JP2007066673A - Magnetron for microwave oven - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetron for a microwave oven capable of preventing the falling-out of an antenna cap. <P>SOLUTION: This magnetron for a microwave oven includes: a sealing part 21 formed by chipping off an exhausting tube part for airtightly sealing the inside of the tube of the magnetron; a tubular vessel part 22 having a voluminous part 22a expanding outward from the lower end of the sealing part 21 and a tubular part 22b extending in the direction of a tube axis m and forming a part of a choke structure formed in the tube; and an insulation cylinder 19 jointed to the tubular part 2b of the tubular vessel part 22. The magnetron for a microwave oven is characterized in that the length of the sealing part 21 in the direction of the tube axis m is in the range of 8 to 10 mm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a magnetron for a microwave oven used for a microwave oven or the like.

  A magnetron for a microwave oven is an electron tube that outputs a high frequency, and is usually used as a heating source of a microwave oven for cooking or thawing food.

  Here, a conventional magnetron for a microwave oven will be described with reference to FIG. FIG. 7A is a side view, and FIG. 7B is a top view of the output unit viewed from above in FIG. 7A.

  The microwave oven magnetron includes an oscillating unit main body 71 that generates a high frequency, an input unit 72 that supplies power to the oscillating unit main body 71, an output unit 73 that extracts the high frequency generated by the oscillating unit main body 71, and the like.

  The oscillating unit main body 71 includes a metal cylinder 74 that forms an anode portion, and a cathode (not shown) is disposed inside the metal cylinder 74. The input unit 72 includes an input side metal container 75, an insulating stem 76, and the like. A lead wire 77 that supplies power to the cathode of the oscillation unit main body 71 passes through the insulating stem 76. The output unit 73 includes an output side metal container 78, an insulating cylinder 79, an exhaust metal container 80, and the like.

  The exhaust metal pipe 80 includes a sealing portion 81 and a cylindrical container portion 82. The sealing part 81 is formed by chipping off the exhaust pipe part in order to hermetically seal the inside of the magnetron pipe, and an antenna lead (not shown) for taking out the high frequency generated in the oscillation part main body 71. ) Is sealed. The cylindrical container portion 82 includes a bulging portion 82a extending outward from the lower end of the sealing portion 81, a cylindrical portion 82b extending in the tube axis m direction from the outer peripheral portion of the bulging portion 82a, and the like. The annular end portion of the cylindrical portion 82 b is brazed to the end surface of the insulating cylinder 79. Each of the sealing portion 81 and the cylindrical container portion 82 of the exhaust metal tube 80 forms part of a high-frequency blocking choke structure provided in the tube.

  An antenna cab 83 that protects the exhaust metal pipe 80 is fitted into the outer peripheral surface of the cylindrical portion 82b.

  Next, a method of hermetically sealing the inside of the magnetron tube by the sealing portion 81 will be described with reference to FIG. In FIG. 8, parts corresponding to those in FIG.

  FIG. 8 shows a state before the inside of the tube is hermetically sealed, FIG. 8 (a) is a side view, and FIG. 8 (b) is a view of the portion of the exhaust metal tube 80 from above in FIG. 8 (a). It is a top view.

  In this state, one end of the exhaust pipe portion 84 forming the sealing portion is connected to the inside of the pipe, and the other end extends upward in the figure. After exhausting the inside of the pipe through the exhaust pipe portion 84, the exhaust pipe portion 84 is chipped off at a certain length L from the enormous portion 82a of the cylindrical container portion 82 by the tip-off cutter 85, and the sealing portion 81 Is formed.

A magnetron for a microwave oven having the above-described configuration is disclosed in Patent Document 1 and the like.
JP 2004-229802 A

  In the conventional magnetron for microwave oven, the inside of the pipe is exhausted through the exhaust pipe part 84, and then the exhaust pipe part 84 is chipped off by the tip-off cutter 85 to form a sealing part 81 having a certain length. . However, when the exhaust pipe portion 84 is chipped off, the shape of the cylindrical container portion 82 may change. If the shape of the cylindrical container part 82 changes, the choke structure provided inside the cylindrical container part 82 may be deformed, and the high-frequency blocking function may be reduced.

  Therefore, the conventional magnetron for a microwave oven has a margin in the length of the sealing portion 81 so that the cylindrical container portion 82 is not deformed. For example, when the length in the tube axis m direction of the cylindrical portion 82b is about 6.6 mm, the length L of the sealing portion 81, that is, the length from the boundary with the cylindrical container portion 82 to the tip thereof is, for example, It cut | disconnects so that it may become the range of 12 mm-14 mm.

  In this case, since there is a margin in the length of the sealing portion 81, the cylindrical container portion 82 is not deformed as shown in FIG. 7B, and the cross section of the outer peripheral surface thereof is almost a perfect circle. However, when the antenna cap 83 is press-fitted into the outer peripheral surface of the cylindrical container portion 82, sufficient coupling strength is not obtained between the cylindrical container portion 82 and the antenna cap 83, and falls off due to vibration during transportation. There is a case.

  An object of the present invention is to provide a magnetron for a microwave oven that solves the above-described drawbacks and prevents the antenna cap from falling off.

  The present invention is formed by chip-off of an exhaust pipe part, and a sealing part that hermetically seals the inside of a magnetron pipe, a huge part that extends outward from the lower end of the sealing part, and a tubular shape that extends in the pipe axis direction In a magnetron for a microwave oven, comprising: a cylindrical container part having a portion and forming a part of a choke structure provided in a tube; and an insulating cylinder joined to the cylindrical part of the cylindrical container part, The length in the tube axis direction of the portion is in the range of 8 mm to 10 mm.

  In the present invention, the length of the sealing portion in the tube axis direction is shortened to 8 mm to 10 mm. For this reason, a cylindrical container part deform | transforms with the tensile stress generate | occur | produced when chipping off the exhaust pipe part, and the cross-sectional shape of the cylindrical part becomes elliptical shape. Therefore, the coupling strength between the two in the state where the antenna cap is fitted in the cylindrical container portion is increased, and the antenna cap can be prevented from falling off.

  An embodiment of the present invention will be described with reference to FIG. FIG. 1A is a side view, and FIG. 1B is a top view of the output unit viewed from above in FIG.

  The magnetron for microwave oven includes an oscillating unit main body 11 that generates a high frequency, an input unit 12 that supplies power to the oscillating unit main body 11, an output unit 13 that extracts the high frequency generated in the oscillating unit main body 11 to the outside, and the like.

  The oscillating unit main body 11 is composed of a metal cylinder 14 or the like forming an anode part, and a cathode (not shown) is disposed inside the metal cylinder 14. The input unit 12 includes an input side metal container 15 and an insulating stem 16. In addition, a lead wire 17 that supplies power to the cathode of the oscillation unit main body 11 passes through the insulating stem 16. The output unit 13 includes an output-side metal container 18, an insulating cylinder 19, an exhaust metal container 20, and the like.

  The exhaust metal pipe 20 is composed of, for example, a sealing portion 21 and a cylindrical container portion 22. The sealing part 21 and the cylindrical container part 22 are made of metal such as copper, and for example, both have an integrated structure without a joint part. The sealing part 21 is formed by chipping off the exhaust pipe part in order to hermetically seal the inside of the magnetron pipe, and an antenna lead (not shown) for taking out the high frequency generated in the oscillation part main body 11. ) Is sealed. The cylindrical container part 22 is comprised from the cylindrical part 22b extended from the outer peripheral edge part of the enormous part 22a extended outside from the lower end of the sealing part 21, and the enormous part 22a in the pipe-axis m direction etc., for example. The annular end portion of the cylindrical portion 22b is brazed to the end surface of the insulating cylinder 19, for example. Each of the sealing portion 21 and the cylindrical container portion 22 of the exhaust metal tube 20 forms part of a high-frequency blocking choke structure provided in the tube.

  In order to protect the exhaust metal tube 20, an antenna cap 23 is fitted on the outer peripheral surface of the cylindrical portion 22b, for example.

  Next, the output unit 13 of the above-described microwave magnetron will be described with reference to the cross-sectional view of FIG. In FIG. 2, parts corresponding to those in FIG.

  The output side metal container 18 has a double cylindrical structure of an outer cylindrical portion 18a and an inner cylindrical portion 18b. For example, the end surface of the insulating cylinder 19 is provided on a flat surface 18c provided between the outer cylindrical portion 18a and the inner cylindrical portion 18b. It is brazed.

  The exhaust metal pipe 20 is provided with, for example, a cylindrical projecting portion 22 c extending substantially in parallel with the cylindrical portion 22 b on the extension of the sealing portion 21. The space A surrounded by the sealing portion 21 and the protruding portion 22c and the annular space B sandwiched between the cylindrical portion 22b and the protruding portion 22c form a choke structure that prevents unnecessary harmonics. Further, the annular space C sandwiched between the outer cylindrical portion 18a and the inner cylindrical portion 18b of the output side metal container 18 also forms a choke structure that prevents unnecessary harmonics. The antenna lead 24 passes through the output side metal container 18, the insulating cylinder 19, and the exhaust metal pipe 20 and is sealed by the sealing portion 21.

  In the above-described magnetron for microwave oven, the inside of the pipe is exhausted through the exhaust pipe section connected to the inside of the pipe, and then the exhaust pipe section is cut off at the tip-off to form a sealing portion 21 that hermetically seals the inside of the pipe.

  Here, the shape of the exhaust metal pipe 20 formed by tip-off of the exhaust pipe portion will be described with reference to FIG. 3A is a side view, and FIG. 3B is a top view of the exhaust metal pipe 20 as viewed from above in FIG. 3A. In FIG. 3, the same reference numerals are given to the portions corresponding to FIG.

  As shown in FIG. 3A, when the length l of the cylindrical portion 22b of the cylindrical container portion 22, that is, the so-called side choke height is 6.6 mm, the length c of the sealing portion 21, the so-called chip-off dimension. Is shortened to be in the range of 8 mm to 10 mm. In this case, since the length c of the sealing part 21 is short, when the exhaust pipe part is chipped off, the cylindrical part 22b is deformed into an elliptical shape. For example, as shown in FIG. 3B, when the diameter of the swollen portion of the cylindrical portion 22b is a, and the diameter orthogonal to this is b, the difference (ab) between the two is calculated for the cylindrical portion 22b. Assuming the amount of deformation, the amount of deformation is, for example, in the range of 0.2 to 0.4 mm. With the deformation of the cylindrical portion 22b, the pullout strength when the antenna cab 23 is fitted is increased to 150N to 170N, and the holding strength of the antenna cap 24 is improved.

  Here, for example, when the length l of the cylindrical container portion 22 is 6.6 mm, the relationship between the length l of the cylindrical container portion 22, the deformation amount of the cylindrical portion 22b, and the pull-out strength of the antenna cap 23 is illustrated. 4 to 6.

  FIG. 4 shows the relationship between the length c (horizontal axis: mm) of the sealing portion 21 and the deformation amount (vertical axis: mm) of the cylindrical portion 22b. FIG. 5 shows the relationship between the deformation amount of the cylindrical portion 22b (horizontal axis: mm) and the pullout strength (vertical axis: N) of the antenna cap. FIG. 6 shows the relationship between the length c (horizontal axis: mm) of the sealing portion 21 and the pullout strength (vertical axis: N) of the antenna cap.

  As shown by the characteristic P in FIG. 4, the amount of deformation of the cylindrical portion 22b increases as the length c of the sealing portion 21 decreases. Further, as shown by the characteristic Q in FIG. 5, the pull-out strength of the antenna cap increases as the deformation amount of the cylindrical portion 22b increases. And as shown to the characteristic R of FIG. 6, the extraction strength of an antenna cap becomes high, so that the length c of the sealing part 21 is short.

  The conventional magnetron for a microwave oven has a margin in the length of the sealing portion 21 so that the cylindrical portion 22b is not deformed, and the length of the sealing portion 21 is set to, for example, a symbol S (12 mm to 14 mm) in FIG. The range is set. In this case, the deformation amount of the cylindrical portion 22b is about 0 to 0.1 mm, and the pullout strength is about 140N.

  In the present invention, the length of the sealing portion 21 is set in the range of the symbol T in FIG. 6 (8 mm to 10 mm). In this case, the pullout strength is as large as 150N to 180N.

  If the length of the sealing portion is smaller than 8 mm, the deformation amount of the cylindrical portion becomes as large as 0.5 mm or more, and it is difficult to fit the antenna cap, which is not suitable for mass production. Therefore, the length of the sealing part is desirably 8 mm or more.

  Further, in the case of the invention, the cylindrical portion is slightly deformed, but the effect of suppressing harmonics is not lowered, and no practical problem occurs.

1 is a schematic structural diagram for explaining an embodiment of the present invention. It is sectional drawing which extracted the output part of this invention. It is a schematic structure figure explaining the amount of deformation of the cylindrical part concerning the present invention. It is a characteristic view which shows the relationship between the length of the sealing part which concerns on this invention, and the deformation amount of a cylindrical part. It is a characteristic view which shows the relationship between the deformation amount of the cylindrical part which concerns on this invention, and the extraction strength of an antenna cap. It is a characteristic view which shows the relationship between the length of the sealing part which concerns on this invention, and the extraction strength of an antenna cap. It is a general | schematic structural diagram for demonstrating a prior art example. FIG. 3 is a schematic structural diagram for explaining a tip-off method of an exhaust pipe portion.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Oscillator main part 12 ... Input part 13 ... Output part 14 ... Metal cylinder 15 ... Input side metal container 16 ... Insulation stem 17 ... Lead wire 18 ... Output side metal container 19 ... Insulation cylinder 20 ... Exhaust metal pipe 21 ... Sealing Stop part 22 ... cylindrical container part 22a ... enormous part 22b ... cylindrical part 23 ... antenna cap m ... tube axis

Claims (3)

  The exhaust pipe part is formed by chip-off, and has a sealing part that hermetically seals the inside of the magnetron pipe, a huge part that extends outward from the lower end of the sealing part, and a cylindrical part that extends in the pipe axis direction In the magnetron for a microwave oven, comprising: a cylindrical container part forming a part of a choke structure provided in the pipe; and an insulating cylinder joined to the cylindrical part of the cylindrical container part. A magnetron for a microwave oven characterized by having a length in the range of 8 mm to 10 mm.   The magnetron for a microwave oven according to claim 1, wherein the sealing part and the cylindrical container part are made of copper and integrally formed.   The magnetron for a microwave oven according to claim 1 or 2, wherein a length of the cylindrical portion constituting the cylindrical container portion in the tube axis direction is about 6.6 mm.

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