JPH04349332A - Magnetron - Google Patents

Abstract

PURPOSE:To provide a magnetron with improved reliability in its output part, reduced fear of breakage or cut which improves the mechanical strength by restraining increase in temp. of the whole output part, and thereby reducing concentrated thermal stress in the joining faces of a sealing ring and a ceramic cylinder. CONSTITUTION:An antenna lead 32 is made of Fe at its core part and of Cu at its surface part, while of inclination function material where the contents of Fe and Cu gradually changes on the way.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention relates to a magnetron.
In particular, it relates to improvements in the material of the antenna lead.

0002

2. Description of the Related Art The main parts of a magnetron for a microwave oven have conventionally generally been constructed as shown in FIG. In the figure, reference numeral 11 is the oscillation unit main body, 12 is the anode cylinder, 13 is a plurality of anode vanes constituting a part of the cavity resonator, 14 is a strap ring, 15 is a filament cathode, and 16
, 16 are its end shields, 17 and 18 are anode cylinders 1
2 is a pole piece fixed to the open end of 2, 19 is a cylindrical metal container, 20 is a high frequency output part, 21 is an output part ceramic cylinder, 22 is an output tip sealing ring, and 23 is hermetically sealed thereto. metal exhaust pipe, 24 is an output metal cap, 2
5 represents an output antenna lead, one end of which 2
5a is electrically connected to one of the vanes 13 and passes through a through hole 17a formed in a part of the inclined wall of the pole piece 17,
The distal end portion 25b passes through the metal container 19 and the ceramic cylinder 21 and is held in the metal exhaust pipe 23 and hermetically sealed.

Further, reference numeral 26 represents a ring-shaped permanent magnet arranged coaxially around the outer periphery of the metal container 19, 27 represents a yoke made of ferromagnetic material, 28 represents a ferromagnetic thin plate, and 29 represents a reticular conductive gasket. ing. 30 is a metal cylinder for a first harmonic choke with a small diameter that is hermetically soldered to the lower end of the ceramic cylinder 21, and 31 is a metal cylinder for a second harmonic choke that is hermetically soldered to its outer periphery. Further, it is hermetically soldered to the tip of the metal container 19, and the tip 31a serves as a gasket receiving ring for holding the inner peripheral portion of the conductive gasket 29.

Further, the inner circumferential ends of a large number of cooling fins (not shown) constituting the radiator are press-fitted onto the outer circumference of the anode cylinder 12, and the outer circumferential ends thereof are fixed to the inner surface of the yoke 27. ing.

[0005]

However, in the conventional structure described above, the temperature of the output section becomes high during high output operation. In other words, part of the heat generated in the vanes constituting the cavity resonator is
It travels through the antenna lead 25 to reach the exhaust pipe 23 and is conducted to the output tip sealing ring 22. At this time, thermal distortion occurs at the bonding surface between the sealing ring 22 and the ceramic cylinder 21, which have different thermal conductivities, causing metal fatigue and being likely to be damaged. Similarly, antenna leads are also prone to breakage. The present invention is intended to solve the above-mentioned disadvantages, and aims to provide a magnetron that suppresses temperature rise in the output section and prevents damage due to thermal distortion.

[0006]

[Means for Solving the Problems] The present invention provides an antenna lead made of a functionally graded material in which the core portion is made of Fe and the surface portion is made of Cu, and the content of Fe and Cu gradually changes along the way. It is a magnetron that has been developed.

[0007]

[Operation] According to the present invention, since the antenna lead is made of a functionally graded material whose content gradually changes, thermal conduction of thermal energy that is not converted into microwaves in the cavity resonator is suppressed. I can do it. As a result, metal fatigue at the joint surface between the sealing ring and the ceramic cylinder is prevented, and breakage of the antenna lead is suppressed, improving the reliability of the output section.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

A microwave oven magnetron that generates a fundamental wave in the 2450 MHz band to which the present invention is applied is constructed as shown in FIG. 1, and the same parts as in the conventional example (FIG. 3) are given the same reference numerals.

That is, inside the anode cylinder 12 constituting the oscillating section main body 11, a plurality of copper vanes 13 are arranged radially to form a cavity resonator. Each of the above veins 1
3, the upper and lower ends are connected every other by a pair of large and small strap rings 14, 14, respectively. A spiral filament cathode 15 is disposed along the axis of the anode cylinder 12 in the electron action space surrounded by the inner free ends of the plurality of vanes 13, and each end is connected to an end shield 16.
, 16. Furthermore, substantially funnel-shaped pole pieces 17 and 18 are fixed to both ends of the anode cylinder 12, and one pole piece 17 has a cylindrical metal container 19.
is also fixed in contact with one end of the anode cylinder 12. A second harmonic choke metal cylinder 31 having a large diameter part and a small diameter part is hermetically sealed to the upper open end of the metal container 19. In this case, the stepped portion between the large diameter portion and the small diameter portion is hermetically sealed to the open end of the metal container 19, the large diameter portion has approximately the same diameter as the metal container 19, and the output ceramic cylinder 2
1, and the gasket receiving ring 31a at the tip.
is in contact with the conductive gasket 29. Further, the small diameter portion is disposed inside the metal container 19 coaxially and extending in the vane direction. This second harmonic choke metal cylinder 31
Inside, there is a first metal cylinder 30 for a harmonic choke, which is the innermost one and has a small diameter, and a second metal cylinder 30 for a harmonic choke.
1 and the metal container 19 , and brazed to the lower end of the ceramic cylinder 21 . A retaining ring 22 is hermetically sealed to the upper end surface of the ceramic cylinder 21 . An output metal cap 24 is fixed to the side surface of the retaining ring 22, and a metal exhaust pipe 23 is hermetically sealed and held at the inner bent portion of the retaining ring 22. Further, one end of an antenna lead 32 is electrically connected to one of the vanes 13, and this antenna lead 32 passes through a through hole 17a formed in the inclined wall of the pole piece 17. It extends inside the output part 20 along the pipe axis, and the other end is an exhaust pipe 23.
It is clamped and fixed. Incidentally, this antenna lead 32 is a feature of the present invention, and will be described in detail later. Further, the outer periphery of the metal container 19 has a taper on the lower side of the inner surface.
A permanent magnet 26 in the shape of a hole is provided, and an Al radiator (not shown) in which a number of cooling fins are fitted is provided on the outer periphery of the anode cylinder 12. Surrounding these permanent magnets 26, anode cylinder 12, radiator, etc.,
A frame-like yoke 27 is provided. This frame-shaped yoke 27
A metal cylinder 3 for the second harmonic choke is placed in the center opening of the
A conductive gasket 29 is provided between the gasket receiving ring 31a, which is the tip of the conductive gasket 29. One surface of the permanent magnet 26 is in contact with the frame-shaped yoke 27 and the conductive gasket 29 via the ferromagnetic thin plate 28, and the other surface is in contact with the metal container 1.
It is in contact with the protrusion 9.

Now, to explain the antenna lead 32 in detail, as is clear from FIG. The surface portion is made of copper (Cu, but includes an alloy mainly composed of Cu), and the material is made of a functionally graded material in which the content of Fe and Cu gradually changes in the middle.

[0012] Here, the functionally graded material will be explained as follows.
Generally, when two materials A and B are joined together, the advantages of both materials can be utilized, but the disadvantage is that they are prone to bending and peeling due to the difference in coefficient of thermal expansion. However, the functionally graded material gradually changes the material quality from A to B at the intermediate interface to solve the above-mentioned problems. The details are introduced, for example, in the magazine "Industrial Materials", Vol. 38, No. 12 and No. 14 (published October 1990 and November 1990).

[0013]

[Effect of the invention] According to this invention, the antenna lead is
The core part is made of Fe and the surface part is made of Cu, and since it is made of a functionally graded material in which the content of Fe and Cu gradually changes in the middle, the temperature rise of the entire output part is suppressed, and as a result, the sealing The concentrated thermal stress at the joint surface between the attachment ring and the ceramic cylinder is reduced, and the reliability of the output section is improved. Furthermore, the risk of bending or breaking the antenna lead is alleviated, and mechanical strength is improved.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing a magnetron according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an antenna lead used in the magnetron of the present invention.

FIG. 3 is a longitudinal sectional view showing a conventional magnetron.

[Explanation of symbols]

12... Anode cylinder, 13... Vane, 20... Output part, 32...
antenna lead.

Claims (1)

[Claims] Claim 1: A plurality of vanes are arranged radially inside an anode cylinder to form a cavity resonator, one end of an antenna lead is electrically coupled to the cavity resonator, and the other end is electrically coupled to the cavity resonator. In the magnetron, in which the antenna lead extends into the output section, the antenna lead has a core made of Fe and a surface made of Cu, and is made of a functionally graded material in which the content of Fe and Cu gradually changes along the way. A magnetron featuring