JP2554204B2 - microwave - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to improvements in microwave ovens.

[0002]

2. Description of the Related Art Generally, in a microwave oven, there is no food (that is, operation is performed only with turntables, operation in such a state is referred to as no-load operation), and there is also a turntable in an oven. Not totally empty
(Hereinafter, this completely empty operation is referred to as complete no-load operation). In that case, a part of the turntable may be locally heated, or the door glass may be locally heated. To prevent that,
The position of the portion where the microwave is radiated into the oven chamber (hereinafter referred to as iris) is set to a position where the microwave is evenly distributed in the oven chamber.

[0003]

As described above, the position of the iris must be set so that the microwaves are evenly distributed in the oven in preparation for the unloaded operation state and the completely unloaded operation state. . However, conventionally, the examination of the installation location of the iris has been carried out by trial and error, so that there is a problem that it takes a very long time. Even if the mounting position of the iris is carefully set, it is not possible to completely prevent local heating of the turntable and door glass in the no-load operation state or the completely no-load operation state, and change the material of the turntable, etc. There is also a problem that the cost is increased due to the necessity of such things.

Therefore, an object of the present invention is to make it possible to easily set the installation location of the iris and to prevent the interior of the oven from being locally heated above a predetermined temperature even during no-load operation or completely no-load operation. To provide a range.

[0005]

In order to achieve the above object, the microwave oven of the present invention is a reset type that performs a heating off operation when the temperature inside the oven reaches a predetermined temperature higher than the optimum heating temperature of the object to be heated. A dummy object to be heated having a lower dielectric loss than that of the object to be heated is attached to the side wall of the oven by projecting one end of the one not provided with the resettable temperature fuse into the oven chamber. The heater heating and the microwave heating are stopped when the resettable thermal fuse operates.

[0006]

The heating operation is started by heater heating or microwave heating in a no-load operation state in which there is no object to be heated in the oven chamber or in a completely no-load operation in which there is nothing in the oven chamber. At this time, since there is no object to be heated in the oven chamber, the dummy object to be heated attached to the side wall with one end protruding into the oven chamber is heated first. In this way, the temperature of the dummy heated object reaches the predetermined temperature set higher than the optimum heating temperature of the heated object. Then, the resettable temperature fuse provided in the dummy object to be heated carries out the heating-off operation to stop the heater heating and the microwave heating. As a result, if the above-mentioned predetermined temperature is set below the temperature at which the turntable and door glass are damaged by heat, the turntable and door glass may be locally heated and damaged due to no-load operation or complete no-load operation. Absent. On the other hand, when there is an object to be heated such as food in the oven chamber, the object to be heated has a higher dielectric loss than the dummy object to be heated, so that the object to be heated is heated first. As a result, in the case of normal heating, since the object to be heated is heated to the optimum temperature before the dummy object to be heated reaches the predetermined temperature, the resettable temperature is set before the optimum heating of the object to be heated is completed. The fuse does not work.

[0007]

The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 is a view showing the inside of the oven of the microwave oven of the present invention. The dummy insulator 3 having a rectangular parallelepiped shape is attached to the side wall 2 of the oven 1 so that the tip of the oven protrudes into the oven chamber. Further, as shown in FIG. 2, the dummy insulator 3 is used.
The portion outside the side wall 2 of the reset type thermal fuse (hereinafter referred to as a thermo-cut type) in which the heating-off operation temperature is set to a temperature at which the operation should be forcibly stopped in the case of the above-described no-load operation or complete no-load operation. Say 4) The heating-off operation temperature of the thermocut is set to a temperature which is higher than or equal to the optimum heating temperature of the object to be heated such as food and does not cause thermal deformation of the turntable, door glass and the like. Further, the return temperature is set to room temperature (about 20 degrees Celsius to 25 degrees Celsius).

FIG. 3 is a schematic view of a heating circuit in a microwave oven in which the dummy insulator 3 is attached to the side wall 2 as described above. This circuit diagram simplifies and expresses only the part related to heater driving and magnetron driving. Electricity from the outlet 10 is supplied to the convection heater 5, the grill heater 6, the grill heater 7 and the power transformer 8 for driving the magnetron 9 through the thermo cut 4 attached to the dummy insulator 3. At that time, switch 1
A combination of heating means can be selected by switching 1 and 12 as needed. In the microwave oven having the above-mentioned configuration, when the no-load operation state or the completely no-load operation state is entered, the dummy insulator 3 is the earliest in the oven because the volume of the dummy insulator 3 is smaller than that of the turntable or door glass. It is red-hot at a high temperature. Therefore, the temperature of the dummy insulator 3 reaches the above-mentioned heat-off operation temperature before the turntable in the oven chamber, the door glass, and the like are locally heated to a high temperature that causes thermal deformation. Then, the thermocut 4 attached to the dummy insulator 3 performs the heating off operation, and the convection heater 5, the grill heater 6, the grill heater 7, and the power transformer 8 are performed.
Stop supplying electricity to. Therefore, before entering the no-load operation state or the completely no-load state and causing the thermal deformation of the turntable or door glass, the thermocut 4 stops the heating of the inside of the oven to prevent the turntable or door glass from being heated. This prevents local heating and the resulting damage to the turntable and the like.

On the other hand, when there is even a small amount of food such as food in the oven chamber, the object to be heated has a higher dielectric loss than the dummy insulator 3 and therefore the object to be heated is optimally heated first. Reach the temperature. Therefore, when the temperature of the object to be heated reaches the optimum heating temperature, the dummy insulator 3 has not yet reached the temperature at which the thermocut 4 is turned off. That is, in the case of normal heating where there is an object to be heated in the oven chamber, the thermocut 4 does not perform the heating off operation, and the object to be heated can be reliably heated to the optimum temperature.

In the above embodiment, the dummy insulator 3 is attached to the side wall 2 of the oven 1, and the dummy insulator 3 is provided with the thermocut 4 therein. However, what is provided with the thermocut 4 in the present invention is not limited to the insulator, and the dielectric loss is lower than that of the object to be heated such as food, and the dielectric loss is appropriate to the extent that microwave heating is performed to some extent. Any substance can be used.

[0011]

As is apparent from the above, the microwave oven of the present invention is provided with a resettable temperature fuse whose heating-off operation temperature is set to a predetermined temperature higher than the optimum heating temperature of the object to be heated, and the above-mentioned object to be heated. A dummy object to be heated having a lower dielectric loss than that of the object is attached to the side wall of the oven so that one end of the object to be heated projects into the oven chamber. Therefore, if the heat-off operation temperature of the resettable thermal fuse is set to a temperature lower than the temperature at which the turntable and door glass are damaged by heat locally, it will be possible to operate in a no-load operation state or a completely no-load operation state. Before the turntable and door glass are damaged by local heating, the reset type thermal fuse of the dummy heated object performs the heating off operation,
It is possible to prevent damage to the door glass and turntable due to local heating. That is, according to the present embodiment, regardless of the installation location of the iris, the turntable and the door glass are not locally heated during no-load heating or completely no-load heating, and thermal damage can be prevented. Therefore, you can easily set the iris setting point in a short time,
It is not necessary to change the material of the turntable, etc. to a heat resistant material, and it is possible to prevent cost increase.

[Brief description of drawings]

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

FIG. 2 is a mounting view of a thermocut on a dummy insulator.

FIG. 3 is a schematic diagram of a heating circuit.

[Explanation of symbols]

1 ... Oven, 2 ... Side wall, 3 ... Dummy insulator, 4 ... Thermo cut, 5 ... Convection heater, 6, 7 ... Grill heater, 8 ... Power transformer, 9 ... Magnetron.

Claims (1)

(57) [Claims] 1. A dummy heated object having a dielectric loss lower than that of the object to be heated and provided with a resettable temperature fuse for performing a heating-off operation when the temperature inside the oven reaches a predetermined temperature higher than the optimum heating temperature of the object to be heated. When the resettable temperature fuse operates, the object is attached to the side wall of the oven by projecting one end of the one not provided with the resettable temperature fuse into the oven, and heating the heater and microwaves. A microwave oven characterized in that it is adapted to stop.