JPH03291417A - Overheat preventive heater - Google Patents

Abstract

PURPOSE:To quicken firing and to improve reliability at the time of ignition in an overheat preventive heater for a gas cooker by controlling power supply to an electromagnet which controls heating of a heating part based on the temperature of a cooking container. CONSTITUTION:If abnormal heating occurs, a switch of a bimetal 11 working as a temperature sensor turns OFF, a current-limiting element 17 OFF and another current-limiting element 18 ON. Then discharge current 22 from a condenser 19 which is opposite in phase to generating current 21 from a thermoelectric couple 4 flows from the condenser 19 through an exciting coil 13 and the current-limiting element 18. Therefore opposite phase separating force by the discharge current becomes larger than attracting force by the generating current, and a switch valve separates to interrupt gas supply. Thus an overheat preventing heater in which firing is quick and reliability is high can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an overheat prevention stove such as a gas cooker, and more particularly to a gas cooker equipped with an extinguishing safety device and an overheat prevention safety device.

2. Description of the Related Art Conventionally, this type of overheating prevention stove has been developed, for example, by the
As shown in Publication No. 132003, a thermostand for detecting the wall temperature of the cooking container is provided in the closed circuit of a safety device consisting of a thermocouple and an electromagnet, and the electrical settings of the thermostand are opened and closed. The stove was designed to prevent overheating.

Problems to be Solved by the Invention In such conventional overheating prevention stoves, the electrical contacts are kept at a high temperature all the time, which increases contact resistance, or due to the routing of electric wires, a safety device is installed to turn off the ignition. The problem was that the operation was slow and it was difficult to ignite.

The present invention solves the above-mentioned problems, and aims to provide an overheating prevention stove that ignites quickly (and is highly reliable) at the time of ignition.

Means for Solving the Problems In order to achieve the above object, the present invention includes a heating section that heats a cooking container, a magnet that controls the heating of the heating section, and a magnet that is heated by the heating section and supplies an electric current to the electromagnet. a thermocouple to supply, a temperature sensor that detects the temperature of the cooking container;
The configuration includes a power supply.

Operation Since the present invention has the above-described configuration, by supplying a current from the power source that is in phase with the current supplied from the thermocouple to the electromagnet at the time of ignition, the operation of the extinguishing safety device is ensured.
In addition to increasing the speed, when overheating occurs, a reverse phase current is supplied to the electromagnet, thereby operating as a highly reliable overheat prevention stove.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure is a schematic diagram of the overheat prevention safety stove according to the present invention, in which 1 is a cooking container, 2 is a burner constituting a heating section, and 3 is a gas fire.

Reference numeral 4 indicates a thermocouple heated by a gas fire, and its output lead wire 5 constitutes the first excitation coil 7 of the IT electromagnet. 8 is a gas opening/closing cock, and the opening/closing valve 10 is closed by the repulsive force of a spring 9. 11 is a temperature sensor that detects the wall temperature of the cooking container, and control circuit 1
2 to the second excitation coil 13 of the electromagnet 6. 14 indicates 1tfi. 15 indicates a gas supply end. The first excitation coil 7 has a diameter of 0.5 to 0.5 mm.
The second excitation coil 13 had a configuration of about 10 turns made of copper wire with a diameter of about 0.1 mm, and the second excitation coil 13 had a configuration of about 300 turns made of a copper wire with a diameter of about 0.1 mm.

FIG. 2 shows a principle circuit diagram of the control circuit 12. R in FIG. 2 represents a resistance. 16 is a switch interlocked with the gas opening/closing cock 8, 17 and 18 are current limiting elements, and 19 is a capacitor. 11 indicates a bimetal as a temperature sensor.

In the above configuration, the operation will be described. At the same time as the gas opening/closing cock 8 is opened, the ignition is started and the switch 16 is turned on. A gas fire 3 ignites the burner 2 and gradually heats the thermocouple 4. On the other hand, Den a! A charging current flows from the capacitor 14 through the second excitation coil 13 to the capacitor 19 . At this time,
Due to the current limiting element 17, a constant current flows. Further, at this time, the current limiting element 18 is in an off state. That is, the third
A current flows as shown in the figure. A solid line 20 shows the charging current flowing through the second excitation coil from the power source 14. Once the capacitor 19 is charged, the charging current stops flowing.

A broken line 21 indicates the generated current from the thermocouple 4. As shown in the figure, immediately after ignition, until the thermocouple 4 is sufficiently heated, a charging current 2o of about 1 to 2 mA is applied to the on-off valve 10.
adsorbs. After that, about 50 to 10 (1
The generated current 21 of about wA attracts the on-off valve IO.

Therefore, when a power out state occurs and the generated current from the thermocouple 4 disappears, the on-off valve 10 closes.

When abnormal heating occurs, the switch of the bimetal 11 as a temperature sensor is turned off, and the current limiting element 17 is turned off.
is in the off state, and the current limiting element 18 is in the on state. The current charged in the capacitor 19 is transferred to the second excitation coil 13
through the ii:i limiting element 18. This situation is shown in FIG.
A discharge current 22 from the capacitor 19 flows in a phase opposite to the t current 21. Therefore, the opposite-phase attraction force due to the discharge current, ie, the detachment force, becomes greater than the attraction due to the electric current, and the on-off valve 10 is disengaged, gas is cut off, and the stove operates as an overheat prevention stove.

As explained above, according to the overheat prevention stove of the present invention, the extinguishing safety device operates quickly and there is no problem of ignition being difficult. Instead of turning on and off the generated power and low voltage and large current from the thermocouple using a temperature sensor, the large voltage and small current from the power supply 14 is turned on and off, resulting in highly reliable operation and highly safe overheating. Prevention stove can be realized.

In the above embodiments, a bimetal type temperature sensor is shown as the temperature sensor, but a ferrite type, liquid expansion type, or other type temperature sensor may be used. Furthermore, the temperature sensor may be composed of a thermistor, an infrared sensor, etc., and a switch function may be added in a separate circuit.As is clear from the above embodiments, according to the present invention, the ignition operation is A fast, highly reliable overheat prevention stove can be realized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of essential parts of an overheat prevention stove according to an embodiment of the present invention, FIG. 2 is a control circuit diagram thereof, and FIGS. 3 and 4 are characteristic diagrams illustrating the excitation current of the electromagnet. ■...Cooking container, 4...Thermocouple, 6.
...Electromagnet, 8...Opening/closing cock, 10.
... Safety valve, 11 ... Temperature sensor.

Claims (1)

[Claims] a heating section that heats the cooking container; an electromagnet that controls heating of the heating section; a thermocouple that is heated by the heating section and supplies current to the electromagnet; a temperature sensor that detects the temperature of the cooking container; Equipped with a power source that energizes the electromagnet,
An overheat prevention stove that controls current supply from the power source to the electromagnet by the temperature sensor.