Magnetron

Abstract

A magnetron according to the present disclosure is provided with an anode cylindrical body, a plurality of vanes, a cathode filament, an input side magnetic pole, an output side magnetic pole, and a choke structure portion. The anode cylindrical body has an input side opening portion and an output side opening portion, and is in the shape of a cylinder. The plurality of vanes are arranged radially from the central axis of the anode cylindrical body to an inner wall surface of the anode cylindrical body. The cathode filament is arranged along the central axis of the anode cylindrical body. The input side magnetic pole and the output side magnetic pole are arranged respectively in the input side opening portion and the output side opening portion. The choke structure portion is arranged inside an opening provided in the input side magnetic pole. The choke structure portion is formed seamlessly, and is arranged in such a way as to conceal a peripheral edge portion of the opening in the input side magnetic pole with respect to the central axis of the anode cylindrical body.

Description

[Technical field]

[0001] The present disclosure relates to magnetrons. [Background technology]

[0002] Patent Document 1 discloses a magnetron for microwave ovens that prevents electrical shorts between vanes and a cathode filament and deterioration of the degree of vacuum inside the tube. The magnetron described in Patent Document 1 includes a plurality of vanes arranged radially from a central axis inside an anode cylinder, and a cathode filament arranged along the central axis of the anode cylinder.

[0003] Both ends of the cathode filament are fixed to the respective end shields. A pole piece (magnetic pole) is fixed to each of the two openings of the anode cylinder. The axial distance between the end shields and the vane is dimension A, and the axial distance between the inner end of the pole piece and the vane is dimension B, and dimensions A and B are set to satisfy a specified relationship.

[0004] Patent Document 2 discloses a high-power industrial magnetron in which an approximately funnel-shaped output magnetic pole, an input magnetic pole, and a side tube are fixed to both end openings of an anode cylinder. A heat sink and a choke structure are fixed to the input magnetic pole. The heat sink dissipates heat generated in the input magnetic pole. The choke structure attenuates microwaves leaking to the cathode side. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 6-290712 [Patent Document 2] JP 2018-56078 A Summary of the Invention

[0006] Conventionally, in a high-output industrial magnetron of 2 kW or more, a heat sink and a cylindrical choke structure are fixed to the input side magnetic pole inside the core tube. In general, the magnetic pole and the cylindrical choke structure are formed by punching a ferromagnetic plate such as a cold-rolled steel plate by a press.

[0007] However, it is extremely difficult to manufacture magnetic poles with complex shapes, such as by drawing deeply or providing steps, even when using materials for deep drawing. When manufacturing magnetic poles with such complex shapes, there is a possibility that burrs or sagging will occur.

[0008] Therefore, due to the effects of burrs or sagging that occurs during press molding, or variations due to component tolerances, there is a possibility that coaxial misalignment or solder pooling may occur when the magnetic pole and the cylindrical choke structure are fixed together. This makes it difficult to manufacture to the dimensions as designed, which is one of the causes of adverse effects on characteristics, unstable operation, and short life.

[0009] An object of the present disclosure is to provide a magnetron that can suppress the occurrence of unnecessary protrusions and prevent discharge within the tube and deterioration of the vacuum degree within the tube.

[0010] The magnetron according to the present disclosure includes an anode cylinder, a plurality of vanes, a cathode filament, an input magnetic pole, an output magnetic pole, and a choke structure.

[0011] The anode cylinder has a cylindrical shape and has an input side opening and an output side opening. The vanes are arranged radially from the central axis of the anode cylinder to the inner wall surface of the anode cylinder. The cathode filament is arranged along the central axis of the anode cylinder. The input side magnetic pole and the output side magnetic pole are arranged in the input side opening and the output side opening, respectively.

[0012] The choke structure is disposed inside the aperture provided in the input pole, and is formed seamlessly and disposed so as to cover and hide the peripheral edge of the aperture in the input pole relative to the central axis of the anode cylinder.

[0013] The magnetron according to the present disclosure can prevent discharge inside the tube and deterioration of the vacuum degree inside the tube. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a cross-sectional view of a magnetron according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a cross-sectional perspective view of a main part of the magnetron according to the embodiment. [Diagram 3] FIG. 3 is a cross-sectional view of a main part of a magnetron according to a first modified example of the embodiment. [Figure 4] FIG. 4 is a cross-sectional view of a main part of a magnetron according to a second modified example of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] (The knowledge that formed the basis of this disclosure, etc.) The above problem was known at the time the inventors came up with the present disclosure. Therefore, generally, those skilled in the art designed the axial distance between the end hat and the vane and the radial distance between the end hat and the inner peripheral end of the input pole to be within a predetermined range. This prevents discharge from occurring between the end hat of the cathode part and the input pole.

[0016] In this situation, the inventors came up with the idea of ​​preventing discharge within the tube at the inner end of the input magnetic pole, inspired by the idea of ​​preventing electrons (stray electrons) emitted from the cathode filament from flowing excessively into the magnetic pole.

[0017] To realize this idea, it is necessary to suppress the coaxial misalignment when joining the input magnetic pole and the cylindrical choke structure, and to suppress the occurrence of irregularities and protrusions due to solder pools. In order to solve this problem, the inventors have come up with the subject matter of the present disclosure.

[0018] The present disclosure provides a magnetron capable of preventing the occurrence of discharge within the tube and the associated deterioration of the degree of vacuum within the tube.

[0019] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the embodiments, descriptions of known matters and redundant descriptions of identical or substantially identical configurations may be omitted.

[0020] The present embodiment will be described with reference to Figures 1 and 2. Figures 1 and 2 are a cross-sectional view and a cross-sectional perspective view of a main part of a magnetron 100 according to the present embodiment, respectively.

[0021] [composition] The magnetron 100 according to the present embodiment has an operating frequency of 2450 MHz and an output of 2 kW or more. The operating frequency is not limited to the 2450 MHz band, and may be another operating frequency, for example, 5.8 GHz band.

[0022] As shown in FIGS. 1 and 2, the magnetron 100 includes a magnetic circuit 10, a cooling circuit 20, an LC filter circuit 30, and a core tube 40.

[0023] The magnetic circuit 10 has a yoke 11, an input side permanent magnet 12, and an output side permanent magnet 13. The input side permanent magnet 12, the output side permanent magnet 13, and the cooling circuit 20 are arranged in the yoke 11. The LC filter circuit 30 is arranged in a filter case 31, and has a choke coil 32 and a capacitor 33.

[0024] The core tube 40 has an output section 41, an anode section 42, and a cathode section 43. The anode section 42 has 14 copper vanes 45 arranged on the inner wall surface of an anode cylinder 44. The vanes 45 are equally spaced and arranged radially from the central axis of the anode cylinder 44 to the inner wall surface of the anode cylinder 44.

[0025] The vanes 45 form an LC circuit. Each of the two strap rings 46 is electrically connected to every other vane 45, totaling seven vanes 45. The anode cylinder 44 has input and output openings. The input and output openings have input and output poles 47 and 48, which are approximately funnel-shaped, respectively. This forms a cavity resonator.

[0026] The input magnetic pole 47 and the output magnetic pole 48 effectively guide a magnetic field into an action space between the inner surface of the vane 45 and a cathode filament 49 described later. Each of the input magnetic pole 47 and the output magnetic pole 48 has an opening formed in the center. The central axis of the anode cylinder 44 passes through the openings of the input magnetic pole 47 and the output magnetic pole 48.

[0027] A heat sink 56 for dissipating heat and a choke structure 57 are joined by brazing to the opening peripheral portion 471 of the input side magnetic pole 47. The choke structure 57 is a cylindrical choke structure for attenuating microwaves leaking to the cathode side. The input side magnetic pole 47 is electrically connected to the heat sink 56 and the choke structure 57.

[0028] The choke structure 57 has a cylindrical portion 571 and a flange portion 572. The flange portion 572 is formed by bending so as to expand in the radial direction of the opening of the input side magnetic pole 47. The cylindrical portion 571 and the flange portion 572 are arranged at the side end portion of the input side magnetic pole 47 so as to cover the opening peripheral portion 471 of the input side magnetic pole 47 with respect to the central axis of the anode cylinder 44. The cylindrical portion 571 and the flange portion 572 are formed seamlessly.

[0029] In the present embodiment, flange portion 572 of choke structure 57 is formed by bending. However, flange portion 572 may be formed by cutting, for example, as long as it is formed seamlessly with cylindrical portion 571.

[0030] The brazing is performed using a jig. Therefore, due to the influence of the positional relationship of each part and the tolerance of the parts, the input side magnetic pole 47, the heat sink 56, and the choke structure 57 may be joined at a position displaced from the position that should be coaxial in the design. This displacement and the accumulation of brazing material at the joint may adversely affect the characteristics of the magnetron 100. For example, discharge may occur inside the tube at the inner peripheral end of the input side magnetic pole 47.

[0031] Therefore, the choke structure 57 seamlessly covers the input pole 47, thereby suppressing coaxial misalignment during joining and preventing solder accumulation at the joint. The input pole 47, heat sink 56, and choke structure 57 are arranged facing each other at the joint. The gaps between the input pole 47, heat sink 56, and choke structure 57 are interconnected, making it possible to reduce the amount of solder required for joining.

[0032] In this embodiment, the number of vanes 45 is 14. However, the number is not limited to this. For example, ten copper vanes may be arranged radially from the central axis of the anode cylinder 44 at equal intervals.

[0033] A spiral cathode filament 49 is disposed along the central axis of the anode cylinder 44 in the cathode section 43 in the electron interaction space surrounded by the inside of the vanes 45. An output side end hat 50 and an input side end hat 51 are fixed to both ends of the cathode filament 49. The output side end hat 50 and the input side end hat 51 are supported by a center lead 52 and a side lead (not shown), respectively, and are fixed to a cathode stem 53 of the input section.

[0034] The side tube 54 and the side tube 55 are fixed to the output side magnetic pole 48 and the input side magnetic pole 47, respectively. The output portion 41 and the cathode stem 53 are provided on the side tubes 54 and 55 so as to protrude from the side tubes 54 and 55, respectively.

[0035] The input side permanent magnet 12 and the output side permanent magnet 13 are coaxially arranged so as to surround the side tubes 54 and 55, respectively. Usually, a cooling block 21, which is a cooling circuit 20, is provided on the outer periphery of the anode cylinder 44. The yoke 11 is arranged so as to surround the cooling block 21, the input side permanent magnet 12, and the output side permanent magnet 13. One end of an antenna 58 is electrically connected to one of the vanes 45. The antenna 58 penetrates the output side magnetic pole 48 and extends along the tube axis of the core tube 40 to form the output section 41.

[0036] [Operation] The operation of the magnetron 100 configured as above will be described with reference to FIG.

[0037] The thermoelectrons emitted from the cathode filament 49 undergo circular motion in the hollow interaction space formed between the vanes 45 and the cathode filament 49. This causes the magnetron 100 to oscillate microwaves.

[0038] This microwave is transmitted to one of the vanes 45 and to an antenna 58 connected to one of the vanes 45, and then released into the external space. However, the conversion efficiency is not 100%. Heat is generated by electrons that could not contribute to the oscillation of the microwave. As a result, the temperature in the vicinity of the interaction space rises, which may cause unstable oscillation.

[0039] Microwaves that are not released into the external space leak into the cathode side. This causes problems such as unstable oscillation and adverse effects on the driving power supply. Such problems become more pronounced as the output increases.

[0040] As a countermeasure against these problems, in magnetrons of 2 kW or more, a heat sink 56 arranged on the input side magnetic pole 47 is used to suppress the temperature rise caused by electrons that are unable to contribute to microwave oscillation via the anode cylinder 44 and cooling block 21.

[0041] The choke structure 57 arranged on the input side magnetic pole 47 is arranged coaxially with the center lead 52 to attenuate microwaves leaking to the cathode side.

[0042] In the configuration of the magnetron 100, the cathode section 43, the input side magnetic pole 47, and the choke structure section 57 are coaxially arranged, so that electrons (stray electrons) emitted from the cathode filament 49 flow excessively into the input side magnetic pole 47. This causes an internal discharge at the inner peripheral end of the input side magnetic pole 47. As a result, the degree of vacuum inside the tube deteriorates, adversely affecting the characteristics.

[0043] In this embodiment, the inner peripheral end of the input pole 47 is covered with the choke structure 57. This makes it possible to suppress coaxial misalignment when the input pole 47 and the choke structure 57 are joined together, even if burrs or sagging occurs in the input pole 47 and the choke structure 57 during press molding. It is also possible to suppress the occurrence of irregularities and protrusions due to solder accumulation.

[0044] [effect] In this embodiment, the inner peripheral end of the input pole 47 is covered with a choke structure 57 molded integrally with the input pole 47. This makes it possible to suppress coaxial misalignment when joining the input pole 47 and the choke structure 57, and to suppress the occurrence of irregularities and protrusions due to solder accumulation. As a result, discharge inside the tube and deterioration of the vacuum inside the tube can be prevented.

[0045] [First Modification] Fig. 3 is a cross-sectional view of a main part of a first modified example of the present embodiment. As shown in Fig. 3, this modified example has an input side magnetic pole 47A, a heat sink 56A, and a choke structure 57A instead of the input side magnetic pole 47, the heat sink 56, and the choke structure 57 in the above embodiment.

[0046] In this modification, the input pole 47A is integrally formed with the choke structure 57A. This prevents the input pole 47A and the choke structure 57A from being misaligned when they are joined, and prevents the occurrence of unevenness and protrusions caused by solder pools. As a result, discharge in the tube and deterioration of the vacuum in the tube can be prevented.

[0047] [Second modified example] Fig. 4 is a cross-sectional view of a main part of a second modified example of the present embodiment. As shown in Fig. 4, this modified example has an input pole 47B, a heat sink 56B, and a choke structure 57B instead of the input pole 47, the heat sink 56, and the choke structure 57 in the above embodiment.

[0048] In this modification, the input pole 47B is seamlessly molded integrally with the choke structure 57B and the heat sink 56B. This prevents the input pole 47B and the choke structure 57B from being misaligned when they are joined, and prevents the occurrence of unevenness and protrusions caused by solder pools. As a result, discharge in the tube and deterioration of the vacuum in the tube can be prevented. [Industrial Applicability]

[0049] The present disclosure is applicable to magnetrons and microwave application devices using magnetrons, including artificial diamond generating devices, radar devices, medical devices, cooking appliances such as microwave ovens, and semiconductor manufacturing devices. [Explanation of symbols]

[0050] 100 Magnetron 10 Magnetic Circuit 11 Yoke 12 Input permanent magnet 13 Output permanent magnet 20 Cooling circuit 21 Cooling block 30 LC filter circuit 31 Filter case 32 Choke coil 33 Capacitor 40 Core Tube 41 Output section 42 Anode 43 Cathode 44 Anode cylinder 45 Bain 46 Strap ring 47, 47A, 47B Input pole 471 Opening periphery 48 Output pole 49 Cathode filament 50 Output end hat 51 Input end hat 52 Center Lead 53 Cathode stem 54, 55 side pipe 56, 56A, 56B heat sink 57, 57A, 57B Choke structure 571 Cylindrical part 572 Tsuba 58 Antenna

Claims

1. an anode cylinder having an input side opening and an output side opening and a cylindrical shape; A plurality of vanes arranged radially from a central axis of the anode cylinder to an inner wall surface of the anode cylinder; a cathode filament disposed along the central axis of the anode cylinder; an input side magnetic pole and an output side magnetic pole arranged in the input side opening and the output side opening, respectively; a choke structure disposed inside an opening provided in the input pole, a magnetron in which the choke structure and the input side magnetic pole are formed seamlessly and are arranged so as to cover and hide a peripheral portion of an opening of the input side magnetic pole relative to the central axis of the anode cylinder.

2. An anode cylinder having an input side opening and an output side opening and a cylindrical shape; A plurality of vanes arranged radially from a central axis of the anode cylinder to an inner wall surface of the anode cylinder; a cathode filament disposed along the central axis of the anode cylinder; an input side magnetic pole and an output side magnetic pole arranged in the input side opening and the output side opening, respectively; a choke structure disposed inside an opening provided in the input pole, the choke structure is formed seamlessly and is disposed so as to cover and hide the peripheral portion of the opening of the input side magnetic pole with respect to the central axis of the anode cylinder, Further comprising a heat sink joined to the input side magnetic pole, The input side magnetic pole, the heat sink, and the choke structure are disposed opposite to each other, and gaps between the input side magnetic pole, the heat sink, and the choke structure are in communication with each other.

3. An anode cylinder having an input side opening and an output side opening and a cylindrical shape; A plurality of vanes arranged radially from a central axis of the anode cylinder to an inner wall surface of the anode cylinder; a cathode filament disposed along the central axis of the anode cylinder; An input side magnetic pole and an output side magnetic pole are disposed in the input side opening and the output side opening, respectively. The magnetic poles and a choke structure disposed inside an opening formed in the input pole; a heat sink provided on the input side magnetic pole, the input side magnetic pole and the heat sink are formed seamlessly and are disposed so as to cover and hide a peripheral portion of an opening of the input side magnetic pole relative to the central axis of the anode cylinder.

4. Further comprising a heat sink provided on the input side magnetic pole, 2. The magnetron according to claim 1, wherein the input magnetic pole is seamlessly formed with the choke structure and the heat sink.

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