JPS6126804Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a cooking device that uses a gas sensor to detect the amount of gas or moisture generated as the object is heated, and can automatically detect and control the cooking finish of the object.

An application has already been filed for a cooking device with a gas sensor, and as shown schematically in Fig. 1, the sensor part 1' is made of a sintered body mainly composed of _SnO2 , and a pair of electrodes are attached to the sensor part 1'. 2, 2 is supported on the surface of a ceramic pipe 3, and inside the ceramic pipe 3 is a heater 4 for heating the sensor section (hereinafter simply referred to as a gas sensor heater).
It is equipped with

In addition to this semiconductor type gas sensor, there are various types such as a catalytic combustion type using platinum, and the following explanation will deal with semiconductor gas sensors.

An example of the configuration of a cooking device with a gas sensor is shown in Fig. 2. According to this, an oven 6 serving as a cooking chamber is built into a cooking device main body 5, and food A placed on a tray 7 is cooked by a microwave oscillator 8 serving as a heat source for microwave cooking, an upper heater 9 and a lower heater 11 serving as heat sources for oven cooking, and a grill heater 10 serving as a heat source for grill cooking.
During cooking, carbon monoxide, carbon dioxide, water vapor, etc. generated by food A are contained in outside air blown from air outlet 14 by fan 13 driven by blower motor 12, and are exhausted to the outside of oven 6 through exhaust outlet 15. After coming into contact with gas sensor 1, they are exhausted from exhaust outlet 16 of main body 5.

The amount of gas or water vapor generated by food A (in other words, the exhaust gas concentration or exhaust humidity) tends to increase as cooking progresses. It has the property of decreasing as it increases.

Therefore, the heating status of food A can be indirectly detected using an electric circuit by converting the change in resistance value of gas sensor 1 into a change in voltage. The operations of the heater 11, grill heater 10, etc. can be automatically controlled.

By the way, when cooking in an oven, the upper heater 9 and lower heater 11 disposed at the top and bottom of the oven 6 generate heat, for example, in an atmosphere where the temperature inside the oven is 250°C.
Food A is heated for 30 minutes, so the location where gas sensor 1 is installed is also exposed to a high temperature of 200°C. Therefore, in such a high-temperature environment, it is necessary to use a heater for the gas sensor.
If the sensor section 1' of the gas sensor 1 were to be energized and generated to generate heat, the sensor section 1' of the gas sensor 1 would be exposed to higher temperatures, leading to deterioration of the performance and life of the gas sensor itself. In addition, the heater for the gas sensor is approximately
Heated to 500℃.

Furthermore, since oven cooking involves setting the ambient temperature inside the oven to a certain value and finishing the cooking after a predetermined period of time has elapsed, indirect detection by a gas sensor is not necessary.

Furthermore, when grilling, the cooking time is sometimes set using a timer, but if the cooking time is set much longer than specified, the environmental temperature of the gas sensor may exceed 150°C. There is also.

In view of the above, in a cooking device equipped with a gas sensor, when the temperature near the gas sensor exceeds a predetermined value (for example, 150° C.), it is desirable to immediately cut off the power supply to the gas sensor heater.

The present invention has been devised in view of these points, and will be described in detail below, including FIG. 3.

FIG. 3 is an electric circuit diagram assembled in the cooker shown in FIG. A door switch 1 that opens and closes in conjunction with a door that can open and close the opening of the door.
7. The AC is activated through the following switches: a cook switch 18 that starts cooking, a selector switch 19 that selectively switches between microwave cooking, oven cooking, and grill cooking functions, and a relay switch 21 that is parallel to the timer switch 20. Connected to 100V AC power supply. Timer switch 2 above
0 is driven to open and close by a timer 22, and the relay switch 21 is driven to open and close by a relay 24 connected in series to the collector emitter of a transistor 23.

Reference numeral 25 denotes a transformer constituting a DC power source, whose primary winding is connected to an AC power source via a door switch 17 and a cook switch 18, and a rectifying diode 26 is connected to its secondary winding. On the output side of the rectifier circuit 36 consisting of the transformer 25 and the diode 26, a series circuit of the resistor 27 and the sensor section 1' of the gas sensor 1, a series circuit of the resistor 28 and the resistor 29, and a series circuit of the transistor 23 and the relay 24 are connected. Connected. The connection point between the resistor 27 and the sensor section 1' and the connection point between the resistor 28 and the resistor 29 are connected to the input terminal of the comparator 30, respectively.

Here, the connection point 3 between the resistor 27 and the sensor section 1'
While the voltage of 1 decreases as the amount of gas or water vapor that comes into contact with gas sensor 1 increases,
The voltage at the connection point 32 between the resistors 28 and 29 is set and maintained at a predetermined voltage depending on the resistance value. Therefore, the voltage at the connection point 31 is input to the comparator 30 as a voltage to be compared, and the voltage at the connection point 32 is input as a reference voltage for determining the cooking completion time. Therefore, when the cooking is finished, both voltages match, and at that time, the output of the comparator 30 is inverted, the transistor 23 whose base is connected to the output terminal is switched to a non-conducting state, and the relay 2
4 and opens the relay switch 21 to stop the operation of the heat source.

Further, the gas sensor heater 4 is connected to an AC power source via a thermostat 34 and a resistor 35 installed near the gas sensor 1.

In the cooking device constructed as described above, when microwave cooking or grill cooking is selected as the cooking function and the changeover switch 19 is set to the a-contact or the b-contact, the microwave oscillator 8 or the grill heater 10 is selected as the heat source, and the gas sensor heater 4 is maintained in a powered state via the normally closed thermostat 34. In this state, food A is placed on the tray 7 of the oven 6, the door is closed, and the cooker switch 1 is turned on.
When the switch 8 is closed, cooking is started by the selected heat source. When the resistance value of the sensor portion 1' of the gas sensor 1 reaches a value corresponding to the gas concentration or humidity, which indicates the desired cooking finish, the two input voltages of the comparator 30 become equal. As a result, the output of the comparator 30 is inverted, so the relay switch 21 opens and cooking is automatically terminated.

On the other hand, when the changeover switch 19 is set to the c contact and oven cooking is selected as the cooking function, the desired oven internal temperature is set in advance by an oven internal temperature setting means (not shown).
Set the cooking time on the timer 22. Therefore, the timer switch 20 is kept closed during the set cooking time, and the upper heater 9 and lower heater 11
An energizing path is formed, and the timer switch 20 is opened.
Cooking ends when the food is cooked.

In the case of oven cooking, the temperature near the gas sensor 1 exceeds 150° C., so the thermostat 34 is opened and the electricity to the gas sensor heater 4 is immediately cut off.

Furthermore, when grilling is performed for the cooking time set in the timer 22, if the setting is incorrect and grilling is performed for a long time, the temperature near the gas sensor 1 may rise to 150°C as described above.
Although the temperature may exceed 0.degree. C., the thermostat 34 automatically opens and the power supply to the gas sensor heater 4 is immediately cut off.

According to the cooking device with a gas sensor of the present invention, which is constructed as described above, when the ambient temperature of the gas sensor exceeds a predetermined value, the power supply to the gas sensor heater is automatically cut off, and the sensor part is heated to an unnecessary high temperature. It is not exposed to the environment and its performance and lifespan are maintained.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining a gas sensor, and a
The figure is an equivalent circuit, and b is a schematic configuration diagram. FIG. 2 is a schematic configuration diagram of a cooking device equipped with a gas sensor. FIG. 3 is an electric circuit diagram assembled in a cooking device according to an embodiment of the present invention. 1...Gas sensor, 1'...Sensor section, 4
... Gas sensor heater, 8 ... Microwave oscillator, 9 ... Upper heater, 10 ... Grill heater, 11 ... Lower heater, 19 ... Selector switch,
34...Thermostat. 〓〓〓〓

Claims (1)

[Scope of Claim for Utility Model Registration] In a cooking device in which the heating status of an object to be heated is detected by a gas sensor, a thermostat is provided near the gas sensor,
A cooking device equipped with a circuit that cuts off power to a heater built into a gas sensor when the temperature near the gas sensor exceeds a predetermined temperature.