked to a switch that opens and closes the fuel supply path of the piezoelectric ignition type gas stove, and 3 is a control device for a piezoelectric ignition type gas stove according to an embodiment of the present invention. An oscillation circuit serving as a reference for this control device, 8 an ignition timer circuit, 15 a flame detection circuit, 29 a pulse voltage comparison circuit, 35, 35 a NAND circuit, and 37 a DC-DC converter for holding a safety valve. circuit,
52 is a battery check circuit, 57 is a temperature notification voltage comparison circuit, 72 is a notification timer circuit, and 87 is a buzzer circuit.

Opened Kotoku, a piezoelectric ignition type gas stove (hereinafter referred to as “Kotoku”)
When the power is turned ON), power is supplied from the dry cell battery 1 by the operation switch 2 in conjunction with this, and the oscillation circuit 3 starts oscillation, which is the reference of this control device. The oscillation circuit 3 includes inverters 4, 7, a resistor 5,
It consists of a capacitor 6. Next, when the operation switch 2 is turned on, the capacitors 11 and 12 are charged through the resistors 9 and 10. The output of the ignition timer circuit 8 becomes a pulse during the charging time up to the threshold voltage _VTH . This state is shown in Figure 3.
It is between _t1 and _t2 . Assuming that no electromotive force is generated in the thermocouple 21, which is a flame sensor, the flame detection circuit 1
The output of transistor 5 becomes the power supply voltage V _DD and transistor 30
becomes OFF, and the input voltage of voltage comparator 33 becomes
V1=R ₃₂ /R ₃₁ +R ₃₂・V _DD , but the input voltage becomes V2=R ₆₇ /R ₆₄ +R ₆₇・V _DD , and since no electromotive force is generated in the thermocouple 21, V2>V1 and this pulse The output of the voltage comparison circuit 29 becomes V _L , and the output of the NAND circuit 35 becomes V _H regardless of other input signals. Other input signals are the temperature notification voltage comparison circuit 57
This output is obtained by the combination of resistors 58, 59, 60 and variable resistor 61, and this voltage and resistor 6
4 and the voltage divided by the temperature sensor 67 using a voltage comparator 68. As described above, since no electromotive force is generated in the thermocouple 21, the input voltage of the voltage comparator 68 is higher than the input voltage, and the output of the temperature notification voltage comparison circuit 57 becomes _VL . This output is inverted by an inverter 70,
It serves as an input to the NAND circuit 35.

The output of the NAND circuit 36 which receives the output of the NAND circuit 35 and the output of the ignition timer circuit 8 becomes a pulse output while the output of the ignition timer circuit 8 is a pulse, and the output is a pulse output when the output of the ignition timer circuit 8 is a pulse.
DC-DC converter circuit 3 for supplying voltage to hold safety valve 47 forcibly attracted by ON
The switching transistors 42 and 43 of No. 7 are driven, and a pulse voltage is generated on the secondary side of the pulse transformer 44, rectified by the transistor 45, smoothed by the capacitor 48, and supplied to the safety valve 47. Resistance 38, 40, 41, 4
6 is a current limiting resistor, and resistor 39 is a base-emitter resistor of transistor 43. The output of the ignition timer circuit 8 is during the pulse, that is, the time t ₁
~ _t2 , if no electromotive force is generated in the thermocouple 21, the output of the ignition timer circuit 8 becomes _VH at time _t3 ,
The output of the NAND circuit 36 becomes _VL , which makes it impossible to drive the DC-DC converter circuit 37, no voltage is generated on the secondary side of the pulse transistor 44, the safety valve 47 is turned off, and the gas is immediately cut off.
The voltage across the safety valve 47 becomes zero, the output of the inversion circuit 49 becomes _VH , and the notification timer circuit 72
The capacitor 80 is charged, a voltage is generated across the resistor 81, and the NAND circuit 83 of the intermittent oscillation circuit 82 is charged.
only for a time higher than the threshold voltage V _+H of
The output of the intermittent oscillation circuit 82 oscillates and the buzzer 92
can sound.

Next, when an electromotive force is generated in the thermocouple 21 between time _t1 and _t2 , the voltage comparator 26 of the flame detection circuit 15
The input voltage of V _H = R ₁₈ / R ₁₆ + R ₁₇ + R ₁₈ · V _DD (dotted line A in Figure 4) becomes V _L = 0 due to the oscillation circuit 3, and the electromotive force of the thermocouple 21 becomes
R ₁₇ /R ₁₆ +R ₁₇ +R ₁₈ ·V _DD or more, and the output of the voltage comparison circuit 26 becomes a pulse with the load resistors 27 and 28 as a load. FIG. 4 shows this state.
Note that the dotted line has a relationship of R ₁₇ +R ₁₈ /R ₁₆ +R ₁₇ +R ₁₈ ·V _DD .

Therefore, the output of the flame detection circuit 15 also becomes a pulse, and the output of the ignition timer circuit 8 ceases to be a pulse. In other words, even after time _t2 , the output of the NAND circuit 36 becomes a pulse, which drives the DC-DC converter 37 and closes the safety valve. It becomes possible to continue holding 47. Next, when the temperature sensor 67 is heated by the combustion flame, the input voltage of the voltage comparator 68 becomes lower than the input voltage that can be set arbitrarily by the variable resistor 61, so the output of the voltage comparator 68 is V _L
→ V _H , the input of the NAND circuit 35 becomes V _L by the inverter 70, and the output of the NAND circuit 35 becomes V _H. Therefore, the output of the NAND circuit 36 becomes _VL , the DC-DC converter circuit 37 is not driven, and no voltage is generated on the secondary side of the pulse transformer 44, so the safety valve 47 is turned off and combustion can be stopped.

Further, the battery check circuit 52 turns off the transistor 56 when the divided voltage of the resistor 54 and the resistor 55 becomes lower than the base-emitter voltage of the transistor 56 due to battery consumption.
The output of the buzzer drive circuit 87 becomes _VH , and the output of the buzzer drive circuit 87 also becomes _VH , causing the buzzer 92 to sound continuously, thereby notifying the user that the battery is exhausted.
The thermistor 53 is for temperature maintenance.

The pulse voltage comparator circuit 29 is for turning off the safety valve 47 at time t ₂ when the temperature sensor 67 opens or shoots out.

Effects of the Invention As explained above, according to the piezoelectric ignition type gas stove control device of the present invention, combustion can be automatically stopped at a temperature set arbitrarily by the user (approximately 50°C to 250°C), and When tempura oil etc. is abnormally overheated (approximately
It not only prevents fires by automatically stopping combustion at a temperature of 250°C (set at 250°C), but also saves energy by preventing unnecessary overheating.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a conventional piezoelectric ignition type gas stove control device, Fig. 2 is a circuit diagram of the same device according to a certain embodiment of the present invention, and Fig. 3 is a timer diagram showing input and output waveforms of an ignition timer circuit. Figure 4 is a time chart showing the input/output status of the voltage comparator of the flame detection circuit. DESCRIPTION OF SYMBOLS 1... Dry battery, 2... Operation switch, 3... Oscillator, 8... Ignition timer circuit, 15... Flame detection circuit, 29... Pulse voltage comparison circuit, 35, 36...
...NAND circuit, 37...DC-DC converter circuit, 52...Battery check circuit, 57...Temperature notification voltage comparison circuit, 70...Inverter, 72...
Notification timer circuit, 82... Intermittent oscillation circuit, 87...
...buzzer drive circuit.

Claims (1)

[Claims] 1 A dry battery, an operation switch, an oscillation circuit that serves as a reference for the control device, a flame detection circuit that uses a thermocouple as a flame sensor and generates a pulse output due to the electromotive force of the flame sensor, and a flame detection circuit that uses a thermocouple as a flame sensor to generate a pulse output. An ignition timer circuit that holds the safety valve until the temperature rises, a pulse voltage comparison circuit that compares the three-value reference voltage generated by the output of the flame detection circuit and the temperature sensor voltage, and a voltage that can be set arbitrarily with the temperature sensor voltage. a temperature alarm voltage comparator circuit that compares the voltage with the pulse voltage comparator circuit;
A NAND circuit that receives the output of the NAND circuit and the output of the ignition timer circuit as input, and a DC that is driven by the output of this NAND circuit and rectifies the secondary output of the pulse transformer with a transistor and maintains the safety valve.
- a DC converter circuit, an inverting circuit of this DC-DC converter circuit, a notification timer circuit whose output is an OR input of the output of this inversion circuit and the output of the temperature notification voltage comparison circuit, and whose input is the output of the notification timer circuit; A control device for a gas stove comprising an intermittent oscillation circuit for detecting battery consumption, a battery check circuit for notifying battery consumption, a buzzer drive circuit for ORing the output of the intermittent oscillation circuit and the output of the battery check circuit, and a buzzer.