JPS59198693A - High 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 Field of the Invention The present invention relates to a high-frequency heating device, such as a microwave oven, that performs heating using radio waves.

Structure of conventional example and its problems The conventional high frequency heating apparatus shown in FIGS. 1 and 2, for example, had the following problems.

FIG. 1 is a front sectional view showing the structure of a conventional high-frequency heating device, and FIG. 2 is a side sectional view of the same device.

Identical parts are indicated by the same numbers in FIGS. 1 and 2, and the conventional structure and problems will be explained below using FIGS. 1 and 2 together.

In FIGS. 1 and 2, a heating chamber 1 is provided with a door 2 that can be opened and closed. A waveguide 3 is connected and provided on the upper surface of the heating chamber 1, and a magnetron 4, which is an oscillator, is attached.

The configuration is such that radio waves are irradiated into the heating chamber 1 through a waveguide 3. A power transformer 5 is provided at the bottom of the main body to supply high voltage current to the magnetron 4. Since the magnetron 4 generates high heat during oscillation, a blower 6 is installed to cool it down. Cooling air is drawn into the main unit from the intake lower as shown by the arrow.
After cooling the magnetron 4, it passes through the duct 8f and enters the heating chamber 1 through an opening 9 provided on the side surface of the heating chamber 1. The inside of the heating chamber 1 is ventilated and the air is discharged to the outside of the heating chamber 1 through an exhaust port 10. A portion of the air blown by the blower 6 passes through the upper part of the power transformer 5, cools it, and then is discharged to the outside of the main body through an exhaust port 11 at the bottom of the main body.

According to such a conventional high-frequency heating device, the power transformer 5 is cooled by the blower 6.
The cooling air (as shown by the solid arrow) only passes through the surface of the power transformer 50.The iron core 1 has a small heat capacity and is composed of a stack of steel plates ((therefore, since it is composed of a stack of steel plates, thermal insulation is achieved between the layers). , heat conduction is poor, and the central part inevitably becomes cold and the temperature rises.This also causes the winding temperature to rise.The lifespan of electrical components is affected by temperature rise, and if sufficient cooling is not achieved, the temperature will rise. In order to lower the temperature rise, the lifespan will be shortened.
The lance 5 requires a large power capacity, which is not only expensive, but also makes the device itself large and heavy, so it takes up a lot of space and is difficult to transport. Object of the Invention The present invention solves the above-mentioned drawbacks of the conventional technology.The present invention aims to reduce the size and weight of the power transformer by effectively cooling the C1 oscillator and the entire power transformer with an air blower. The overall purpose is to realize a compact and easy-to-use sail surface frequency caloric heating device.

Structure of the Invention In order to achieve all of the above objects, the high frequency heating device of the present invention has the following features:
There are many ventilation holes in the iron core of the power transformer, and cooling air from a blower is blown through these ventilation holes to cool the inside of the iron core. It also attempts to blow air inside. The iron core itself has a large heat capacity, and heat is trapped inside the core, making it difficult to get cold. However, by forcing air cooling to this central part, the core is cooled, and the winding temperature is also lowered, making it possible to create a compact power transformer, which is also lightweight. This makes it possible to realize a comprehensive high-frequency heating device that is effective at any time.

EXAMPLE Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 3 is a perspective view showing the structure of the power transformer of the high frequency heating device according to the present invention. In FIG. 3, the iron core 16 is constructed by stacking steel plates with good magnetic properties, such as silicon steel plates. A primary coil 16 and a secondary coil 17 are wound around the iron core 16. A Nyanto iron core 18 is provided between the primary coil 16 and the secondary coil 17 to leak a part of the magnetic flux, and as a result, it can be used in combination with a separately provided capacitor as a magnetic leakage type transformer. : The structure has a resonance characteristic and stabilizes the output against voltage fluctuations. For this reason, the primary coil 16 and the secondary coil 170 are separated by the thickness of the shunt core 18.

The legs 19 are fixed to the iron core 15 by spring screws, welding, etc. A plurality of ventilation through holes 20 are provided in the periphery of the iron core 15 or in the middle portion formed by the Yant iron core 18.

FIG. 4 is a front sectional view showing the structure of the high-frequency heating device according to the present invention, and FIG. 5 is a side sectional view of the same device. Figure 4,
Identical parts in FIG. 5 are designated by the same reference numerals, and will be explained below using both FIGS. 4 and 5 together. 4 and 5, the heating chamber 21 is provided with a door 22 which can be opened and closed.

A waveguide 23ff is provided in the heating chamber 21, and a magnetron 24 serving as an oscillator is completely attached. The configuration is such that radio waves are irradiated into the heating chamber 21 through a waveguide 23. A power transformer 25 is provided at the bottom of the main body, and all high voltage current is supplied to the magnetron 24 through one node. A blower 26 is provided behind the magnetron 24 and power transformer 25. A plurality of ventilation through holes 20 are provided in the iron core of the power transformer 25, and the ventilation through holes 20 are configured to face the direction of air blowing from the blower 26. The cooling air is drawn into the main body from the intake port 27 as shown by the arrow, and the magnetron 2
4 and the power transformer 25 evenly. Magne,
The wind that cooled the tron 24 passes through the duct 28 to the heating chamber 2.
It enters into the heating chamber 21 through the opening 29 provided on the 4jl11 surface of 1.

The heating chamber 21 is ventilated and the heating chamber 21 is ventilated through the exhaust port so'1.
release it outside. On the other hand, the power transformer 25 is cooled by being divided into wind flowing on the outer peripheral surface and wind passing through the ventilation through holes 20.

After that, the cooling air passes through the exhaust port 31 at the bottom of the main body and is discharged to the outside of the main body. The partition plate 32 is provided to effectively blow air from the blower 26.

The operation in the above structure Fi3: will be explained below.

Figure 6 shows the power transformer 2 of the high frequency heating device according to the present invention.
State of heat transfer and magnetic flux in 5? FIG. 2 is a cross-sectional view of a power transformer 25 for explanation. A primary coil 16 and a secondary coil 17 are wound around the iron core 15. 18 is the Nyant iron core. The iron core has 20-karat gold ventilation holes. When current flows through the primary coil 16 and the secondary coil 17, winding resistance causes copper noise loss and heat generation, causing the coils to reach high temperatures. The heat of this coil is transferred to the iron core 15 as shown by the solid line arrow.The heat transferred to the iron core is transferred to the surface of the outer circumferential surface, and is radiated into the air by air cooling as shown by the broken line. Since there is no way for heat to escape in the central part of the iron core 15, the heat is radiated by heating or freezing to the central part shown by diagonal lines.
o is provided, so the heat in the central part is dissipated through this ventilation through hole 20.
% - Heat will be exchanged by the passing cooling air and radiated into the air. Due to the action of C, the vicinity of the center of the core, where there is a heat trap, is also well cooled. Of course, if ventilation through holes are provided in the outer periphery, heat is radiated not only from the surface of the thermal FD core but also from the ventilation through holes, thereby increasing the cooling effect. Since the iron core surface provided with the ventilation through holes 20 faces the blower 26, the cooling air from the blower 26 is forced to pass through the ventilation through holes 20, effectively cooling the iron core 15, and making contact with the iron core 15. The primary coil 16 and secondary coil 17 are also cooled to a low temperature.

On the other hand, the state of magnetic flux is shown by a two-dot chain line. The magnetic flux generated by the primary coil 16 passes through the secondary coil 17, and a portion of the magnetic flux flows to the iron core 18. Due to the action of the magnetic flux flowing to the shunt core 18, magnetic saturation occurs within the core, and the transformer itself becomes characterized by an inductive L component. Due to the capacitive C component caused by the capacitor installed in the external circuit.

By creating C resonance and selecting the resonance point appropriately, current fluctuations can be controlled with respect to voltage fluctuations. It becomes a so-called stabilizing circuit. The ventilation through holes 20 provided in the core partially block the flow of magnetic flux within the core and allow it to flow more easily on the shunt core 18 side. This also serves to further enhance the effect of the 18-karat gold Nyote/Yant iron core.

In this way, according to this embodiment, the power transformer 2 can be effectively
5 is cooled, resulting in a high-frequency heating device with a long life and high durability. Since the power transformer 25 is small and lightweight, it is possible to realize a convenient high-frequency heating device that is lightweight, compact, does not take up much space, is easy to carry, and is easy to use.

Effects of the Invention As described above, according to the present invention, the following effects can be obtained.

(1) Power transformer 26il-j: Since it is effectively cooled by the blower 26, the power transformer 25 can be constructed of an inexpensive insulating material with a low heat resistance and can be made inexpensive. If the design is designed to have the same temperature rise, the wire diameter of the coil needs to be thinner to compensate for the cooling effect, resulting in a compact and lightweight structure that saves resources and costs less.

(2) Reducing the size and weight of the power transformer 25 also leads to the reduction in size and weight of the device, which takes up less space.

It is a high-frequency heating device that is easy to carry, convenient, and easy to use.

(3) Since the power transformer 25 is effectively cooled, the amount of air blown by the blower 26 can be reduced. As a result, the output of the blower 26 can be reduced, so that the second blower 26 can be constructed economically and inexpensively, and the power consumption can be reduced, resulting in an energy-saving design.

The miniaturization of the trench blower 26 also reduces the noise generated when blowing air, making it possible to achieve quiet operation.

(4) The ventilation through-holes 20 provided in the iron core partially block the flow of magnetic flux within the iron core, and also allow the flow to flow quickly toward the iron core 18 side. As a result, even if the number of Nyant iron cores 18 is small, it can sufficiently perform its function, and this also leads to the realization of a small and lightweight transformer.

Furthermore, since the magnetic flux density within the iron core is high, magnetic saturation is likely to occur, making the transformer even more effective as a magnetic leakage transformer.
, it is possible to further improve output stability against power supply voltage fluctuations.

(5) The laminated steel plates constituting the iron core 15 are vacuum-impregnated with varnish and brought into close contact with each other. Ventilation through hole 2Of: Through this varnish also enters the central part of the iron core, and the steel plate in the central part is also completely adhered. This completely eliminates the problem of vibration noise occurring in this part due to insufficient adhesion between the steel plates, thereby realizing a high-quality power transformer 25. Since the varnish penetrates easily, the processing time required for rapid impregnation is shortened, making manufacturing easier.

As described above, according to the present invention, although it has a simple configuration, it exhibits many effects.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view showing the structure of a conventional high-frequency heating device, FIG. 2 is a side sectional view of the same device, and FIG. 3 is a perspective view showing the structure of a power transformer of a high-frequency heating device according to an embodiment of the present invention. Figure 4 is a front sectional view showing the structure of the device, and Figure 6 is a front sectional view showing the structure of the device.
The figure is a side sectional view of the device, and Figure 6 is a sectional view of the power transformer of the device.
1 Complete... Secondary coil, 18... Nyantoko 7+-120..."°. Ventilation through hole, 25... Power transformer, 26...
····Blower. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] An oscillator that supplies radio waves into the heating chamber, a power transformer that supplies power to the oscillator, and a cooling blower are provided, and the power transformer is an air leakage transformer that has a shunt core between the primary coil and the secondary coil, A high-frequency heating device comprising: a ventilation through-hole provided in an iron core including at least a gap between a primary coil and a secondary coil; and a blower disposed at a position facing the ventilation through-hole.