JPS587138B2 - High frequency heating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-frequency heating device for heating an object using radio wave energy, and more particularly to a means for controlling the heating of an object to be heated by the device.

It is well known that radio energy in the microwave band is used to heat objects.

A common configuration of such high-frequency heating devices is a configuration in which radio waves emitted from a radio wave generation source such as a magnetron are supplied directly or through a waveguide to the inside of a cavity called an oven in which the object to be heated is housed. belongs to.

In the apparatus having such a configuration, the heating time of the object to be heated is usually controlled by a timer such as a timer.

In this case, it is necessary to adjust the heating time appropriately depending on the type of the object to be heated, that is, the difference in dielectric loss coefficient, the weight, and the initial temperature, that is, the temperature of the object before heating.

If the time adjustment is inappropriate, the result will be that the object to be heated is under-heated or over-heated.

Conventionally, the solution to this problem was to insert a temperature sensing element into the object to be heated, directly detect the temperature of the object, and control the oscillation of the magnetron to control the heating of the object. methods are being used.

In the device having such a means, the object to be heated loses its shape,
This may cause damage by interfering with cooking.

SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide a means for controlling the heating of an object to be heated, regardless of the type, weight, or initial temperature of the object, and which does not cause the object to lose its shape.

More specifically, it is desired to detect a physical change in the air flow passing through the cavity and control a radio wave generation source using the signal to control the heating of the object to be heated, and to reliably configure such a means. There is an aim of the present invention.

Examples will be described below with reference to the accompanying drawings.

In FIG. 1, 1 is the main body of the device, and 2 is a door attached to the main body 1 so as to be openable and closable.

The main body 1 has a cavity 3 as shown in FIG. 2, and a door 2 is disposed to close an entrance/exit (not shown) of the cavity 3 for the object to be heated.

In FIG. 2, 4 is a magnetron which is a radio wave generation source.

5 is a blower for cooling the magnetron 4; the blower 5 communicates with what is called an air guide A6, and the air guide A6 communicates with the magnetron 4.

7 is an air guide B for exhausting the wind that cools the magnetron 4, and 8 is an antenna force bar that surrounds the antenna section of the magnetron 4.

The antenna cover 8 is made of a dielectric material with low loss at high frequencies.

Reference numeral 9 denotes a rotating saucer, on which a heated object 12 is placed, a rotating saucer drive motor 10 is used as a drive source, and a coupling piece 11 transmits the driving force of the rotating saucer drive motor 10. Thus, the rotary tray 9 is configured to perform rotational movement.

13 is an intake duct, and 14 is an intake opening formed in the cavity 3.

The wind entering the cavity 3 is introduced into the cavity 3 via the intake duct 13 and through the intake opening 14 .

15 is an exhaust opening formed in the cavity 3, and 16 is an exhaust duct.

The wind exiting the cavity 3 passes through an exhaust opening 15 and is exhausted through an exhaust duct 16. One end of the exhaust duct 16 is disposed near the intake port 17 of a motor fan 19, and the intake force of the motor fan 19 is transferred to the exhaust duct. 16. Reference numeral 18 denotes a detection element for detecting physical changes in the wind, that is, airflow, and in this embodiment, an element such as a thermistor that is sensitive to temperature changes in the airflow is used.

20 is an amplification means for amplifying the signal of the detection element 18;
20 is operated by the output generated from the amplifying means 21;
This is a control means for controlling the oscillation of the magnetron 4.

Reference numeral 22 denotes an air guide C for discharging the airflow generated by the motor fan 19 to the outside, and the air guide C 22 and the air guide B7 are disposed adjacent to each other.
Moreover, it is partitioned by the partition piece 23 so that the airflows of the other parties do not merge inside the main body 1.

24 is an on-off valve, and 25 is a communication port bored in the cavity 3.

Reference numeral 26 denotes a drive source for the on-off valve, and when the drive source 26 operates, the on-off valve 24 opens and the airflow generated by the blower 5 flows into the cavity 3, passing through the detection element 18 and creating a path for the airflow generated by the motor fan 19. is emitted to the outside of the main body 1 through.

Reference numeral 27 denotes a timer, and the timer 27 operates the drive source 26 for a predetermined time based on the signal from the amplification stage 20.

Next, the operation of the above embodiment and the effects of each part will be explained.

Radio waves generated by the magnetron 4 are radiated into the cavity 3 and heat the object 12 to be heated.

The object to be heated 12 rotates together with the rotating tray 9 and is uniformly heated.

As the heating of the object to be heated 12 progresses, the radiant heat radiated from the object to be heated 12 increases.

This heat is transferred to the sensing element 18 by the wind passing through the cavity 3.

The sensing element 18 generates a signal in response to changes in the radiant heat of the object 12 to be heated.

The signal generated from the sensing element 18 is amplified by the amplification stage 20 and transmitted to the control stage 21.

Therefore, when the object to be heated reaches a desired temperature, the control means 21 is activated, the oscillation of the magnetron 4 is controlled, and the heating of the object to be heated is controlled.

The present embodiment operates as described above.

Incidentally, the first feature of this embodiment is that the heating of the object to be heated is not controlled by a timer.

Therefore, since it is not necessary to adjust the heating time, it becomes possible to control heating of the object to be heated to a desired temperature regardless of the type, weight, or initial temperature of the object to be heated.

The second feature is that it is a so-called indirect detection method that detects temperature changes of the heated object without directly inserting the sensing element 18 into the heated object, so the heated object does not lose its shape. be.

The third characteristic is the uniqueness of the wind path.

That is, as described above, the airflow that passes through the cavity 3 and the airflow that cools the magnetron 4 are provided independently, and if necessary, the airflow that has cooled the magnetron 4 is introduced into the cavity 3 to detect the detection element. It is now possible to connect to the 18th section.

The airflow passing through the cavity needs to be a cold field in which outside air is directly introduced so as not to cause disturbance to the sensing element 18.

Therefore, water vapor generated from the object to be heated 12 condenses in the airflow path, and a large amount of water droplets accumulate near the sensing element 18 portion.

These water droplets not only significantly reduce the durability of the sensing element 18, but also disturb the sensing performance.

Water droplets adhering to the sensing element 18 slow down the response of the sensing element 18.

Further, the water droplets adhering to the vicinity of the sensing element 18 absorb the heat of vaporization from the airflow, and disturb the correspondence between the progress of heating the object to be heated 12 and the physical change in the airflow.

However, in the present invention, the heating of the object to be heated 12 is controlled by the operation of the sensing element 18, and the sensing element 18
Since the water droplets can be swept away through the warm airflow after cooling the magnetron 4 while the heating control using the magnetron 4 is suspended, the above problem can be solved.

Here, the reason why the airflow is swept out during the rest period is that the airflow after the magnetron has been cooled itself causes disturbance to the detection element.

Therefore, when the sensing element 18 is controlling the heating of the object to be heated, it is preferable that the airflow after being cooled by the magnetron is not introduced from the cavity into the sensing element 18 portion.

Furthermore, even during the suspension period, if the airflow after cooling the magnetron is introduced into the sensing element part more than necessary, heat will accumulate in the sensing element 18 and its surroundings, creating a disturbance condition. It is preferable to introduce time-based magnetron cooling air into the sensing element section.

As described above, according to the present invention, it is possible to control the heating of an object to be heated without causing the object to be heated to deform, regardless of the type of the object to be heated, its initial weight or initial temperature, and the means for doing so can be reliably configured. A high frequency heating device can be provided.

In addition, in the embodiment, a configuration was presented in which the oscillation of the magnetron is controlled by capturing the temperature change of the airflow passing through the cavity, but the configuration is not necessarily limited to such a configuration.
For example, the idea of the present invention can also be applied to a structure in which the heating of the object to be heated is controlled by controlling the oscillation of a magnetron using other physical changes such as changes in the humidity of airflow due to water vapor generated from the object to be heated. Needless to say, it can be done.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a high-frequency heating device according to the present invention,
FIG. 2 is a schematic cross-sectional view of the main part. 3...Cavity, 4...Magnetron, 5
...Blower, 14...Intake opening, 1
5...Exhaust opening, 18...Detection element, 19...Motor fan, 24...Opening/closing valve, 25...Communication port , 26... Drive source, 21... Timing means.

Claims (1)

[Claims] 1. A cavity 3 for storing an object to be heated, an opening through which air flows, and a physical change in the air flow near the outlet of the opening. It also includes a detection element 18 that detects the air flow path through the cavity 3 and the magnetron 4.
A high-frequency heating device characterized in that an airflow path for cooling the magnetron 4 is independently provided, and the airflow for cooling the magnetron 4 is introduced into the cavity 3 by a switching means. 2 In claim 1, the switching means has a cavity 3.
This high-frequency heating device is characterized by using an on-off valve 24 that opens and closes a communication port 25 provided in the . 3. The high-frequency heating device according to claim 1, characterized in that the switching means is a switching means operated by a signal from the detection element 18. 4. The high-frequency heating device according to claim 1, characterized in that the switching means is a switching means that operates for a certain period of time by a timer. 5. The high-frequency heating device according to claim 1, characterized in that the switching means is a switching means that is activated for a certain period of time by a timer that is activated by a signal from the detection element 18.