JP2008010352A - Magnetron and antenna cap - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To aim at stabilization of output characteristics of a magnetron by firmly fixing its antenna cap to an exhaust tube. <P>SOLUTION: A shape of an open end face of the antenna cap 131 covering a whole of the exhaust tube 10 of the magnetron is elliptical in a state before being insertion-coupled with the exhaust tube 10. Since the antenna cap 131 is elastic, its open end face is deformed along an outer periphery of the exhaust tube 10 when it is press-fitted into the exhaust tube 10 to make an inner periphery face of the antenna cap 131 press an outer periphery face of the exhaust tube 10, so that the antenna cap 131 is firmly fixed to the exhaust tube 10 due to friction force between the inner periphery face of the antenna cap 131 and the outer periphery face of the exhaust tube 10. Since the open end face of the antenna cap 131 before insertion coupling is elliptical, pressing force working from minor axis end parts 17, 18 of an elliptical shape becomes maximum, out of pressing forces working on the outer periphery face of the exhaust tube 10. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a magnetron used in a microwave heating apparatus and an antenna cap that covers an exhaust pipe of the magnetron.

A magnetron is an electron tube that generates microwaves, and is used in microwave heating devices such as microwave ovens for cooking and thawing food. The magnetron includes an oscillating unit main body that generates a high frequency, an output unit that transmits the high frequency generated by the oscillating unit main body using an antenna, and outputs the same to the outside. A cylindrical metal container constituting a part of the output unit is hermetically joined to the output end of the oscillation unit body, and an insulating cylinder made of ceramic is hermetically joined to the output end of the metal container. An exhaust pipe is hermetically joined to the output end of the insulating cylinder, and the entire exhaust pipe is covered with an antenna cap. For example, in the magnetron of Patent Document 1, an antenna cap having a protrusion on the inner peripheral surface is press-fitted into the outer peripheral surface of an exhaust pipe having a groove on the outer peripheral surface, and the protrusion of the antenna cap is inserted into the groove of the exhaust pipe. By fitting, the antenna cap is fixed to the exhaust pipe.
JP-A-8-185806

However, the above-described conventional magnetron has the following problems.
In the magnetron, the temperature of the output part rises to about 300 ° C. during operation, but returns to room temperature when not operating. Due to the repeated heat cycle for each on / off, the fitting strength between the antenna cap and the exhaust pipe is lowered, and the antenna cap is likely to fall off or be displaced. When the antenna cap is dropped or displaced, there is a problem that the output characteristics of the magnetron become unstable.

  Further, when the antenna cap is fitted into the exhaust pipe, there is a problem that the antenna cap may be easily detached or may not be fitted depending on the inner diameter dimension of the antenna cap and the outer diameter dimension of the outer peripheral surface of the exhaust pipe.

  Moreover, in the magnetron of patent document 1, since the groove part is provided in the outer peripheral surface of the exhaust pipe, there exists a problem that the thickness of exhaust pipe itself becomes thin and the intensity | strength of an exhaust pipe falls.

  An object of the present invention is to firmly fix an antenna cap of a magnetron to an exhaust pipe and stabilize the output characteristics of the magnetron.

  A magnetron according to the present invention includes an oscillating unit main body that generates a high frequency, and an output unit that is provided on an output side of the oscillating unit main body and transmits the high frequency generated by the oscillating unit main body to the outside through an antenna. The output portion has an exhaust pipe and an antenna cap that covers the exhaust pipe, and the inner peripheral surface of the antenna cap presses the outer peripheral surface of the exhaust pipe to fix the antenna cap to the exhaust pipe. Of the pressing force acting on the outer peripheral surface of the exhaust pipe, the pressing force on the predetermined diameter end portion of the outer peripheral surface is maximized.

  Further, the present invention provides an antenna cap that is attached to an exhaust pipe of a magnetron main body and is press-fitted into the exhaust pipe. The antenna cap has elasticity and is opened in a state before being fitted into the exhaust pipe. The shape of the end face is substantially elliptical, and the inner circumference of the opening end face is shorter than the diameter of the outer circumference of the exhaust pipe.

  According to the present invention, since the antenna cap of the magnetron can be firmly fixed to the exhaust pipe, the output characteristics of the magnetron can be stabilized.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is an external view of a magnetron 100 according to the present embodiment, and FIG. 2 is a cross-sectional view schematically showing the output unit 3 side of the magnetron 100.

  The magnetron 100 includes an oscillating unit body 1 that generates a high frequency, an input unit 2 that supplies power to the oscillating unit body 1, an output unit 3 that extracts the high frequency generated by the oscillating unit body 1 to the outside, and the like.

  The oscillation part main body 1 has a metal cylinder 4 forming an anode part, and a cathode part (not shown) in which a spiral filament is disposed along the tube axis k inside the anode part. The input unit 2 includes an input side metal container 5, an insulation stem 6, and the like, and a lead wire 7 that supplies power to the cathode portion of the oscillation unit body 1 passes through the insulation stem 6.

  The output unit 3 includes an output side metal container 8, an insulating cylinder 9, an exhaust pipe 10, and the like. A cylindrical output-side metal container 8 is hermetically joined to the output end of the oscillating body 1, and an insulating cylinder 9 made of ceramic is hermetically joined to the output end of the output-side metal container 8. An exhaust pipe 10 made of soft copper is hermetically joined to the output end of the insulating cylinder 9, and the entire exhaust pipe 10 is covered with an antenna cap 13.

  As shown in FIG. 2, the exhaust pipe 10 is formed coaxially with the tube axis k, and includes a sealing portion 11 that seals the antenna 20 for taking out the high frequency generated in the oscillation portion main body 1, and the insulating cylinder 9 side. And a large diameter portion 12 having a larger outer diameter than the cylindrical body of the sealing portion 11. In order to hermetically seal the inside of the tube of the magnetron 100, the sealing portion 11 is formed by evacuating the inside of the exhaust metal tube and then chipping off with a tip-off cutter. The opening end face of the large diameter portion 12 is brazed to the end face on the output side of the insulating cylinder 9. The sealing portion 11 and the large diameter portion 12 of the exhaust pipe 10 each form part of a choke structure for preventing high frequency.

  The antenna cap 13 is made of a metal such as stainless steel that is nonmagnetic, elastic, and heat resistant, and is produced by drawing with a mold. As shown in FIG. 2, the antenna cap 13 is provided on the input side of the cylindrical portion 13a, the cylindrical portion 13a formed by opening the central portion of the bottom portion of the bottomed cylindrical body, and the cylindrical portion 13a. It is comprised from the large diameter part 13b with a larger outer diameter. The antenna cap 13 is press-fitted into the outer peripheral surface of the large-diameter portion 12 of the exhaust pipe 10, and between the inner peripheral surface of the large-diameter portion 13 b of the antenna cap 13 and the outer peripheral surface of the large-diameter portion 12 of the exhaust pipe 10. It is fixed to the exhaust pipe 10 by the frictional force acting on.

  In the present embodiment, the antenna cap 13 is described as having the large-diameter portion 13b, but it may be a bottomed cylindrical body having a small cylinder without the large-diameter portion.

  Hereinafter, specific examples of the antenna cap 13 according to the present embodiment will be described with reference to FIGS.

  First, with reference to FIG.3 and FIG.4, the antenna cap 131 which concerns on Example 1 of this embodiment is demonstrated. FIG. 3A shows the shape of the opening end surface of the large diameter portion 131b before fitting the antenna cap 131 according to the first embodiment to the exhaust pipe 10 (left figure) and the shape of the opening end surface of the exhaust pipe 10 (right). Figure). As shown in FIG. 3 (a), the inner periphery of the open end face of the large diameter portion 131b is an ellipse having a semi-minor diameter (length of the semi-minor axis) of α and a semi-major axis (length of the semi-major axis) of β. The radius r of the outer circumference of the large-diameter portion 12 of the exhaust pipe 10 has a relationship of α <r <β.

  In order to obtain the elliptical large-diameter portion 131b, as shown in FIG. 4, the cylindrical large-diameter portion is pressed from both sides using a pair of punches arranged opposite to each other in a predetermined diameter direction. That's fine. The same applies to the antenna caps of the second and third embodiments.

  FIG. 3B shows a state where the antenna cap 131 of FIG. 3A is fitted to the exhaust pipe 10. Since the antenna cap 131 has elasticity, when the antenna cap 131 is press-fitted into the exhaust pipe 10, the inner peripheral surface of the large-diameter portion 131 b is deformed into a shape (circular) along the outer peripheral surface of the large-diameter portion 12 of the exhaust pipe 10. . The antenna cap 131 is fixed to the exhaust pipe 10 by the inner peripheral surface of the large-diameter portion 131b of the antenna cap 131 pressing the outer peripheral surface of the large-diameter portion 12 of the exhaust pipe 10 and a frictional force acting between them. It will be.

  Here, before the antenna cap 131 is fitted to the exhaust pipe 10, the relationship of α <r is satisfied, so that the pressing force 17 a from the short shaft end portions 17, 18 on the inner peripheral surface of the large diameter portion 131 b. 18a is maximized, and the frictional force between the antenna cap 131 and the exhaust pipe 10 is also maximized at the short shaft end portions 17 and 18.

  According to the antenna cap 131 of the first embodiment, the shape of the opening end surface of the antenna cap 131 before being fitted to the exhaust pipe 10 is elliptical, so that the antenna cap 131 is fitted to the exhaust pipe 10. The antenna cap 131 is firmly fixed to the exhaust pipe 10 because a very large pressing force acts on the large diameter section 12 of the exhaust pipe 10 from the short shaft end portions 17 and 18 on the inner peripheral surface of the large diameter section 131b. The Rukoto. Accordingly, the fitting strength between the antenna cap 131 and the exhaust pipe 10 is improved, the pulling strength of the antenna cap 131 is improved, and the output characteristics of the magnetron 100 can be stabilized.

  Also, as shown in FIG. 4, the antenna cap 131 according to the first embodiment can be obtained simply by deforming an antenna cap having a circular opening end surface into an ellipse with a punch, and thus can be manufactured at low cost. .

  Next, the antenna cap 132 according to Example 2 of the present embodiment will be described with reference to FIGS. 5 and 6. FIG. 5A shows the shape of the open end surface of the large diameter portion 132b before fitting the antenna cap 132 according to the second embodiment to the exhaust pipe 10 (left figure), and the shape of the open end surface of the exhaust pipe 10 (right). Figure).

  As shown in FIG. 5A, the inner periphery of the opening end surface of the large-diameter portion 132b of the antenna cap 132 is elliptical, and the inner peripheral surface of the large-diameter portion 132b has two locations on the long axis end portion. Protrusions 151 and 152 projecting inward are formed. The protrusions 151 and 152 have the same shape and dimensions.

  FIG. 5B shows a state where the antenna cap 132 of FIG. 5A is fitted to the exhaust pipe 10. Since the antenna cap 132 has elasticity, when it is press-fitted into the exhaust pipe 10, the inner peripheral surface of the large-diameter portion 132 b is deformed into a shape (circular) along the outer peripheral surface of the large-diameter portion 12 of the exhaust pipe 10. . At this time, the projecting portions 151 and 152 are also deformed with spread, and the tip surfaces of the projecting portions 151 and 152 are in contact with the outer peripheral surface of the large-diameter portion 12 of the exhaust pipe 10 as shown in FIG. To do. By the pressing forces 151a and 152a from the protrusions 151 and 152, these protrusions can bite into the outer peripheral surface of the large diameter portion 12 of the exhaust pipe 10 made of soft copper, and the outer peripheral surface can be deformed.

  The protrusions 151 and 152 have an appropriate area on the tip surface (contact surface with the large-diameter portion 12) so that the outer peripheral surface of the large-diameter portion 12 of the exhaust pipe 10 is not unnecessarily damaged when the antenna cap 132 is inserted. And having an appropriate amount of protrusion. The same applies to the protrusions of Example 3 to be described later.

  In the antenna cap 131 according to the first embodiment having no protrusion, the force with which the long axis end portion of the inner peripheral surface of the large-diameter portion 131b of the antenna cap 131 presses the large-diameter portion 12 of the exhaust pipe 10 is minimized. However, in the antenna cap 132 according to the second embodiment, the protrusions 151 and 152 projecting inward are formed at the end of the long axis where the pressing force is minimum, and the protrusions 151 and 152 are the large diameter portions of the exhaust pipe 10. 12 outer peripheral surfaces were configured to be pressed.

  With such a configuration, the pressing force 17a from the short shaft end portions 17 and 18 of the large diameter portion 132b of the antenna cap 132, the pressing force 151a from the protrusions 151 and 152 formed on the long shaft end portion, Thus, the antenna cap 132 is more firmly fixed to the exhaust pipe 10. Accordingly, the fitting strength between the antenna cap 132 and the exhaust pipe 10 is improved, the pulling strength of the antenna cap 132 is improved, and the output characteristics of the magnetron 100 can be stabilized.

  In addition, by utilizing the fact that the material of the exhaust pipe 10 is annealed copper, the projections 151 and 152 of the antenna cap 132 are configured to be fitted into the exhaust pipe 10 by pressing the exhaust pipe 10. It is not necessary to provide grooves on the side for fitting with these protrusions, the strength of the exhaust pipe 10 can be ensured, and the antenna cap fitting structure can be easily realized at low cost. . The same applies to the fitting structure of Example 3 described later.

  Furthermore, when the outer peripheral side surface of the large-diameter portion 12 of the exhaust pipe 10 is tapered, the large-diameter portion 12 can be pressed by the protruding portion of the antenna cap 132, which is effective.

  Next, an antenna cap 133 according to Example 3 of the present embodiment will be described with reference to FIG. FIG. 7A shows the shape of the open end surface of the large diameter portion 133b before fitting the antenna cap 133 according to the third embodiment to the exhaust pipe 10 (left figure), and the shape of the open end surface of the exhaust pipe 10 (right). Figure).

  As shown in FIG. 7A, the inner periphery of the opening end surface of the large-diameter portion 133b of the antenna cap 133 is elliptical, and the short-axis end portion and the long-axis end portion of the inner peripheral surface of the large-diameter portion 133b. Protruding portions 161, 162, 163, and 164 projecting inward are formed at four locations between the two. The protrusions 161, 162, 163, and 164 have the same shape and dimensions. The protrusion 161 and the protrusion 163 are formed at positions that are antisymmetric with respect to the center of the ellipse. Similarly, the protrusion 162 and the protrusion 164 are formed at positions that are antisymmetric with respect to the center of the ellipse.

  FIG. 7B shows a state where the antenna cap 133 of FIG. 7A is fitted to the exhaust pipe 10. Since the antenna cap 133 has elasticity, when the antenna cap 133 is press-fitted into the exhaust pipe 10, the inner peripheral surface of the large-diameter portion 133 b is deformed into a shape (circular shape) along the outer peripheral surface of the large-diameter portion 12 of the exhaust pipe 10. . At this time, the projecting portions 161, 162, 163, and 164 are also deformed with spread, and the tip surfaces of these projecting portions contact the outer peripheral surface of the large diameter portion 12 of the exhaust pipe 10 to press the outer peripheral surface. Due to the pressing forces 161a, 162a, 163a, 164a from the protrusions 161, 162, 163, 164, these protrusions bite into the outer peripheral surface of the large diameter portion 12 of the exhaust pipe 10 made of soft copper, and the outer peripheral surface is deformed. obtain.

  According to the antenna cap 133 of the third embodiment, the protrusions 161, 162, 163, and 164 that protrude inward are formed on the inner peripheral surface of the large-diameter portion 133b at portions other than the short shaft end and the long shaft end. These protrusions are configured to be able to press the outer peripheral surface of the large diameter portion 12 of the exhaust pipe 10. As a result, the pressing forces 161a, 162a, 163a, 164a from the projections 161, 162, 163, 164 are reinforced by the pressing forces 17a, 18a from the short shaft end portions 17, 18 of the large diameter portion 133b of the antenna cap 133. As a result, the antenna cap 133 is more firmly fixed to the exhaust pipe 10. Therefore, the fitting strength between the antenna cap 133 and the exhaust pipe 10 is improved, the pull-out strength of the antenna cap 133 is improved, and the output characteristics of the magnetron 100 can be stabilized.

  In particular, the protrusion 161 and the protrusion 163 are formed at positions that are antisymmetric with respect to the center of the ellipse, so that the antenna cap 133 is fitted to the exhaust pipe 10 as shown in FIG. In this state, the pressing forces 161a and 163a by the two protrusions have the same size and have directions opposite to each other, so that the pressing forces can be balanced. The same applies to the protrusion 162 and the protrusion 164.

  The projecting portions 151 and 152 and the projecting portions 161, 162, 163, and 164 may be formed on the antenna cap by combining the second and third embodiments. Moreover, in Examples 1-3, although the shape of the opening end surface of the antenna cap was an ellipse, for example, a shape close to an ellipse, such as a straight band (a figure formed by adding a semicircle to both ends of a rectangle) It may be.

1 is an external view of a magnetron according to an embodiment of the present invention. The schematic sectional drawing by the side of the output part of the magnetron of FIG. The figure for demonstrating the antenna cap which concerns on Example 1 of this embodiment. The figure for demonstrating the method to deform | transform an antenna cap with an open end surface. The figure for demonstrating the antenna cap which concerns on Example 2 of this embodiment. Sectional drawing which shows the outline of the output part side of the magnetron which has an antenna cap of Example 2. FIG. The figure for demonstrating the antenna cap which concerns on Example 3 of this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Oscillator main part 2 Input part 3 Output part 4 Metal cylinder 5 Input side metal container 6 Insulation stem 7 Lead wire 8 Output side metal container 9 Insulation cylinder 10 Exhaust pipe 11 Sealing part 12 Large diameter parts 13, 131, 132, 133 Antenna cap 13a Cylindrical parts 13b, 131b, 132b, 133b Large diameter parts 151, 152, 161, 162, 163, 164 Protruding parts 17, 18 Short axis end part 20 Antenna 100 Magnetron

Claims (5)

An oscillating body that generates high frequencies;
An output unit provided on the output side of the oscillation unit main body, and transmitting the high frequency generated in the oscillation unit main body by an antenna and taking it out,
The output unit has an exhaust pipe and an antenna cap that covers the exhaust pipe,
The antenna cap is fixed to the exhaust pipe by pressing the outer peripheral surface of the exhaust pipe with the inner peripheral surface of the antenna cap;
Of the pressing force acting on the outer peripheral surface of the exhaust pipe, the pressing force on a predetermined diameter end portion of the outer peripheral surface is maximized. In the antenna cap attached to the exhaust pipe of the magnetron body and press-fitted into the exhaust pipe,
The antenna cap has elasticity, and the shape of the opening end surface is substantially elliptical before being fitted to the exhaust pipe, and the inner diameter of the inner periphery of the opening end surface is the outer circle of the exhaust pipe An antenna cap characterized by being shorter than the diameter.   The antenna cap according to claim 2, wherein a projecting portion protruding inward is formed at a long-axis end portion on the inner peripheral surface of the antenna cap.   The antenna cap according to claim 2, wherein a projecting portion protruding inward is formed at a portion other than the short-axis end and the long-axis end on the inner peripheral surface of the antenna cap. An oscillating body that generates high frequencies;
An output unit provided on an output side of the oscillation unit main body, and an output unit that transmits the high frequency generated by the oscillation unit main body to the outside by an antenna; and
The output part has an exhaust pipe;
A magnetron, wherein the antenna cap according to any one of claims 2 to 4 is fitted to the exhaust pipe.

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