KR0139342Y1 - Output structure of magnetron - Google Patents

Abstract

The present invention relates to an output structure of a magnetron that blocks harmonic components and noise leaked through an output portion, and rotates by deflecting the filament 17 emitting hot electrons and the electrons emitted from the filament 17. Permanent magnets 41 and 43 for generating magnetic fluxes to maintain the magnetic flux, first and second magnetic pole pieces 33 and 35 for forming magnetic paths for inducing magnetic fluxes generated from the permanent magnets 41 and 43, and the filaments An anode cylinder 13 in which a plurality of vanes 15 are arranged to surround the outside 17 to generate microwaves, and a coaxial line 49 for inducing microwaves generated by the anode cylinder 13 to the antenna 47. ), An antenna cap 51 for inducing microwaves induced through the coaxial line 49, and welding to the upper portion of the first magnetic pole piece 33 to seal the inside of the anode body 13 with a vacuum. Upper metal pipe 37, the upper metal pipe 37 and the inner It characterized in that the insulating ring 45 is bonded to the upper portion of the upper metal pipe 37 to insulate the tenacap 51.

Description

Magnetron Output Structure

1 is a longitudinal sectional view of a conventional magnetron output unit.

2 is an enlarged cross-sectional view of an output upper metal pipe according to the related art.

3 is a longitudinal sectional view of a magnetron according to an embodiment of the present invention.

Figure 4 is an enlarged cross-sectional view of the output upper metal pipe applied to the present invention.

* Explanation of symbols for main parts of the drawings

13: bipolar cylinder 15: vane

17: filament 19,21: upper and lower end hat

23: external lead wire 25: center lead wire

27: Insulation ceramic 29,31: External connection terminal

33,35: first and second magnetic pole pieces 37,39: upper and lower metal pipes

41,43: permanent magnet 45: insulating ring

47: antenna 49: coaxial line

51: antenna cap 53,55: yoke

57: heat sink

The present invention relates to a magnetron used in a microwave heating apparatus such as a microwave oven, and more particularly, to an output structure of a magnetron that blocks harmonic components and noise leaked through an output unit.

In general, the output structure of the magnetron according to the related art is, as shown in FIGS. 1 and 2, the upper metal pipe 3 having the magnetic pole pieces 2 fitted on one side of the anode body 1 is fixed, At the upper opening end of the upper metal pipe 3, a cylindrical insulating ring 4 made of ceramic constituting the output part is hermetically welded to one end of the upper metal pipe 3.

An antenna 5 made of copper is fixed to an upper end of the insulating ring 4, and a high frequency generated from the anode cylinder 1 is located near the inner center of the antenna 5. A coaxial line 6 derived from one vane, not shown to guide it, extends axially through the through-hole of the pole piece 2 so that the end of the coaxial line 6 is moved by the antenna 5. It is fixed.

The outer surface of the antenna 5 is also covered with an antenna cap 7 for inducing microwaves induced through the coaxial line 6.

By the way, in the magnetron configured as described above, when 4KV of power is applied to both ends of the filament (not shown), the fundamental frequency of 2450MHz band is generated in the anode cylinder 1, and at the same time, it is an integer multiple of the fundamental wave (2450MHz). A second harmonic (4900 MHz) to a seventh harmonic (7350 MHz) component having a frequency is generated.

Microwave energy of the fundamental wave and harmonic (noise) component generated in the anode cylinder 1 is radiated to the output of the magnetron while conducting through the coaxial line 6 and is transmitted to the cavity of the microwave oven through the waveguide, so that it is unnecessary in the cavity. Noise exists.

The noise present in the cavity leaks to the outside through a door of a microwave oven, which causes not only wireless communication failure but also harms a human body.

Accordingly, the present invention is made to solve the above problems, the object of the present invention is to form a choke structure of the upper metal tube bonded to the output insulation ring to shield the harmonic components leaking to the outside through the output portion The present invention provides a structure of an output unit of a magnetron that can not only prevent wireless communication obstacles but also simplify the structure.

Another object of the present invention is to provide a magnetron output part structure capable of supplying stable microwave energy by shielding microwaves flowing back from microwave waveguides by making the oscillation frequency band of microwaves generated in the anode cylinder close to 2450 MHz.

In order to achieve the above object, the output structure of the magnetron according to the present invention is a filament emitting hot electrons, a permanent magnet generating magnetic flux to maintain rotational motion by deflecting electrons emitted from the filament, and generated in the permanent magnet. First and second magnetic pole pieces forming magnetic paths to induce a magnetic flux, a plurality of vanes arranged to generate microwaves by surrounding the filament from the outside, and microwaves generated by the anode cylinders to guide the antenna A coaxial line, an antenna cap for inducing microwaves induced through the coaxial line, an upper metal tube welded and fixed to an upper portion of the first magnetic pole piece to seal the inside of the anode cylinder with a vacuum, the upper metal tube and the antenna cap Characterized in that the insulating ring bonded to the upper portion of the upper metal pipe to insulate the The.

Hereinafter, with reference to the accompanying drawings an embodiment of the present invention will be described in detail.

As shown in FIG. 3, a plurality of (even) vanes 15 forming a plurality of resonant cavities so as to attenuate harmonic components leaking to the outside inside the anode cylinder 13 formed in a cylindrical shape by a copper plate or the like. It is arrange | positioned at equal intervals toward this axial direction, and an anode part is comprised by these anode cylinder 13 and the vane 15. As shown in FIG.

In addition, the inner and outer pressure equalizing rings 15a and 15b are disposed to filter the vanes 15 so as to obtain a constant resonance frequency by varying capacitances in the upper and lower portions near the tip end side of the vanes 15, respectively. Near the central axis of the anode cylinder 13, a working space 14 is formed by the tip of the plurality of vanes 15, and in the working space 14, a thorium-tungsten or the like is spiraled to radiate hot electrons. The filament 17 wound by the coil is arranged coaxially with the anode cylinder 13.

Upper and lower end hats 19 and 21 are fixed to both ends of the filament 17 to prevent radiation of hot electrons that do not contribute to oscillation in the central axis direction. The outer lead wire 23 made of molybdenum is welded and fixed to the bottom surface, and the center lead wire 25 made of molybdenum as a central support body made of molybdenum is formed at the center of the lower end hat 21 through the through hole formed at the center thereof. Welding is fixed to the lower end of the end hat 19.

Here, the center lead wire 25 is bent at two locations in the middle portion while penetrating the lower end hat 21 and the filament 17 in a non-contact manner, and the outer and center lead wires 23 and 25 are magnetrons. The filament 17 is electrically connected to the first and second external connection terminals 29 and 31 which are connected to a power supply terminal (not shown) through a through hole formed in the insulating ceramic 27 supporting and fixing the cathode of (4). To supply the operating current.

In addition, the first and the funnel-shaped magnetic bodies that form magnetic paths to uniformly form magnetic flux in the working space 14 formed by the filaments 17 and the vanes 15 at both openings of the anode cylinder 13. The second magnetic pole pieces 33 and 35 are seated at positions notched inside both ends of the positive electrode body 13, bent and fixed at the outer edges of the remaining both ends, and are hermetically weld-bonded.

Above and below the first and second magnetic pole pieces 33 and 35, upper and lower metal pipes 37 and 39 for sealing the inside of the anode cylinder 13 with vacuum are provided in the first and second magnetic pole pieces 33. And 35 are hermetically welded to the intermediate portion of the anode 35 or both opening portions of the anode cylinder 13, respectively.

In addition, ring-shaped permanent magnets 41 and 43 are provided on the outer and upper surfaces of the upper and lower metal pipes 37 and 39 so as to maintain a constant magnetic field distribution in the anode cylinder 13. It is disposed at a predetermined distance to the left and right, and the upper opening end of the upper metal tube 37 constituting the output of the magnetron 4 is made of a ceramic to insulate the upper metal tube 37 and the antenna to be described later. The cylindrical output side insulating ring 45 is joined.

In the drawing, an antenna 47 made of copper is joined to the upper end portion of the insulating ring 45, and the vane is formed so as to output a high frequency oscillated in the resonance cavity near the inner center of the antenna 47. 15) The end of the coaxial line 49 is fixed by the antenna 47 while the coaxial line 49 derived from one extends axially through the through hole of the first magnetic pole piece 33.

In addition, the antenna cap that protects the welded portion of the antenna 47 on the outer surface of the antenna 47 as well as prevents sparking due to electric field concentration and acts as a high frequency antenna and draws a high frequency output to the outside ( 51) is covered.

In addition, the outer circumferential surface of the positive electrode body 13 is provided with yokes 53 and 55 for determining the amount of magnetic elements in the positive electrode body 13 to connect the magnetic flux being returned, and the yoke 53 and 55 Inside the plurality of aluminum heat sink 57 extending in the radial direction of the tube is fitted by the clamp member (55a) fixed to the yoke (53, 55) to form a rule together with the permanent magnet (41, 43) It is covered by yokes 53 and 55.

On the other hand, the upper metal tube 37 is shown in Figure 4 to prevent leakage of the second to seventh harmonic components corresponding to the integer multiple of the 2450MHz band fundamental frequency generated in the anode cylinder 13 to the outside through the output unit As described above, a choke structure having a depth T and a hole diameter D is formed at an upper portion thereof, and the length of the depth T is equal to or smaller than or equal to the hole diameter D. Have

In addition, the depth T of the upper metal pipe 37 is less than 5mm in length, and its direction is designed to face inward or outward with the anode cylinder 13.

Hereinafter, the effect of the output structure of the magnetron configured as described above will be described.

First, when power is applied through the first and second external connection terminals 29 and 31, the first external connection terminal 20 → the center lead wire 25 → the upper end hat 19 → the filament 17 → a closed circuit is formed by the lower end head 21 → the external lead wire 23 → the second external connection terminal 31 so that an operating current is supplied to the filament 17 and heated.

When the filament 17 is heated to a high temperature state, hot electrons start to be emitted from the filament 17, and the released hot electrons move toward the vane 15 at an initial speed due to the high pressure applied to the vane 15. Proceed.

While the hot electrons emitted from the filament 17 travel toward the vanes 15, the electrons are deflected by the magnetic flux generated in the working space 14 by the first and second magnetic pole pieces 33 and 35. Due to the deflection of the electrons, electrons repeatedly form a group of electrons, and the vane 15 repeatedly moves to a high potential, and the vane 15 has a 2450 MHz band (fundamental wave) corresponding to the speed at which the electron group rotates. Generate microwaves.

Thus, the microwave energy generated in the vanes 15 is conducted through the coaxial line 49, radiated to the output of the magnetron and transmitted through the waveguide into the cavity of the microwave oven.

At this time, even if the oscillation is ideally generated in the anode cylinder 13, various microwaves are generated by temperature increase or reflection wave or impedance defects of the microwave and the magnetron, and most of the microwaves generated in the anode cylinder 13 are coaxial lines. Conductive through (49) it contains many harmonics.

In order to shield the harmonic components generated in the anode cylinder 13, the radio wave must be made on the coaxial line 49, and in the present invention, the upper metal pipe 37 does not contact the coaxial line 49 and maintains a constant interval. The choke structure is formed between the coaxial line 49 and the upper metal pipe 37 because of the choke structure.

The choke structure formed between the coaxial line 49 and the upper metal pipe 37 shields low and high frequencies other than 2450 MHz oscillated from the magnetron, effectively shielding harmonic noise.

In addition, in the case of noise coming from the outside, the microwave received from the antenna cap 51 is transmitted to the coaxial line 49 and flows into the anode cylinder 13. In the present design, the microwave coming from the upper metal pipe 37 is also a choke structure. Since the shielding prevents the elements causing adverse effects on the anode cylinder 13 in advance, a stable resonance frequency is obtained at the vane 15.

When the reverse microwave transmitted to the anode cylinder 13 is less, the heat generated from the anode cylinder 13 is reduced, and as a result, the heat generated from the magnetron can be reduced, so that less heat is radiated from the heat sink 57. The shape of the magnetron can be reduced.

On the other hand, the energy attenuated in the magnetron (S) and the cutoff frequency (fc) is as shown in the following (1), (2), the hole diameter (D) and the height (T) of the upper metal pipe 37 Will change accordingly.

S = 32 (T / D) dB ... (1)

fc = (2.7 x 109) / D Hz ...... (2)

Therefore, in the conventional upper metal tube 3, as shown in FIG. 2, since the hole diameter D is larger than the height T, the attenuation of energy S is made small and the cutoff frequency fc is low.

On the contrary, the upper metal pipe 37 of the present invention has a larger attenuation of energy S than the conventional one because the hole diameter D is equal to or smaller than the height T, as shown in FIG. ), It is possible to shield harmonics that must shield very high frequencies more effectively than in the prior art.

According to the output structure of the magnetron according to the present invention as described above, by forming the choke structure of the upper metal pipe bonded to the output insulation ring to shield the harmonic components leaking to the outside through the output portion, radio communication failure In addition, the structure is simple and can be miniaturized, and it is possible to supply stable microwave energy by shielding microwaves flowing back from the microwave waveguide by making the oscillation frequency band of the microwave close to 2450 MHz in the anode cylinder. Excellent effect.

Claims (8)

Filaments 17 for emitting hot electrons, permanent magnets 41 and 43 for generating magnetic flux so as to maintain rotational motion by deflecting electrons emitted from the filaments 17, and generated in the permanent magnets 41 and 43 First and second magnetic pole pieces 33 and 35 forming magnetic paths to induce a magnetic flux, and a plurality of vanes 15 arranged to surround the filament 17 from outside to generate microwaves 13 ), A coaxial line 49 for guiding the microwaves generated by the anode cylinder 13 to the antenna 47, an antenna cap 51 for guiding the microwaves induced through the coaxial line 49, and the To insulate the upper metal tube 37 and the upper metal tube 37 and the antenna cap 51 welded to the upper portion of the first magnetic pole piece 33 to seal the inside of the anode cylinder 13 with a vacuum. E, characterized in that consisting of an insulating ring 45 bonded to the upper portion of the upper metal pipe (37) Output structure of four torch. 2. The output structure of the magnetron according to claim 1, wherein the upper metal pipe (37) forms a choke structure to shield harmonic components leaking to the outside through the output portion. The output structure of the magnetron according to claim 1, wherein the upper metal pipe (37) has a length (T) equal to a hole diameter (D). 2. The output structure of the magnetron according to claim 1, wherein the upper metal pipe (37) has a length (T) of more than a hole diameter (D). The output structure of the magnetron according to claim 1, wherein the upper metal pipe (37) has a length (T) less than or equal to the hole diameter (D). The output structure of the magnetron according to claim 1, wherein the upper metal pipe (37) has a length (T) of 5 mm or less. 2. The output structure of the magnetron according to claim 1, wherein the upper metal pipe (37) faces inwardly with the anode cylinder (13). 2. The output structure of the magnetron according to claim 1, wherein the upper metal pipe (37) is directed toward the outside where the anode cylinder (13) is located.