JPH0560329A - Heating heater - Google Patents

Abstract

PURPOSE:To obtain a microwave oven in which the absolute humidity in a heating compartment can be accurately, properly detected by an absolute humidity sensor based on steam contained in the atmospheric gas in the heating compartment that flows along an exhaust duct. CONSTITUTION:An exhaust duct 7 is attached on the upper wall of a heating compartment where food is heated, and the atmospheric gas in the heating compartment is discharged through the exhaust duct 7. The exhaust duct 7 has an opening 9 and a protruding part 10 that is partly formed near the opening 9 and projected outside time exhaust duel 7. An absolute humidity sensor 11 has a flange 12 and the flange 12 is attached on the protruding part 10 so that the absolute humidity sensor 11 is accommodated in the exhaust duct 7 through the opening 9. The absolute humidity sensor 11 detects the absolute humidity of the atmospheric gas flowing along the exhaust duct 7 and outputs control signals for controlling a halogen heater, etc. A heat-insulating sheet material 21 is provided between the flange 12 of the absolute humidity sensor 11 and a brim 20 of the opening 9 of the exhaust duct 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device for a microwave oven or the like, in which information on the atmosphere of a heating chamber flowing in an exhaust duct is detected by a sensor to control heating.

[0002]

2. Description of the Related Art Recently, a microwave oven which uses a sensor for detecting absolute humidity in a heating chamber and performs microwave heating or heater heating based on the output of the sensor has been put into practical use (Japanese Patent Publication No. 2-46101). ). Specifically, the sensor is fixed to an exhaust duct that exhausts the atmosphere in the heating chamber, and detects the absolute humidity, which is information on the atmosphere in the heating chamber flowing in the exhaust duct.

However, in such a structure,
High heat accompanying heating is transmitted from the heating chamber side to the sensor via the discharge duct, and the detection accuracy of the sensor is reduced.

[0004]

SUMMARY OF THE INVENTION According to the present invention, a sensor fixed to the duct detects information about the atmosphere in the heating chamber flowing in the discharge duct, and the detection accuracy of this sensor is affected by high heat accompanying heating. Therefore, it is intended to provide a heating device which can prevent heating from being lowered and which can properly control heating based on the sensor output.

[0005]

The heating device of the present invention comprises a heating chamber for containing an object to be heated, a heating means for heating the object to be heated in the heating chamber, and a heating chamber connected to the wall of the heating chamber. The exhaust duct for exhausting the atmosphere of, the opening formed in the exhaust duct, the convex portion partially formed in the exhaust duct in the vicinity of the opening so as to project outward, and the flange portion. A sensor that enters the discharge duct from the opening in a state where the flange portion is fixed to the convex portion, detects information of an atmosphere flowing in the discharge duct, and outputs a signal for controlling the heating means, The heat insulating seal member is interposed between the collar portion of the sensor and the peripheral edge portion of the opening of the discharge duct. Further, it has a mitigating means mounted in the exhaust duct to mitigate the flow of the atmosphere to the sensor.

[0006]

[Function] The sensor is mounted by fixing the flange to the partial convex part of the exhaust duct, and although high heat due to heating is transmitted from the heating chamber side to the exhaust duct, it is difficult to reach the above sensor, and the detection accuracy of the sensor is high. Does not fall under the influence of high heat.

Further, when the collar portion of the sensor is fixed to the partial convex portion in this way, the collar portion is formed on the discharge duct so that the sensor enters the discharge duct when the sensor is attached except the convex portion. Away from the peripheral edge of the opening. Then, as it is, the atmosphere inside the heating chamber flowing in the exhaust duct becomes
The sensor leaks out of the discharge duct through the opening to the outside of the exhaust duct, and the sensor cannot correctly detect the atmosphere information. However, the above-mentioned separated part is covered with a heat insulating sealing material,
The atmosphere is suppressed from leaking out of the exhaust duct, and the sensor detects correct atmosphere information.

Further, in the discharge duct, the mitigating means mitigates the flow of the atmosphere with respect to the sensor, and in this respect also, the deterioration of the detection accuracy of the sensor is suppressed.

[0009]

1 to 3 show the overall structure of a microwave oven according to an embodiment of the present invention. A heating chamber 1 for accommodating food is provided in the main body of the microwave oven. The food in the heating chamber is microwave-heated by a microwave from a magnetron 2 which is a heating means and a halogen heater 3 which is another heating means. Is heated by the heater. Halogen heater 3
Is located above the heating chamber upper wall 4, but the heating chamber upper wall 4
A large number of punching holes are formed in the portion directly below the heater, and the heater heat is supplied from the punching holes into the heating chamber to heat the food with the heater. The upper half of the halogen heater 3 is covered with a metallic reflector 5 for efficiently supplying the heater heat into the heating chamber. Furthermore,
A cooling fan 6 for cooling the magnetron 2 is provided, and the cooling air after cooling the magnetron is supplied into the heating chamber 1 and reaches the reflecting plate 5 along with the atmosphere in the heating chamber, and the heating chamber upper wall. 4 is discharged to the outside through a metal discharge duct 7 connected to the reflector 4 via a reflection plate 5.

4 and 5 show the detailed structure of the exhaust duct 7 portion. An opening 9 is formed in the upper wall 8 of the exhaust duct 7, and the exhaust duct 7 near the opening is partially formed with a pair of convex portions 10 protruding outward. And
An absolute humidity sensor 11 is inserted into the discharge duct 7 through the opening 9, and the absolute humidity sensor 11 is fixed to the convex portion 10 with a screw 13 through a flange portion 12. In such a fixed state, the absolute humidity sensor 11 detects the information of the atmosphere in the heating chamber passing through the exhaust duct 7, specifically the absolute humidity, and outputs a signal for controlling the magnetron 2 and the halogen heater 3. When the sensor 11 is fixed to the partial convex portion 10 via the flange portion 12 in this manner, high heat (especially when the heater is heated) accompanying heating is transmitted from the heating chamber 1 side to the exhaust duct 7, but is also transmitted to the sensor 11. It is difficult, and the detection accuracy of the sensor 11 is not affected by high heat so much that it does not decrease.

This point will be described in a little more detail with reference to FIG. 6 showing an absolute humidity output circuit including the absolute humidity sensor 11. The absolute humidity sensor 11 is composed of open-type and closed-type temperature detecting thermistors 14 and 15 having the same temperature characteristics, and the absolute humidity output circuit includes these thermistors 14 and 1.
A series circuit in which 5 are connected in series and the first and second resistors 16,
It is composed of a bridge circuit 18 in which series circuits in which 17 are connected in series are connected in parallel, and an amplifier 19 which inputs a level difference between the midpoints of both series circuits and outputs absolute humidity. In this absolute humidity output circuit, if the atmosphere flowing in the exhaust duct 7 does not contain water vapor, the thermistors 14 and 15 of the absolute humidity sensor 11 only change uniformly based on the ambient temperature. No level difference occurs between the midpoints of both series circuits of the bridge circuit 18, and the absolute humidity output of the amplifier 19 becomes zero. On the other hand, when the food is heated to generate steam from the food and the steam flowing in the exhaust duct 7 contains the steam, the thermistors 14 and 15 are generated.
Among them, the closed type thermistor 15 is not affected by water vapor, but the open type thermistor 14 has water vapor adhering to the surface and its resistance value changes due to its vaporization heat.
A level difference occurs between the midpoints of both series circuits of 8 and the amplifier 19
Outputs the absolute humidity according to the water vapor.

Considering such an absolute humidity output circuit, although the thermistors 14 and 15 are selected to have the same temperature characteristics, it is said that the temperature characteristics of the thermistors 14 and 15 are completely the same. No, each thermistor 1
There are some differences in the thermal response speed and temperature coefficient of Nos. 4 and 15.
Then, even if the high heat is transmitted to the absolute humidity sensor 11, a considerable level difference occurs between the midpoints of both series circuits of the bridge circuit 18, which causes a decrease in sensor detection accuracy due to the influence of the high heat. However, if the high heat is not easily transmitted to the absolute humidity sensor 11 as described above, the sensor 11 is not significantly affected by the high heat and the sensor detection accuracy does not decrease.

Returning to FIGS. 4 and 5, in the structure in which the absolute humidity sensor 11 is fixed to the partial convex portion 10 via the collar portion 12, the collar portion 12 other than the convex portion 10 is The peripheral portion 2 of the opening 9 formed in the discharge duct 7 so that the sensor 11 enters the discharge duct 7 when the sensor 11 is mounted.
Separate from 0. Then, as it is, the exhaust duct 7
The atmosphere in the heating chamber flowing inside leaks out of the discharge duct through the opening 9 to the outside of the discharge duct, and the sensor 11 cannot correctly detect the atmosphere information. In view of this, the collar portion 12
A heat insulating seal material 21 is interposed between the heat insulating seal material 21 and the opening peripheral edge portion 20, and the separated portion is covered with the heat insulating seal material 21, so that the atmosphere is prevented from leaking to the outside of the discharge duct 7, and the sensor 1
1 detects the correct absolute humidity.

Further, in the discharge duct 7, a ring-shaped relaxation body 22 which is located around the absolute humidity sensor 11 and moderates the flow of the atmosphere to the sensor 11 is welded and fixed to the discharge duct 7. With this relaxing body 22,
The fast-flowing atmosphere does not hit the sensor 11 locally, and the atmosphere relaxed by the relaxing body 22 reaches the sensor 11 from the opening 23 of the relaxing body 22, which also lowers the detection accuracy of the sensor 11. Suppressed. Incidentally, when the atmosphere locally hits the sensor 11, a level difference occurs between the midpoints of both series circuits of the bridge circuit 18 at this time as well, and the detection accuracy of the sensor 11 deteriorates.

[0015]

According to the present invention, in the structure in which the information of the atmosphere in the heating chamber flowing in the discharge duct is detected by the sensor fixed to this duct, the detection accuracy of this sensor is affected by the high heat accompanying the heating. It is possible to provide a heating device that can suppress the decrease in temperature, can detect the correct atmosphere information by the sensor, and can perform the heating control correctly based on the sensor output.

[Brief description of drawings]

FIG. 1 is a perspective view of a microwave oven according to an embodiment of the present invention.

FIG. 2 is a side sectional view of the microwave oven.

FIG. 3 is a plan sectional view of the microwave oven.

FIG. 4 is a cross-sectional view of main parts of the microwave oven.

FIG. 5 is a plan view of a main part of the microwave oven.

FIG. 6 is an absolute humidity output circuit diagram of the microwave oven.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating chamber 2 Magnetron 3 Halogen heater 7 Exhaust duct 9 Opening 10 Convex part 11 Absolute humidity sensor 12 Collar part 21 Insulating sealing material 22 Relaxing body

Claims (2)

[Claims] 1. A heating chamber for containing an object to be heated, a heating means for heating the object to be heated in the heating chamber, and an exhaust duct connected to a wall of the heating chamber for exhausting an atmosphere in the heating chamber.
An opening formed in the discharge duct, a convex portion partially formed on the discharge duct in the vicinity of the opening so as to project outward, and a flange portion, and the flange portion is fixed to the convex portion. A sensor that enters the exhaust duct from the opening in the above state, detects information on the atmosphere flowing in the exhaust duct, and outputs a signal for controlling the heating means, and a collar portion of the sensor and the exhaust duct. A heating device comprising a heat insulating sealing material interposed between the heat insulating sealing material and the peripheral edge of the opening. 2. The heating device according to claim 1, further comprising: a relaxation unit that is mounted in the exhaust duct to reduce a flow of an atmosphere with respect to the sensor.