JPH05290748A - Magnetron - Google Patents

Abstract

PURPOSE:To eliminate the need for such troublesome work as to join a shield cylinder to the cylindrical part of a filter case in a ring-shaped permanent magnet and at the same time to improve the exciting efficiency of a magnetron. CONSTITUTION:A shield cylinder 20 is abutted at its cylindrical part 20a against the peripheral 'face of a metallic tube 5, and then a flange part 20b projected in the shape of a flange from the end of an opening in the cylindrical part 20a is insetted into a ring-shaped recessed groove 23 formed in a frame-shaped yoke 21. around its communicating hole 22. A short and small kind of shield cylinder may suffice the shield cylinder in this case, and consequently there is also no need for the shield cylinder to be overlapped with the cylindrical part of a filter case. There is also no danger of damaging a ring-shaped permanent magnet caused by a leakage electromagnetic-wave transmitted through a stem to act on the permanent magnet. The inside diameters of both the permanent magnet and the communicating hole for the stem of the frame-shaped yoke can thus be reduced to improve the exciting efficiency of a magnetron.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetron device used for high frequency heating equipment such as a microwave oven.

[0002]

2. Description of the Related Art Generally, a magnetron device incorporated in a microwave oven is constructed as shown in FIG. The magnetron 1 has an anode cylinder 3 that coaxially surrounds the cathode 2.
A first magnetic pole piece 4 provided at one open end of the anode cylinder 3, a first metal tube 5 covering the magnetic pole piece 4, a cathode terminal lead-out stem 6, and an anode cylinder. A second magnetic pole piece 7 provided at the other open end of the body 3, a second metal tube 8 that covers the magnetic pole piece 7, and a projecting installation on the metal tube 8 via an insulating ring 9 made of ceramics. And an electromagnetic wave emission terminal 10.

A first ferrite member stacked on the outer end face of the first magnetic pole piece 4 so as to surround the first metal tube 5.
The ring-shaped permanent magnet 11 has a magnetic pole, one of which is magnetically coupled to the first magnetic pole piece 4. In addition, the second annular permanent magnet 12 made of ferrite stacked on the outer end surface of the second magnetic pole piece 7 so as to surround the second metal tube 8 has one magnetic pole of the second magnetic pole piece 7. Is magnetically coupled to. The frame yoke 13 for magnetically coupling the other magnetic poles of the first and second annular permanent magnets 11 and 12 to each other is
The one end has a through hole for inserting the stem 6. On the other hand, the first metal tube 5 and the first annular permanent magnet 11
The metal shield cylinder body 14 having a cylinder portion between and has a flange portion sandwiched by the first magnetic pole piece 4 and the first annular permanent magnet 11.

A large number of heat radiation fins 15 are attached to the outer peripheral surface of the anode cylinder 3 in multiple stages, and a metal filter is provided on the outer surface of one end of the frame yoke 13 to prevent leakage electromagnetic waves from leaking out of the apparatus. A case 16 is attached. The filter case 16 has a tubular portion 16a, and the tubular portion 16a overlaps the tubular portion of the shield tubular body 14. A through-type capacitor 17 is attached to the side wall of the filter case 16, and one end of a choke coil 19 is connected to the cathode terminal 18 of the stem 6 that is recessed in the filter case 16. The choke coil 19 has its other end connected to the through electrode of the capacitor 17 so as to form an LC filter circuit for preventing leakage electromagnetic waves.

In the magnetron device thus constructed, the electromagnetic interference caused by the leakage of the electromagnetic wave leaking to the stem 6 side to the outside of the device causes the LC filter circuit by the choke coil 19 and the capacitor 17, the filter case 16 and the shield cylinder 14. It can be prevented by the shielding effect by. Further, since the stem 6 is made of ceramics, there is a risk of damaging the permanent magnet 11 if the electromagnetic wave transmitted through the stem 6 acts on the first annular permanent magnet 11 made of ferrite. This is eliminated by the shielding action of the cylindrical portion and the shield cylinder 14 connected to this portion.

[0006]

However, not only the relatively long shield cylinder 14 is required, but also the cylindrical portion 16a provided in the filter case 16 is shielded in the first annular permanent magnet 11. It must be superposed on the cylinder 14, which is a troublesome assembly work. Further, in order to adopt such a superposition structure, the inner diameter of the permanent magnet 11 and the diameter of the stem through hole of the frame yoke 13 must be set sufficiently large, which causes a considerable decrease in the excitation efficiency. There was a problem.

[0007]

In the magnetron device according to the present invention, a stem for leading out the cathode terminal is projected on a metal tube covering the first magnetic pole piece provided at one open end of the anode cylinder. A magnetron, and a ferrite annular permanent magnet that is stacked on the outer end face of the first magnetic pole piece so as to surround the metal tube, and one magnetic pole is magnetically coupled to the first magnetic pole piece, The other magnetic pole of the permanent magnet is magnetically coupled to the second magnetic pole piece of the magnetron, and a frame-shaped yoke having a through hole at one end for inserting the metal tube, and an outer end surface of the permanent magnet. It is provided with a metal-made shield cylinder provided above. The shield tubular body has a tubular portion that is in contact with the outer peripheral surface of the metal tube, and a flange portion that projects from the open end of the tubular portion in a brim shape,
The flange portion is configured to be recessed in an annular groove provided around the through hole of the frame yoke.

[0008]

The shield cylinder in the magnetron device thus constructed need not be shorter than the shield cylinder of the conventional device, and it does not need to be overlapped with the cylinder of the filter case. Moreover, there is no risk that the electromagnetic wave transmitted through the stem acts on the first annular permanent magnet and damages the permanent magnet, and also the inner diameter of the first annular permanent magnet and the stem through hole of the frame yoke. Both the inner diameter can be set small, and the excitation efficiency can be increased accordingly.

[0009]

The present invention will be described below with reference to the illustrated embodiments. The configuration shown in FIG. 1 differs from the conventional configuration shown in FIG. 4 in that a metallic shield cylinder 20 has a relatively short tubular portion 20a, and this tubular portion 20a is the magnetron 1
Point of contact with the outer peripheral surface of the first metal pipe 5, the frame-shaped yoke 21 has an annular groove 23 around the through hole 22, and the groove 23 has a shield. The point where the flange portion 20b of the tubular body 20 is recessed, the first annular permanent magnet 24 made of ferrite, and the stem through hole 22 of the frame yoke 21.
However, both have a relatively small inner diameter, and the filter case 25 does not have a cylindrical portion, and there is no fundamental difference in other configurations.

As shown in FIG. 2, the first metal tube 5 has an outer diameter of A, and the tubular portion 20a of the shield tubular body 20 is in close contact with the outer peripheral surface of the metal tube 5. For this reason, it is not necessary to provide the filter case 25 with the above-mentioned tubular portion or to superpose this tubular portion on the shield tubular body. Further, there is no risk that the electromagnetic wave transmitted through the stem 6 acts on the annular permanent magnet 24 to damage the permanent magnet. Further, since the diameter B of the through hole 22 of the frame yoke 21 and the inner diameter C of the first annular permanent magnet 24 can both be set to 120% or less of the outer diameter A, the excitation efficiency can be improved.

The present invention can also be applied to a magnetron device having no filter case 25. in this case,
The entire device is housed in a single shield case together with an electric fan for generating air-cooled airflow, and only the electromagnetic wave emission terminal 10 projects from the shield case. Although the leaked electromagnetic wave transmitted through the stem 6 may diffuse and act on the annular permanent magnet 24, the leaked electromagnetic wave immediately after passing through the stem does not act on the permanent magnet 24.
There is no danger of damaging 4.

[0012]

As described above, according to the present invention, the troublesome work of superposing the tubular portion of the filter case on the tubular portion of the shield tubular body is unnecessary, and the electromagnetic wave transmitted through the stem is annular permanent magnet. There is no danger of damaging the permanent magnet by acting on the magnet, and the inner diameter of the annular permanent magnet and the inner diameter of the stem through hole of the frame yoke can both be set small, so that the excitation efficiency can be increased accordingly. it can.

[Brief description of drawings]

FIG. 1 is a partially cutaway side view of a magnetron device embodying the present invention.

FIG. 2 is an enlarged sectional view of a main part of the device.

FIG. 3 is a partially cutaway side view of a conventional magnetron device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetron 3 Anode cylinder 5 1st metal tube 6 Stem 20 Shield cylinder 21 Frame yoke 22 Stem through hole 23 Recessed groove 24 First annular permanent magnet

Claims (1)

[Claims] 1. A first electrode provided at one open end of an anode cylinder.
A metal tube covering the pole piece of the
The relationship between the magnetron and the metal tube
The first magnetic pole piece is stacked on the outer end face of the first magnetic pole piece, and
Made of ferrite with poles magnetically coupled to the first pole piece
The ring-shaped permanent magnet and the other magnetic pole of the permanent magnet.
When magnetically coupled to the second pole piece of the magnetron
Has a through hole at one end for inserting the metal tube.
Frame-shaped yoke and gold provided on the outer end surface of the permanent magnet
A metal-made shield tube body is provided, and the shield tube
The body consists of a tubular part that is in contact with the outer peripheral surface of the metal tube, and the tubular part.
The flange part protruding like a collar from one open end of the part
Has the flange portion around the through hole of the frame yoke
It is characterized by being immersed in an annular groove provided in the
Magnetron device.