JPS6323865Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to improvements in magnetrons used in microwave ovens and the like.

[Technical background of the invention]

A conventional magnetron is constructed as shown in FIG. 1. Reference numeral 1 denotes an oscillating section body, and 2 and 3 denote a cathode stem and an output section, respectively, which are protruded from the oscillating section body 1 .
Further, 4 and 5 are annular permanent magnets coaxially disposed outside the cathode stem 2 and the output section 3. Reference numeral 6 denotes a frame-shaped yoke made of a magnetic material that is magnetically connected to the permanent magnets 4 and 5 to form a magnetic circuit. or,
Reference numerals 7 and 8 denote a choke coil and a feedthrough capacitor connected in series to the cathode stem 2, which constitute a filter and suppress noise from the magnetron. Further, numeral 9 denotes a bottomed shield box without holes, which surrounds a portion of the cathode stem 2, choke coil 7, and feedthrough capacitor 8 to prevent leakage of radio waves from the cathode side of the magnetron.
In the figure, numeral 10 represents a plurality of fins, and arrow 11 represents cooling air.

By the way, although not shown in the diagram, the cathodes of magnetrons currently used are made of thorium tungsten and have an operating temperature of approximately 1700°C, so the temperature of the cathode stem 2 can reach over 300°C, reducing reliability. I'm letting you do it. In addition, in order to improve the filter characteristics, the Chi York coil 7 uses a ferrite magnetic core that has excellent radio wave absorption ability, so it absorbs the leakage power from the magnetron, and depending on the usage conditions, it can reach a temperature of about 200℃. , it may burn out.

Therefore, in order to reduce the temperature rise inside these shield boxes 9, as shown in FIG. A magnetron having a structure in which the section 11a is cooled by passing it through the shield box 9 is used. However, in general, this type of magnetron is often used by applying a negative high voltage to the cathode potential, and in the unlikely event that the through hole 12 of the yoke 6 and shield box 9
If a wire or the like is passed through 13, there is still a risk of high voltage shot or electric shock.

[Purpose of invention]

The purpose of this invention is to provide a highly reliable magnetron that is safe, allows ventilation to be cooled inside the shield box, and is highly reliable.

[Summary of the idea]

This idea consists of an oscillating unit body with a cathode stem and an output section protruding from both ends, cooling fins fixed to the outer periphery of the oscillating unit body, and a cooling fin provided to surround the cathode stem and output section, respectively. a circular permanent magnet; a magnetic yoke magnetically connected to the permanent magnet and disposed so as to surround the oscillating unit main body and the permanent magnet; and a yoke disposed in contact with the yoke to surround the cathode stem. A magnetron comprising a shield box and a small through hole for passing cooling air, which is provided in communication with the shield box and the yoke and is located between the magnet and the yoke opening. The magnetron is characterized in that the through hole is a hole cut and raised on the cooling fin side, and the cut and raised opening faces the permanent magnet side.

[Example of idea]

The magnetron of this invention is constructed as shown in FIG. 3, and the same parts as in the conventional example are given the same reference numerals.

That is, the oscillating unit main body 1 consists of an anode body 14 containing a resonance cavity and a cathode, a cathode stem 2, and an output section 3. Annular permanent magnets 4 and 5 are arranged on both sides of the anode body 14 so as to surround a portion of the cathode stem 2 and the output section 3, respectively. Furthermore, a plurality of plate-shaped cooling fins 10 are attached to the outer periphery of the anode body 14. A frame-shaped magnetic yoke 6 is disposed to surround the cooling fin 10, the oscillating section main body 1 , and the permanent magnets 4 and 5. As is clear from FIG. 4, a cut-and-raised hole 15, which is a transparent hole, is bored in the periphery of the upper part (the part on the side of the cathode stem 2) of this yoke 6 to serve as a ventilation hole. This cut hole 15
is formed between the magnet 4 and the opening 6a of the yoke 6, and the opening of the hole 15 is located between the permanent magnet 4 and the opening 6a of the yoke 6.
facing to the side. The cut and raised holes 15 are formed by being cut and raised toward the cooling fin 10 side. 16 is a cut piece. In addition, permanent magnets 4 and 5 are located approximately at the center of the upper and lower parts of the yoke 6, respectively.
A through hole is bored approximately corresponding to the inner diameter of the tube. or,
A filter consisting of a choke coil 7 and a feedthrough capacitor 8 is connected to the cathode stem 2, and a holeless shield box 9 is disposed to cover the filter and the cathode stem 2. The shield box 9 is box-shaped and has a cylindrical portion 9a integrally projecting therefrom, and the shield box 9 is installed so that the cylindrical portion 9a is located between the cathode stem 2 and the inner circumference of the permanent magnet 4. . In this case, a portion of the shield box 9 is in contact with the yoke 6, and the cylindrical portion 9a is closely and electrically connected to the outer periphery of a sealed metal tube 18 that is integrally bonded to the anode body 14.
Further, a through hole 13 serving as a ventilation hole is formed at the bottom of the shield box 9 in correspondence with the cut-out hole 15 provided in the yoke 6, and a portion 11a of the cooling air 11 is introduced into the shield box 9. I'm starting to do that. Note that 17 in the figure is a gasket.

In this way, a pair of ventilation holes 1 are formed in the permanent magnet 4 and the openings 6a, 6a of the square-shaped yoke located on both sides of the yoke.
5 and 15 are both constituted by a cut-out piece 16 formed diagonally so that the ventilation hole 15 near the yoke opening 6a cannot be seen through, and the opening of this ventilation hole is a permanent magnet. It faces the outer peripheral side of.

[Effect of idea]

According to this invention, the inside of the shield box 9 can be cooled by ventilation in a safe manner, and a highly reliable magnetron can be provided. That is, the cut-and-raised hole 15 with the cut-and-raised piece 16 is located between the permanent magnet 4 and the yoke opening 6a, and the opening of this hole 15 is formed to face the magnet 4, so that the cooling air 11 The part 11a collides with the permanent magnet 4,
Since it passes through the shield box 11 along the path indicated by the arrow, the cathode stem 2 and the choke coil 7 can be cooled. Furthermore, since the cut-and-raised piece 16 is present in the cut-and-raised hole 15, there is almost no fear that a wire or the like may enter from the outside, making it safer and significantly improving reliability.

In the above embodiment, the shield box 9 had a bottomed shape, but it goes without saying that the same effect can be obtained even if a bottomless shield box is used and the yoke 6 is used as a part of the shield box. stomach.

[Brief explanation of drawings]

1 and 2 are cross-sectional views showing a conventional magnetron, FIG. 3 is a cross-sectional view showing a magnetron according to an embodiment of this invention, and FIG. 4 is a yoke on the cathode stem side, which is the main part of FIG. 3. It is a perspective view of the vicinity seen from the back side. 1 ... Oscillator main body, 2... Cathode stem, 3...
Output section, 4, 5...Permanent magnet, 6...Yoke, 6
a...Yoke opening, 7...Yoke coil, 8
...Feedthrough capacitor, 9...Shield box,
10...Fin, 11...Cooling air, 13...Through hole, 14...Anode body, 15...Cut hole, 16
...A cut piece.

Claims (1)

[Claims for Utility Model Registration] An oscillating unit main body 1 with a cathode stem 2 and an output section 3 protruding from both ends, cooling fins 10 fixed to the outer periphery of the oscillating section main body, and the cathode stem and output section. annular permanent magnets 4 and 5 provided to surround the oscillator body and the permanent magnets; 6, a shield box 9 that surrounds the cathode stem and is disposed in contact with the yoke and has no ventilation holes in the side wall and lid, and the permanent magnet 4 and both openings of the square-shaped yoke located on both sides thereof. A magnetron comprising a pair of ventilation holes 15 formed in the yoke in a region between parts 6a, 6a, the pair of ventilation holes 1 formed in the yoke.
5 and 15 are both constituted by a cut-and-raised piece 16 formed diagonally so that the ventilation hole 15 cannot be seen from the yoke opening 6a, and the opening of the ventilation hole is located in the permanent magnet. A magnetron is characterized by being formed facing the outer circumferential side.