JPH06174228A - Gas control circuit for hot plate - Google Patents

Abstract

PURPOSE:To readily and positively perform a temperature control so as to prevent outflow of gas due to going-out and fire catching of oil. CONSTITUTION:There are provided a thermocouple 4 which is heated by flame to generate an electromotive force, a safety valve 24 adapted to be kept open by the electromotive force of the thermocouple 4, a reverse thermal fuse 13 which serves for detecting a temperature of a pan bottom and shifts from a non-conducting condition to a conducting condition at temperatures above a predetermined temperature, and an electric source 5 for applying an impressed voltage caused by the thermocouple 4 and a voltage of reversed polarity to the safety valve 24 through the reverse thermal fuse 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas control circuit for controlling the flow of gas in a gas stove.

[0002]

2. Description of the Related Art In a gas stove, a thermocouple heated by a flame and a safety valve held open by an electromotive force generated by the thermocouple are provided in order to prevent gas from flowing out in the case of extinction. Conventionally, there has been provided a device which shuts off a gas by closing a safety valve when the extinguishing occurs.

In addition, in recent years, in consideration of the occurrence of fire due to the ignition of the tempura oil, a heat collecting plate is provided in contact with the bottom of the pan, and a mechanical switch using bimetal is attached to the heat collecting plate. It is provided that the safety valve is connected between the thermocouple and the safety valve so that when the pot bottom temperature exceeds a predetermined value, the switch is turned off and the safety valve is closed.

[0004]

However, since the switch has a mechanical contact and has a large electric resistance, it may be difficult to open the safety valve when the electromotive force of the thermocouple is small. there were. Further, since this contact is under severe heat conditions, there is an increase in electrical resistance due to corrosion, which easily causes the above problems. Due to the structure, there is also a problem that the detected temperature tends to vary.

The present invention has been made in view of the above points, and an object thereof is to easily and surely perform temperature control for preventing outflow of gas due to extinguishment and prevention of oil ignition. It is possible to provide a gas control circuit for a gas stove.

[0006]

DISCLOSURE OF THE INVENTION In the present invention, however, a thermocouple that generates an electromotive force by being heated by a flame, a safety valve that is held in an open state by the electromotive force of the thermocouple, and a temperature detection of the pot bottom. And a reverse temperature fuse that switches from a non-conducting state to a conducting state when the temperature exceeds a predetermined temperature, and a power supply that applies a voltage applied by a thermocouple and a reverse polarity voltage to the safety valve through the reverse temperature fuse. It is characterized by consisting of and.

[0007]

According to the present invention, the reverse temperature fuse does not affect the operation of the safety valve due to the non-conduction state of the reverse temperature fuse in the normal state, and if the temperature of the bottom of the pot exceeds the predetermined temperature, Since the reverse temperature fuse becomes conductive and a voltage of the opposite polarity to the voltage due to the electromotive force of the thermocouple is applied to the safety valve, the current due to the electromotive force of the thermocouple and the reverse current flow to the safety valve. The safety valve is surely shut off to extinguish the fire.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the illustrated embodiments. A nozzle 23 is provided at one end of the mixing tube 20, and a burner cap 21 is attached to the other end of the mixing tube 20 to provide a burner. Flame holes 22 are arranged on the periphery of the cap 21. Then, in the gas flow path leading to the nozzle 23,
An electromagnetic safety valve 24 is provided.

A thermocouple 4 heated by a flame is arranged near the burner cap 21. Also,
At the center of the burner cap 21, the temperature detecting unit 1 for detecting the temperature of the bottom of the pan is arranged. The temperature detection unit 1 includes a shaft 10 supported by a fixed plate 15 attached to a mixing tube 20, a cylinder 11 that is vertically movable with respect to the shaft 10, and a heat provided at the upper end of the cylinder 11. The reverse temperature fuse 13 attached to the lower surface of the protective cover 12 made of a good conductor is disposed between the upper end of the shaft 10 and the lower surface of the protective cover 12, and biases the protective cover 12 and the cylinder 11 upward. And a spring 14 formed of a coil spring.

The reverse temperature fuse 13 here is in a non-conducting state at room temperature and transitions from the non-conducting state to the conducting state when the temperature exceeds a predetermined temperature. For example, as shown in FIG. 2, it is made of an insulating material. The base 15 is covered with a heat collecting plate 16, and a pair of contact portions 17, 17 are projected from the base 15 in a space surrounded by the both, and the lower surface of the heat collecting plate 16 is contacted with the contact portions 17, 17. The heat collecting plate 16 is attached to the lower surface of the protective cover 12 by attaching solder 18 so as not to do so. As the solder 18 which is a tin-lead alloy, one having a melting point of 250 to 300 ° C. is used.

The upper surface of the protective cover 12 in the temperature detecting portion 1 is in contact with the bottom surface of the pan 3 by the biasing force of the spring 14, and the temperature of the bottom surface of the pan 3 is higher than a predetermined temperature (for example, 300 ° C.). When this happens, this temperature is the protective cover 1.
2 is transmitted to the solder 18 via the heat collecting plate 16 and the solder 1
8 melts and flows downward, and as shown in FIG. 2B, the solder 18 accumulated downward makes the contact portions 17, 17 electrically conductive.

As shown in FIG. 1, the reverse temperature fuse 13 is connected to a safety valve 24 in parallel with the thermocouple 4 and a DC power source 5 such as a battery is connected in series. Here, the DC power supply 5 is the reverse temperature fuse 1
It is connected so that a voltage having a polarity opposite to the voltage applied by the electromotive force by the thermocouple 4 is applied to the safety valve 24 when 3 becomes conductive. The DC power supply 5 has a voltage higher than the voltage generated by the electromotive force of the thermocouple 4.

However, when the gas stove 2 is ignited, since the reverse temperature fuse 13 is not conducting at this time, only the electromotive force generated by the thermocouple 4 is applied to the safety valve 24 and the safety valve 24 is opened. Hold. And
If the bottom surface temperature of the pot 3 rises above a predetermined temperature, the reverse temperature fuse 13 becomes conductive, so the safety valve 2
4, a voltage having a polarity opposite to that of the voltage applied by the thermocouple 4 is applied by the DC power supply 5 and the current flow is reversed. At the time of this reversal, there is a moment when the current value flowing through the safety valve 24 becomes zero. To do so, the safety valve 24 closes to shut off the gas flow and extinguish the fire.

During normal combustion, the reverse temperature fuse 1
Although 3 does not affect the open holding of the safety valve 24 by the thermocouple 4, the safety valve 4 is surely closed when the bottom of the pot is overheated. As the reverse temperature fuse 13, the one using the solder 18 is shown in the above embodiment, but a thermistor having a negative characteristic (preferably a critical temperature thermistor) having a large change in resistance value around 300 ° C. or an equivalent temperature- Those having resistance characteristics can be used.

[0015]

As described above, according to the present invention, the reverse temperature fuse for detecting the temperature of the bottom of the pot and which shifts from the non-conducting state to the conducting state when the temperature exceeds the predetermined temperature is
It does not affect the open holding of the safety valve in the thermocouple during normal combustion, and since it is equipped with a power supply for applying the reverse polarity voltage and the voltage applied by the thermocouple to the safety valve through the reverse temperature fuse, When the abnormal overheat is detected, the safety valve is surely shut off, and the temperature control for preventing the gas outflow and the oil ignition due to the extinction can be easily and surely performed.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment.

FIG. 2 is a cross-sectional view of the above thermal fuse, showing (a)
FIG. 3B is a cross-sectional view of a non-conductive state and FIG.

[Explanation of symbols]

 4 Thermocouple 13 Reverse temperature fuse 24 Safety valve

Claims (1)

[Claims] 1. A thermocouple that generates an electromotive force by being heated by a flame, a safety valve that is held in an open state by the electromotive force of the thermocouple, and a temperature for detecting the temperature of the bottom of the pan and a temperature higher than a predetermined temperature. The gas stove characterized by comprising a reverse temperature fuse that shifts from a non-conducting state to a conducting state, and a power source that applies a voltage applied by a thermocouple and a reverse polarity voltage to the safety valve through the reverse temperature fuse. Gas control circuit.