JP2962074B2 - High frequency heating equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting bracket for a magnetron overheating protection device of a high frequency heating device, and more particularly to a shape and a mounting position.

[0002]

2. Description of the Related Art In recent years, the food service industry has been required to devise ways to increase profits by saving as many people and spaces as possible.
Under such circumstances, high-frequency heating devices for heating and cooking foods are also required to be small and have high output. As one device for realizing this with low cost and high reliability, there is a device using two or more magnetrons of a household high-frequency heating device which has been proven in mass production. When two or more magnetrons are used, the magnetron is cooled by two or more cooling fans. However, in this case, the magnetron overheating protection device does not work when the cooling fan stops due to a failure of the cooling fan. There are things. This is because two or more cooling fans are used. However, even if one cooling fan is stopped, the other cooling fans are running and the high frequency is higher than the magnetron exhaust port on the stopped side. This is because a phenomenon occurs in which the external cold air flows backward into the heating device. Due to this phenomenon, the higher temperature part of the magnetron cooling air passage near the exhaust opening and the part near the cooling fan reverses depending on whether the cooling fan has stopped due to a failure or is rotating in the normal state. . Therefore, the mounting position of the overheating protection device is selected near the exhaust opening of the magnetron, and the operating temperature of the overheating protection device is detected so as to detect when the temperature rises abnormally due to the failure of the magnetron itself while the cooling fan is rotating. Is set, the detection when the cooling fan is stopped cannot be performed because the temperature is lowered by the cool air from the exhaust opening of the magnetron. Also, in order to cope with the above point, if the overheating protection device is selected near the cooling fan and the operating temperature is set to work when the cooling fan stops, the magnetron breaks down while the cooling fan is rotating. The temperature cannot be detected sufficiently by the cooling air from the cooling fan and the temperature cannot be increased.

A conventional example will be described below with reference to FIGS. 3 to 8. FIG. Conventionally, this type of high-frequency heating apparatus has two magnetrons 2 in a heating chamber 1 as shown in FIGS.
a to the waveguide 3
a or waveguide 3b. The cooling of the two magnetrons is performed by cooling fans 4a and 4b, respectively, and the flow of the cooling air flows through the intake openings 7.
Enters the high-frequency heating device as cooling air 9 from the cooling air 9
a, the cooling air 9b is used to cool the magnetron 2a and the magnetron 2b.
a, it is discharged from the exhaust opening 8b.

As means for protecting the magnetron from abnormal overheating, the overheating protection devices 10a and 10b are directly attached to the magnetron. Next, the operation circuit will be described with reference to FIG. This circuit consists of two typical high frequency heating circuits in parallel.
Are connected. From the secondary circuit of the high voltage transformer 12a or the high voltage transformer 12b, the magnetron 2a,
A heating chamber 1 is provided in a primary circuit of the high-voltage transformer 12a and the high-voltage transformer 12b for supplying power to the magnetron 2b.
A switch 14a which is turned on and off in response to a signal from a switch 13a, a switch 13b or an electronic circuit 16 interlocked with the door
a, a relay 14b, and these switches and relays are used to connect one of the high-voltage transformers 12a and 12b.
The next side is cut off and the corresponding magnetrons 2a and 2b stop oscillating. When the relays 4a and 4b stop, the corresponding cooling fans 4a and 4b also stop. The electronic circuit 16 is a low-voltage transformer 1
5, the overheating protection device 10a and the overheating protection device 10b of the magnetron are inserted in series with the primary circuit of the low-voltage transformer, and the magnetron is overheated abnormally and the overheating protection device 10a or the overheating When the heating protection device 10b operates, the power supply to the low-voltage transformer 15 is stopped, so that the relays 14a and 14b are opened to stop the oscillation of the magnetrons 2a and 2b. It was configured in this way.

A case where the magnetron has an overheating abnormality in the structure and circuit of the conventional example will be described. First, one of the cooling fans, for example, the cooling fan 4a fails and stops. At this time, the cooling fan 4 to the magnetron 2a
It is thought that the temperature of the magnetron 2a rises abnormally because the air blow by the a disappears. However, in fact, since the remaining cooling fan 4b is rotating normally, the air inside the high-frequency heating device is exhausted by the cooling fan 4b. Since the air inside the device has a negative pressure compared to the outside, the exhaust opening 8a in FIG.
Instead of being exhausted from the air, the intake air 11 in which outside air flows into the high-frequency heating device is generated, and the magnetron 2a is cooled by the outside air. Due to this phenomenon, for example, as shown in FIGS. 7 and 8, the mounting position of the overheating protection device 10a is at the mounting position above the magnetron 2a and close to the exhaust opening 8a of the magnetron 2a;
The high-frequency heating device is installed at the point A where the temperature becomes high during normal operation, among the point C near the side where the wind of the cooling fan 4a of the magnetron 2a enters, and the point B between the points A and C. In this case, if the cooling fan 4a stops due to a failure, the temperature at the point A becomes lower than that in the normal use, so that the overheating protection device 10a does not work and the failure of the cooling fan 4a cannot be detected. In order to easily detect the stop of the cooling fan 4a, the mounting position of the overheating protection device 10a is set to a point C where the temperature when the cooling fan 4a is stopped becomes high.
It is possible to detect the stop due to the failure of the magnetron 2a, but when the magnetron 2a breaks down while the cooling fan 4a is rotating, the temperature of the point C of the magnetron 2a remains low due to the cooling air from the cooling fan 4a and the magnetron 2a It becomes difficult to detect the failure of the device. That is, it has been difficult to detect a failure by the overheating protection device depending on whether or not the cooling fan 4a has stopped due to a failure. The relationship between the above states is shown in the graph of “Temperature at each of mounting points A, B, and C of magnetron overheating protection device and operation state of high-frequency heating device” in FIG. 3. Graph 17 shows when one of the cooling fans of the magnetron stops rotating. Graph 20 shows the case where the magnetron fails and the magnetron abnormally rises in temperature with the cooling fan rotated.

[0006]

However, in the above-described configuration, the temperature of the overheating protection device section is reduced when the magnetron is abnormally heated, such as when the cooling fan is stopped. However, there is a problem that it is difficult to detect an abnormal temperature rise.

[0007] The present invention solves the conventional problems.
It is an object of the present invention to provide a high-frequency heating apparatus capable of detecting a failure due to an overheating abnormality of a magnetron regardless of whether or not the magnetron cooling fan is stopped due to a failure.

[0008]

In order to solve the above-mentioned problems, a high-frequency heating apparatus according to the present invention has an overheating protection device attached to two or more magnetrons via a mounting bracket, and the mounting bracket is mounted on the magnetron itself. The side close to the exhaust opening of the cooling air passage is floated from the mounting surface of the magnetron, the floating portion is used as the mounting surface of the overheating protection device, and the mounting bracket is used as a foot from the mounting surface and the mounting bracket is used as the cooling air passage of the magnetron. It is configured to extend to the exhaust side and the air blowing side by the cooling fan, respectively, and to make the extended portion of the mounting bracket adhere to the mounting surface of the magnetron.

[0009]

According to the present invention, when the cooling fan of the magnetron stops due to a failure due to the above configuration, the temperature of the exhaust side of the cooling ventilation passage of the magnetron becomes low as described above, but the temperature of the air blowing side by the cooling fan becomes high. As the overheating protection device of the magnetron, the low temperature part is floated by the mounting bracket so as to be hardly affected by the low temperature, and the high temperature part can transmit the heat through the mounting bracket to operate the overheating protection device. Further, when the temperature of the magnetron abnormally rises due to a failure while the cooling fan is rotating, the temperature of the exhaust side of the cooling ventilation passage of the magnetron becomes high, and the temperature of the air blowing side by the cooling fan becomes low. At this time, the overheating protection device is not in direct contact with the high temperature part of the magnetron, but is close to the high temperature part and the temperature is somewhat lower than the direct contact, but it can still work.

[0010]

An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show an overheat protection device 10 according to the present invention.
It is a drawing in which a mounting bracket 24a for attaching a is attached to the magnetron 2a. The component configuration and circuit configuration other than the mounting bracket 24a are the same as those of the conventional example, and their functions are the same. Therefore, when one of the cooling fans described in the conventional example stops, the phenomenon that the temperature at the inlet and outlet of the cooling ventilation passage of the magnetron reverses when it is not stopped is the same. One embodiment of the present invention will be described mainly with respect to a mounting bracket for attaching an overheating protection device, and description of overlapping portions will be omitted. In the description, portions which do not appear in FIGS. 1 and 2 are the same as those of the conventional example, and the numbers of the conventional example are used. In the conventional example, the magnetron is described as the magnetron 2a and the magnetron 2b. However, the description of the present invention is the same regardless of whether the magnetron 2a side or the magnetron 2b side is described. Therefore, the description is limited to the magnetron 2a side. The graph of "Temperature at each of mounting points A, B, and C of magnetron overheating protection device and operating state of high-frequency heating device" in FIG. 3 is also used.

1 and 2, the yoke 25 of the magnetron 2a is used.
Mounting bracket 24a is attached to the overheating protection device 2.
4a is attached. Oscillator 27 of magnetron body
Is transmitted to the heat sink 26 and the yoke 25 around the heat sink. This heat is cooled by the wind sent by the cooling fan 4a, and the wind is discharged to the exhaust opening side of the magnetron 2a. Points A, B, and C on the yoke 25 and point D on the mounting bracket 24a are shown in FIG.
This is the temperature measurement point described in FIG.

The case where the cooling fan 4a described in the conventional example stops due to a failure or the case where the magnetron 2a is abnormally heated while the cooling fan 4a is rotating is described in the conventional example with reference to graphs 17 and 20 in FIG. It is as follows. Although not described in the conventional example, the following points are also necessary and described in the present invention. This is a characteristic of the temperature at the point C on the yoke 25. The high-frequency heating device is operated in a normal state in which the cooling fan 4a rotates, and an operation of completely stopping the operation is performed. Then, the temperature on the yoke 25 may be higher than the temperature during the operation after the operation is completely stopped. This rises due to the influence of heat from the high-pressure transformer 12a and the heating chamber 1 near the magnetron. In this case, the operation is stopped and natural cooling is performed, so that the point C far from the exhaust opening of the magnetron 2a is less likely to be naturally cooled than the point A, so that the temperature increases. In FIG. 3, a graph 22 shows a state during normal operation, and a graph 19 shows a state when the operation is completely stopped. Similarly, graph 21 shows a state during operation without applying a load to the heating chamber, and graph 18 shows a state when the operation of graph 21 is completely stopped. Here, in the state of the graph 18, the point C is operated without applying a load to the heating chamber 1 and then completely stopped and left to stand, the point C rises to a temperature at which the overheating protection device works, and a point A represents a temperature below the working temperature. ing. That is, it can be said that the mounting position of the overheating protection device is preferably point A, which has less influence after the operation is stopped.

An overheating protection device 1 according to one embodiment of the present invention will now be described.
The mounting bracket 24a of No. 0a will be described. This is a countermeasure against the possibility that the overheating protection device 10a may not work depending on whether the cooling fan 4a of the magnetron 2a stops due to a failure or not. The position of the overheating protection device 10a is a portion close to the point A due to the above-mentioned problem of temperature rise after the operation is stopped. First, the cooling fan 4a is stopped due to a failure. In this case, as described in the conventional example, the temperature at the point A becomes lower than when the high-frequency heating device is normally operated. Cannot be directly attached to Then mounting bracket 2
4a floats from the yoke 25 and suppresses the influence of the point A having a lower temperature. The heat for operating the overheating protection device utilizes the temperature at the point C in the graph 17 of FIG. The temperature of the point C is high because the heat of the oscillating portion 27 of the main body of the magnetron 2a moves to the point C side by the intake air 11 flowing from the exhaust opening 8a. This heat is used to extend the mounting bracket 24a to the point C side and move the fitting 24a in close contact with the yoke 25. And as a result C of graph 17
Temperature slightly lower than the point, but overheating protection device 10a
Can be set to a point D at which a temperature equal to or higher than the operating temperature is secured.

Next, the case where the magnetron 2a breaks down and the temperature rises abnormally with the cooling fan 4a rotating normally, but at this time, since the cooling fan 4a is rotating normally, the main body of the magnetron 2a is closed. Since the heat of the oscillating unit 27 moves to the point A side, the temperature of the point A becomes high and the temperature of the point C is low.
At this time, the heat required for the overheating protection device 10a to operate in the shape of the above-described mounting bracket 24a is used to extend the mounting bracket 24a so as to be in close contact with the point A.
Although there is some influence of the heat being drawn toward the feet of the cooling fan 4a, the heat from the contact portion at the point A of the mounting bracket 24a is
Since a is rotating normally, it is sufficiently supplied, and as a result, it is possible to raise the temperature at which the overheating protection device 10a operates. In this case as well, the temperature is lower than the temperature of the point A above the yoke 25, but the temperature of the mounting bracket 24a can be set around the point D which is equal to or higher than the operating temperature of the overheating protection device 10a. Therefore, when the mounting bracket is formed as shown in FIGS. 1 and 2, the overheating protection device can be operated regardless of whether or not the cooling fan stops due to a failure.

[0016]

As described above, according to the high-frequency heating device of the present invention, the following effects can be obtained.

(1) In a high-frequency heating device having two or more magnetrons and two or more cooling fans for cooling them, it is difficult to detect a failure due to abnormal heating of the magnetron when one of the cooling fans stops. In contrast, by adding a simple mounting bracket of the present invention, detection can be performed with only one overheating protection device.

[Brief description of the drawings]

FIG. 1 is a perspective view of a magnetron according to an embodiment of the present invention, in which a mounting bracket for mounting an overheating protection device is attached.

FIG. 2 is a cross-sectional view of a main part in the direction of arrows (a)-(b) in FIG.

FIG. 3 is a diagram showing a temperature distribution of a magnetron overheating protection device and an operation state of a high-frequency heating device.

FIG. 4 is a side view of a conventional high-frequency heating device.

FIG. 5 is a rear view of a conventional high-frequency heating device.

FIG. 6 is a circuit diagram of a conventional high-frequency heating device.

FIG. 7 is a perspective view of a magnetron of a conventional high-frequency heating device when an overheating protection device is attached.

FIG. 8 is a cross-sectional view of a main part in the direction of arrow (a)-(b) in FIG.

[Explanation of symbols]

 2a, 2b Magnetron 4a, 4b Cooling fan 10a, 10b Overheating protection device 24a, 24b Mounting bracket

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H05B 6/64 F24C 7/02 511

Claims (1)

(57) [Claims] 1. Two or more magnetrons, two or more cooling fans for cooling said respective magnetrons,
An overheating protection device for the magnetron, and a mounting bracket for mounting the overheating protection device, wherein the side of the mounting bracket near the exhaust opening of the cooling air passage of the magnetron itself floats from the mounting surface of the magnetron; The floating part is used as a mounting surface of the overheating protection device, and the mounting bracket is extended from the mounting surface to the exhaust side of the cooling air passage of the magnetron and the blowing side by the cooling fan as a foot of the mounting metal, respectively. A high-frequency heating device in which an extension of the mounting bracket is closely attached to a mounting surface.