JPS62100973A - Radio frequency heater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to cooling fJJ of each electrical component installed in a machine room.
This invention relates to a high-frequency heating device with an improved I structure.

[Technical background of the invention and its problems]

Generally, as shown in FIG. 6, a high-frequency heating device such as a microwave oven has a heating chamber 2 and a machine chamber 3 formed inside a high-frequency heating device main body 1, and a magnetron (high-frequency oscillator) 4 inside this machine chamber 3. ．． A high voltage transformer 5 that drives this magnetron 4. A configuration is known in which a high-voltage capacitor and other electrical components are mounted, and a cooling fan 6 is mounted to cool these electrical components. In this case, the magnetron 4 is heated up to 2
The waveguide 7 is attached in a suspended state to the base end of the waveguide 7 fixed to the top plate 2a. Further, the high voltage transformer 5 is attached to the floor plate 3a of the machine room 3 by screws or the like. In addition, 8 is an operation panel arranged on the front side of the high-frequency heating device main body 1, 9 is another electric component attached to the back side of this operation panel 8, and 10 is formed on the rear plate 3b of the separate machine 3. It is an intake port.

By the way, when the magnetron 4 is driven, the magnetron 4
Since the high voltage transformer 5 generates heat at a relatively high temperature, it is necessary to cool the magnetron 4 and the high voltage transformer 5 intensively using the cooling fan 6. however,
One cooling fan 6 is installed in the machine room 3, and the cooling f! from this cooling fan 6 is provided. When J wind is blown onto the magnetron 4 and the high-voltage transformer 5, and the magnetron 4 and the high-voltage transformer 5 are simultaneously cooled, the direction of the cooling air blown from the cooling fan 6 is determined by the direction of the magnetron 4 and the high-voltage transformer 5. There is a problem that if there is separation from one side of the two, the cooling effect on the other side decreases.

Therefore, in the conventional configuration, the cooling fan 6 is disposed at a position corresponding to the intermediate position between the magnetron 4 and the high voltage transformer 5, and the cooling fan 6 hl etc.
was sprayed onto the magnetron 4 and high voltage transformer 5 approximately evenly. However, in the conventional configuration described above, the largest amount of cooling air blown from the cooling fan 6 flows into the gap between the magnetron 4 and the high-voltage transformer 5, so the cooling effect of the magnetron 4 and the high-voltage transformer 5 is low. There was an easy problem. Furthermore, the flow of cooling air around the magnetron 4 (high voltage transformer 5) is
As shown in the figure, since the flow is maintained in a substantially laminar state, the amount of cooling air actually blown onto the surface of the magnetron 4 (high-voltage transformer 5) is relatively small, and the cooling effect of the magnetron 4 (high-voltage transformer 5) is There was a problem in trying to improve the performance.

It is also possible to improve the cooling effect of the magnetron 4 and the high voltage transformer 5 by reducing the gap between the magnetron 4 and the high voltage transformer 5. However, when mounting the magnetron 4 at a lower position, it is necessary to provide a bent part in the waveguide 7 in an abbreviated shape and attach the magnetron 4 in a suspended state to this bent part. There was a problem in that the wave tube 7 had a special shape, resulting in high cost. Furthermore, if the high-voltage transformer 5 is to be mounted in a higher position, a stand or the like is required for mounting the high-voltage transformer 5, which increases the cost and increases the height of the high-voltage transformer 5.
There was also the problem of poor stability due to the higher center of gravity.

[Purpose of the invention]

This invention provides high-frequency heating that can improve the cooling effect of the electrical components that are to be cooled intensively among the electrical components installed in the machine room, and can also prevent increases in cost and deterioration of stability. The purpose is to provide a device.

[Summary of the invention]

In this invention, a machine chamber is formed within the main body of the high-frequency heating device,
In the high-frequency heating device, electrical components such as a high-frequency oscillator, a high-voltage transformer for driving the high-frequency oscillator, and a high-voltage capacitor are installed in the machine room, and a cooling fan for cooling each of these electrical components is installed. The present invention is characterized in that a vortex forming member for forming a vortex in the cooling air blown out from the cooling fan is disposed between the fan and the electrical components to be intensively cooled.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5. FIG. 1 schematically shows the inside structure of a machine room 11 of a high-frequency heating device such as a microwave oven. Inside this machine room 11 is a magnetron (high frequency oscillator) 12.
A high voltage transformer 13 that drives this magnetron 12. A cooling fan 14 is provided with a high-voltage capacitor and other electrical components, and cools these electrical components.
is installed. In this case, the magnetron 12 is attached in a suspended state to the base end of a waveguide 16 fixed to the top plate 15a of the heating chamber 15. In addition, high voltage transformer 13
is the floorboard 11. of the machine room 11. It is attached to a by screws or other means. Furthermore, the cooling fan 14
11 is attached to the rear plate 11b. For example, louver-shaped intake ports 17 are formed on the rear plate 11b of the machine room 11 above and below the cooling fan 14, respectively.

On the other hand, a vortex forming member 18 for forming a vortex in the cooling air blown out from the cooling fan 14 is disposed between the cooling fan 14 and electrical components to be intensively cooled, that is, the magnetron 12 and the high-voltage transformer 13. . As shown in FIG. 2, this vortex forming member 18 has a large number of circular holes 20 arranged in a substantially staggered manner on the surface of one substrate.
The aperture ratio of the circular holes 20 to the plate surface of the substrate 19 is approximately 6.
It is set to about 0% (60±5%). Furthermore, this vortex forming member 18 has an upper portion 18a and a lower portion 18b.
A step portion 21 is formed between the two. In this case, the upper part 18a of the vortex forming member 18 is connected to the magnetron 12,
Further, the lower portion 18b is disposed opposite to the high voltage transformer 13 at a distance from each other.

The spacing 21 between the magnetron 12 and the upper part 18a and the spacing 22 between the high voltage transformer 13 and the lower part 18b are each set at equal intervals of ¥A, for example, a spacing of 21 degrees. 2 are each set to about 10 m.

Further, a magnetron 1 is provided on the downstream side of the magnetron 12 with respect to the flow direction of the cooling air blown out from the cooling fan 14.
A duct 22 is provided for introducing the cold fiflffl blown onto the heating chamber 15 into the heating chamber 15. This duct 2
As shown in FIG. 3, the duct 2 is formed by the top plate 15a of the heating chamber 15, the side plate 15b, and a duct component member 23 whose cross-sectional shape is bent into an oval shape.
In the side plate 15b of the heating chamber 15 corresponding to the 11th end portion of No. 2, air introduction holes 24, which are formed by, for example, a large number of punched holes, are formed. Furthermore, this duct 2
2 has an air introduction hole 24 in the side plate 15b of the heating chamber 15.
A lamp 25 for illuminating the inside of the heating chamber 15 is disposed at a location corresponding to . In this case, the top plate 1 of the heating chamber 15
5a is formed with a cut-and-raised piece 26 that is cut and raised upward as shown in FIG.
A lamp holder 25a of the lamp 25 is fixed to 6.

Therefore, in the configuration described above, vortices and currents are formed in the cooling air blown from the cooling fan 14 between the cooling fan 14 and the electrical components to be mainly cooled, that is, the magnetron 12 and the high-voltage transformer 13. Eddy flow forming member 18
is provided, so that when the cooling fan 14 is in operation, the cooling air blown out from the cooling fan 14 flows through the vortex forming member 18.
When passing through each circular hole 2O..., the flow path of the cooling air can be narrowed by each circular hole 20..., and the flow velocity of the cold fIIi can be increased, and the cooling air flows into the vortex forming member 18. When passing through each circular hole 20..., each circular hole 20.
As shown by the arrows in FIG. 5, many vortices can be formed in the flow of cooling air, and turbulence can be created in the flow of cooling air. Therefore, the vortex forming member 18
The turbulent cooling air that has passed through each circular hole 20 is sent to the magnetron 12 and the high pressure lance 13 at a relatively high speed.
Therefore, the cooling effect of the magnetron 12 and the high-voltage transformer 13 can be improved compared to the case where substantially laminar cooling air is blown onto the magnetron 12 and the high-voltage transformer 13. In this case, the cooling effect Num due to the cooling air can be expressed by the following equation.

Null -CI ・Red"・Pr'-
CI, m+coefficient, Rcd: Reynolds number, Pr Nybrandtl number. Here, each Red, CI of the cold FA wind in a laminar flow state and the cooling wind in a turbulent flow state.

The values of m and pr are shown in the table below.

is Num=0.92X40'-38! l Xo, 6” Cape 3
, 21 In addition, the cooling effect Nu of the cooling air in the turbulent flow (eddy flow) state is Num=0,159X4x1Q3('-”8)x1+#
32.8, so compared to the case where substantially laminar cooling air is blown onto the magnetron 12 and high-voltage transformer 13, the case where turbulent (vortex) cooling air is blown onto the magnetron 12 and high-voltage transformer 13 is It can be seen that the cooling effect of the magnetron 12 and the high-voltage transformer 13 can be improved.

Furthermore, the frontage ratio of the circular hole 20 to the plate surface of the 1Nffi 19 of the vortex forming member 18 is approximately 60% (60±5
%), and the spacing 21 between the magnetron 12 and the upper part 18a and the spacing 22 between the high voltage transformer 13 and the lower part 18b are set to 10a, respectively.
m, each circular hole 20 of the vortex forming member 18
The turbulent cooling air that has passed through can be blown onto the magnetron 12I3 and the high-pressure transformer 13 more effectively. In this case, if the aperture ratio of the circular holes 20 of the vortex forming member 18 with respect to the plate surface of the substrate 19 is set to 50% or less, the ventilation resistance of the cooling air due to the vortex forming member 18 will increase, so the ventilation of the entire cooling air will be reduced. There is a problem that the amount of cooling air decreases, and conversely, if the aperture ratio of the circular holes 20 of the vortex forming member 18 to the plate surface of the substrate 19 is set larger than the range of 60±5%, the flow velocity of the cooling air decreases. , since the eddy current also becomes weaker, there is a problem that the cooling effect decreases. Note that the aperture ratio of the circular holes 20 with respect to the plate surface of the substrate 19 of the vortex forming member 18 is set to approximately 6% (60±5%), and the distance between the magnetron 12 and the upper portion 18a is By setting the interval ρl and the separation interval 22 between the high-voltage transformer 13 and the lower part 18b to about 10 seconds, the anode temperature of the magnetron 12 during high-frequency heating is lowered from the conventional about 180°C to about 160°C. Therefore, the durability and reliability of the magnetron 12 can be improved. Furthermore, 1 of the high voltage transformer 13
The temperature of the next winding has been changed from the conventional 135℃ to 120℃.
The temperature of the secondary winding can be lowered from the conventional 138°C to around 122°C, and the wire diameter of the primary winding of the high voltage transformer 13 can be reduced by about 7% and the wire diameter of the secondary winding can be reduced by about 13%. %, the entire high voltage transformer 13 can be made smaller and lighter, and the cost can be reduced.

Furthermore, since there is no need to make the gap between the magnetron 12 and the high voltage transformer 13 particularly small, the waveguide 1
There is no need to make the transformer 6 into a special shape or to use a stand for mounting the high voltage transformer 13, and it is possible to prevent an increase in cost and deterioration of stability.

Further, a cut-and-raised piece 26 is formed on the top plate 15a of the heating chamber 15 to introduce the cooling air blown to the magnetron 12 into the inside of the heating chamber 15.]
- Since the lamp holder 25a of the illumination lamp 25 disposed inside the duct 22 is attached to this cut-up piece 26, the illumination lamp 25 can be installed without any cold water leaking to the outside of the duct 22 through the opening. The top plate 15a of the heating chamber 15
can be guided upwards. Therefore, a portion of the high-temperature cooling air flowing inside the duct 22 is transferred to the lighting lamp 25.
Since the attachment can reliably prevent water from flowing into the machine room 11 through the opening, the temperature rise in the machine room 11 can be reduced. Note that a cut-and-raised piece 26 is formed on the top plate 15a of the heating chamber 15 and is arranged inside the duct 22 that introduces the cooling air blown to the magnetron 12 into the inside of the heating chamber 15. By attaching the lamp holder 25a of the illumination lamp 25 to this cut-and-raised piece 26, when the temperature inside the conventional machine room 11 during high-frequency heating is, for example, about 70°C,
It is possible to lower the temperature of the magnetron 12 from the conventional 170'C to about 160'C, thereby improving the durability and reliability of the magnetron 12. The temperature of the transformer 13 can be lowered from the conventional level of about 126°C to about 108°C, making it possible to reduce the overall size and weight of the high-voltage transformer 13 and reduce the amount of varnish. Further, since the illumination lamp 25 can be attached and removed from the upper side of the heating chamber 15, the work of replacing the illumination lamp 25 can be facilitated.

Note that this invention is not limited to the above embodiments. For example, the vortex forming member 18 may be formed of expanded metal, and it goes without saying that various other modifications can be made without departing from the spirit of the invention.

〔Effect of the invention〕

According to this invention, a vortex forming member that forms a vortex in the cooling air blown from the cooling fan is disposed between the cooling fan and the electrical components to be intensively cooled, so that each electrical component installed in the machine room Among them, it is possible to improve the cooling effect of the electrical components that are mainly cooled, and it is also possible to prevent increases in cost and deterioration of stability.

[Brief Description of the Drawings] Figures 1 to 5 show an embodiment of the present invention.
Fig. 1 is a vertical cross-sectional view showing the schematic structure of the inside of the microwave oven, Fig. 2 is a perspective view showing the vortex forming member, and Fig. 3 is a longitudinal cross-sectional view of the main parts showing how the illumination lamp is installed. , FIG. 4 is a perspective view showing a cut-and-raised piece for mounting an illumination lamp formed on the top plate of the heating chamber, FIG. Figures 6 and 7 show conventional examples; Figure 6 is a vertical cross-sectional view showing the schematic internal structure of the microwave oven, and Figure 7 is a schematic diagram of the main parts showing the flow state of cold fJllil. FIG. DESCRIPTION OF SYMBOLS 11... Machine room, 12... Magnetron (high frequency oscillator), 13... High voltage transformer, 14... Cooling fan, 18... Eddy current forming member. Applicant's agent Patent attorney Takehiko Suzue χ2 Figure 1 Figure 5 Figure 7F;! ? I

Claims (2)

[Claims] (1) A machine room is formed in the main body of the high-frequency heating device, and electrical parts such as a high-frequency oscillator, a high-voltage transformer that drives this high-frequency oscillator, and a high-voltage capacitor are installed in this machine room, and each of these electrical parts is In a high-frequency heating device equipped with a cooling fan for cooling, a vortex forming member for forming a vortex in the cooling air blown out from the cooling fan is disposed between the cooling fan and electrical components to be intensively cooled. A high-frequency heating device featuring: (2) The vortex forming member is installed at equal intervals with respect to a plurality of electrical components to be intensively cooled, respectively. The high-frequency heating device described in (1).