JPH046265B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a method for enclosing a high-voltage secondary circuit with a metal body,
This invention relates to a high-frequency heating device that prevents electric shock accidents caused by high voltage on the secondary side by preventing contact with the power source side.

Conventional technology In the unlikely event that insulation deteriorates between the high-voltage secondary circuit and the power supply side, and high voltage leaks to accessible metal parts of the range, the conventional high-frequency heating device (hereinafter simply referred to as the range) This is an attempt to ensure safety by installing a ground terminal on an accessible metal part and performing grounding work to the earth to bypass the current leakage current and reduce the current flowing to the human body to a safe level. Ta.

Problems to be Solved by the Invention However, even if a grounding terminal is provided, grounding work must be done after purchasing the stove, and it may not be carried out for various reasons, and even if it is done, the grounding resistance The value is around 100Ω, but in reality it is close to 200Ω to 300Ω, and the human body resistance
Considering the worst case of about 500 Ω, the electric shock current flowing through the human body will be several amperes if a high voltage of nearly 2000V leaks, and the electric shock current will be reduced to a value of 1 mA or less, which is said to be a safe level for the human body. I couldn't push myself to the bottom.

The present invention solves these conventional problems, and makes the high-voltage secondary side circuit with a simple structure that prevents leakage of electricity to the power supply side, thereby preventing electric shock accidents caused by high voltage on the secondary side. The present invention provides a high frequency heating device that prevents

Means for Solving the Problems The present invention surrounds the high voltage secondary side circuit with a metal body,
In order to prevent contact with the power supply side, the core of the high-voltage transformer is laid out on the chassis outside the metal chassis that houses the heating chamber and high-frequency generator.
The metal case of the high-voltage capacitor, the metal case of the magnetron oscillator, and the metal wall constructed by adding a cross-contact prevention plate electrically connected to the core and fixed between the high-voltage secondary coil and the power supply side primary coil of the high-voltage transformer. Therefore, in effect, the high voltage secondary circuit is
It is enclosed and has a configuration that prevents direct contact with the power supply side.

Function: In addition to the conventional high-voltage transformer core, high-voltage capacitor metal case, and magnetron metal case, the microwave oven of the present invention is surrounded on all sides by metal plates that are electrically connected and fixed to the high-voltage transformer core. Another aspect is that by confining the high-voltage secondary circuit within the space made up of the heating chamber and chassis, in the unlikely event that the insulation of the high-voltage section deteriorates, one end of the secondary side of the high-voltage transformer can be connected to the chassis. Therefore, a closed circuit is created within the secondary circuit, and insulation from the power supply side is maintained, so no cross contact occurs.

In this case, the situation is similar to the case where the high-voltage rectifier has dielectric breakdown, and the fuse in the power supply circuit blows to notify the failure state, as in the case of conventional ranges.

Therefore, there is no risk of electric shock due to insulation deterioration on the high voltage side, and safety can be ensured.

Embodiment Hereinafter, the configuration of a microwave oven according to an embodiment of the present invention will be described with reference to the drawings.

As shown in FIGS. 1a and 1b, a heating chamber 1 in which food is stored and cooked is equipped with a magnetron oscillator 2.
High frequency waves are emitted from the The high-voltage transformer 3 that drives the magnetron 2 is an insulating transformer that is divided into a power source coil 4 and a secondary high-voltage coil 5, and one end of the secondary high-voltage coil 5 is electrically coupled to a metal chassis 6. ing. The core 7 is electrically connected and fixed to the metal chassis 6. A metal plate 8 is electrically coupled to the core 7 and fixed between the power supply side coil 4 and the secondary high voltage side coil 5.
The metal plate 8 is connected to the power supply side coil 4 as shown in the figure.
and a secondary high voltage coil 5 extend substantially perpendicularly from the core 7 at a sufficiently large height that it cannot be seen through, forming a metal wall perpendicular to the core 7. The high voltage capacitor 9 is arranged on the chassis 6 so that the metal case forms one metal wall.

That is, in the embodiment, the high voltage secondary circuit 10 includes the high voltage diode 11, the transformer core 7 disposed on the chassis 6, the metal plate 8, the metal case of the high voltage capacitor 9, and the four sides of the metal case of the magnetron 2. , is enclosed in a metal case whose top and bottom are configured by the bottom surface 12 of the heating chamber 1 and the chassis 6,
Virtually isolated from the power supply side.

In other words, the distance between the terminal section 13 and the wiring 14, which are high-voltage secondary side live parts, and the metal wall that constitutes the metal case is shorter than the distance between these live parts and the power supply side live part. Because of this structure, in the event that the insulation on the high voltage secondary side breaks down and there is a current leakage, the current will leak to a nearby metal wall and will not leak to the live parts on the power supply side.

The power supply side charging section includes the primary coil 4 of the high voltage transformer 3 shown in the figure, the terminal section 15, the fan motor coil 16,
This corresponds to the latch switch 17, time switch 18, power cord 19, and power supply side low voltage wiring 20.

These charging parts on the power supply side are shielded by the transformer core 7, metal plate 8, and magnetron 2.
The distance to the secondary high-voltage live part is sufficiently larger than the distance between the high-voltage secondary live part and the metal wall that makes up the metal case (about twice or more is better), so contact may occur due to insulation deterioration. It has a fearless structure.

The electrical continuity between these metal walls is through the mounting screws 21 of the magnetron 2 and the fixing screws 22 of the heating chamber 1 and chassis 6.
Further, it is secured by fixing screws (not shown) of the high voltage transformer 3 and the high voltage capacitor 9. In FIG. 2, the primary coil 4 has a double insulator 24 consisting of basic insulation and additional insulator extending from the core 7 by 8 mm or more, and the primary coil 4 side of the metal plate 8 has a double insulator 24 consisting of basic insulation and additional insulation. A double insulation board 23 consisting of basic insulation and additional insulation is applied. Returning to Figure 1,
The primary coil terminal 15 is provided on the side opposite to the high voltage secondary side terminal 13 with respect to the power supply circuit side.

Referring to FIG. 3, a method for doubly insulating the power supply side low-voltage wiring 20 from the chassis and heating chamber will be described.
The fan motor bracket 25 to which the resin fan motor mounting plate and air guide are attached is provided with a flange 27 having a groove 26 in a direction perpendicular to the direction in which the low voltage wiring 20 is routed. for a given spatial distance, e.g. 2.4
mm or more. When wiring, pass the lead wire along this groove 26, and then connect it to the terminal 15 of the transformer primary coil 4 or the fan motor coil 16.
Insert it into the terminal. By managing and bundling the wiring with a small length allowance so that the wiring does not come loose, the bottom pressure wiring 20 has a flange 27, so there is always a space of 2.4 mm or more between it and the metal wall of the heating chamber bottom 12 above. Distance is maintained. Therefore, by using the insulation coating of the low voltage wiring 20 as basic insulation and using the 2.4 mm spatial distance as additional insulation, double insulation can be achieved with a simple structure from the metal wall 12 and the chassis 6.

Effects of the Invention As described above, in the microwave oven of the present invention, since the secondary high voltage side is substantially enclosed by the metal wall, in the unlikely event that the secondary side insulator etc. deteriorates and the metal wall Even if there is a leakage between There is no fear of electric shock due to voltage.

In addition, instead of adding a special metal wall to the secondary high voltage side, we will improve the arrangement of the high voltage components such as the core of the transformer, the metal case of the high voltage capacitor, and the magnetron, and the metal plate installed on the high voltage transformer to prevent cross contact. Since the structure is made up of only one component, the number of parts is small, the effect of preventing contact between the power supply side and the high voltage side is ensured, and the length of the high voltage wiring can be shortened, which is extremely effective in practical terms.

[Brief explanation of drawings]

Figures 1a and 1b are a plan view of a chassis housing a high-frequency generator for a microwave oven according to an embodiment of the present invention;
The figure is a perspective view showing the high voltage transformer of the present invention.
The figure is a perspective view showing a fan motor bracket for double insulating the low-voltage internal wiring on the power supply side of the present invention. 1... Heating chamber, 2... Magnetron oscillator, 3
...High voltage transformer, 6...Metal chassis, 7...
Core, 8...Metal plate, 9...High voltage capacitor,
10... High voltage secondary side circuit, 11... High voltage diode.

Claims (1)

[Claims] 1 A heating chamber in which food is stored and cooked in the main body, a high-frequency generator that radiates high-frequency waves into the heating chamber, a metal chassis that houses the high-frequency generator, and one end of the secondary side of the insulation transformer connected to the chassis or transformer. A high voltage transformer electrically coupled to at least one of the cores, a high voltage capacitor having a metal case connected to a high voltage secondary circuit, and a magnetron oscillator also having a metal case are disposed on the chassis. The high-voltage secondary coil and the power supply side primary coil are wound separately.
and a metal plate directly connected and fixed to the transformer core between them, and the high voltage secondary circuit is surrounded by the core of the high voltage transformer, the metal plate, the metal case of the high voltage capacitor, the metal case of the magnetron, and the metal chassis. The metal parts are electrically connected to each other, and the distance from at least the high voltage secondary side live part is shorter than the distance from the power supply side live part, so that the high voltage secondary side is substantially made of metal. A high-frequency heating device that is enclosed by a wall to prevent contact with the power supply side.