JP2579121B2 - Magnetron - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetron used for a microwave oven or the like.

[0002]

2. Description of the Related Art A conventional magnetron will be described with reference to FIG. FIG. 3 shows a cross section of a part of the magnetron.

Reference numeral 31 denotes an oscillating section main body. Oscillator main body 31
Is composed of a cylindrical anode 32, a cathode 33 located at the center of the anode 32, and the like. The anode 32 and the cathode 3
Between the three, a plurality of anode vanes 34 that divide a space surrounded by the anode 32 into a plurality and form a cavity resonator are provided. Further, annular pole pieces 35a and 35b are provided on the output side and the input side so as to cover the upper and lower openings of the anode 32, respectively. And outside the anode 32, the anode 32
A plurality of cooling fins 36 for releasing the heat generated by are provided at certain intervals in the vertical direction.

A pair of annular magnets Ma and Mb are arranged above and below the anode 32, and apply a magnetic field to a working space surrounded by the anode 32 and the cathode 33 of the oscillation section main body 31. The high-frequency signal generated by the cavity resonator is taken out by the antenna 37.

[0005] Also, metal envelopes 38a and 38b are provided continuously adjacent to the pole piece 35a on the output side. The envelopes 38a and 38b have a cylindrical shape surrounding the antenna 37 and form a transmission path for a high-frequency signal. The magnet Ma is arranged so that its inner surface contacts the outer surfaces of the envelopes 38a and 38b.

The lower side of the envelope 38a is spread in a flange shape, and the flange portion is in contact with the pole piece 35a. The ends of the envelopes 38a are bent inward to form fixed chokes. The envelope 38b is electrically connected to the waveguide via a conductive gasket 39.

A conductive gasket 39 is disposed around the envelope 38b, and an output yoke 40 is disposed outside the conductive gasket 39. Further, between the conductive gasket 39 and the output side yoke 40 and the magnet Ma, the magnetic conductive plate 4 is provided.
1 is arranged. The output side yoke 40 and the magnetic guide plate 41 form a magnetic circuit of the magnetic flux generated by the magnet Ma. An input yoke 42 is provided continuously to the output yoke 40, and the input yoke 42 extends to the position of the other magnet Mb.

In the case of the magnetron having the above-described structure, for example, the magnet Ma located on the output side is arranged so as to be in contact with the outside of the envelopes 38a and 38b, and is centered. The anode 32
In the main body composed of the cathode 33 and the like, the tip of the outer radiator 36 is press-fitted along the inner surface of the input side yoke 42, and positioning is performed by the radiator and the input side yoke.

[0009]

In the above-mentioned conventional magnetron, when the annular magnet is eccentric, a part of the inner surface comes into contact with the envelope. For this reason, heat generated at the anode and the like is transmitted to the magnet through the envelope. By the way, the magnetomotive force of the magnet has a characteristic of decreasing as the temperature rises. Therefore, when the magnetron enters the operating state and the anode temperature rises, the heat is transmitted to the magnet to reduce the magnetomotive force. As a result, the anode voltage decreases, and the input / output characteristics of the microwave oven and the like fluctuate with time.

Further, since the envelope is made of iron, when the magnet comes into contact with the envelope, the magnetic circuit of the magnet is short-circuited, and the magnetic efficiency of the magnet is reduced. For this reason, it is necessary to design a magnetic circuit in anticipation of a decrease in magnetic efficiency, and extra cost is required.

Further, the positioning of the oscillation main body is performed by a radiator. However, since the mechanical coupling between the input unit side yoke and the radiator is not always sufficient, a strong impact or the like may cause the input unit side yoke and the oscillation main body to be eccentric.

The present invention has been made to solve the above-mentioned disadvantages, and it is an object of the present invention to provide a magnetron in which a magnetomotive force and a magnetic efficiency of a magnet are prevented from lowering, or an eccentricity between an input side yoke and an oscillation body is reduced. Aim.

[0013]

SUMMARY OF THE INVENTION The present invention provides an output antenna for extracting a high-frequency signal generated from a cavity resonator, an envelope surrounding the output antenna and forming a transmission path for the high-frequency signal; A magnet that generates a magnetic field applied to the magnet, an output yoke that forms a magnetic circuit of the magnetic flux generated by the magnet and is positioned to surround the envelope, and an annular magnetic conductive plate that is in contact with the magnet. In the above, a plurality of portions of the inside portion of the magnetic plate are bent along the inside of the magnet, and other portions of the inside portion of the magnetic plate are in contact with the outer periphery of the envelope.

The outer portion of the magnetic guide plate is vertically bent all around or at a plurality of positions, and the bent portion is in contact with the inner edge of the output side yoke.

[0015]

According to the former configuration, a plurality of portions inside the annular magnetic plate are bent, and the bent portions are in contact with the inside of the magnet. Therefore, the inside of the magnet does not contact the envelope as in the past, and the heat of the anode is not easily transmitted to the magnet. Therefore, a decrease in the magnetomotive force of the magnet is suppressed. In addition, the magnetic circuit of the magnet is not short-circuited, and a decrease in magnetic efficiency can be prevented.

According to the latter configuration, a plurality of unbent portions of the inner portion of the magnetic plate contact the outer periphery of the envelope, and the entire periphery or a plurality of portions of the outer portion of the magnetic plate are vertical. And the bent portion is in contact with the inner edge of the output side yoke. For this reason, the positional relationship between the output yoke, the input yoke connected to the output yoke, and the oscillation body portion, for example, the envelope, is defined by the dimensions of the outer portion and the inner portion of the magnetic plate. Therefore, the eccentricity between the input unit side yoke and the oscillation main body can be reduced.

[0017]

An embodiment of the present invention will be described with reference to FIG. Note that FIG. 1 shows only the output portion of the magnetron, and portions corresponding to FIG. 3 are denoted by the same reference numerals.

Reference numeral 37 denotes an antenna for extracting a high-frequency signal, and a cylindrical envelope 38 surrounds the antenna 37.
a and 38b are provided continuously. Envelope 3
Reference numerals 8a and 38b form a transmission path for a high-frequency signal. A conductive gasket 39 is disposed outside the envelope 38b, and an output yoke 40 is disposed outside the conductive gasket 39. The joint between the conductive gasket 39 and the output side yoke 40 is formed with a step, and the step is fitted to each other. Also, the envelope 38
A ferromagnetic annular magnetic conductive plate 41 is provided outside b. The magnetic guide plate 41 forms a magnetic circuit for the magnetic flux of the magnet Ma together with the output side yoke 40 and the like. The magnetic guide plate 41 also positions the magnet Ma and the output side yoke 40.

Here, the configuration of the magnetic guide plate 41 will be described with reference to FIG. Since the magnetic guide plate 41 is symmetric, the center line is indicated by L, and only the left half is shown in FIG. The entire shape of the magnetic guide plate 41 is annular,
The inner edge of the magnetic guide plate 41 is processed into a gear-like unevenness, and a plurality of protrusions 22 are formed at intervals. Then, for example, every other protrusion 22A of the plurality of protrusions 22 is bent to the rear side in the figure, and as shown in FIG. 1, the bent front end 22a is in contact with the inner periphery of the magnet Ma. .

The outer edge of the magnetic guide plate 41 is bent all the way around the front side of the drawing or at a plurality of points at right angles.
b is formed. And in the bending part 22b,
As shown in FIG. 1, the inner edge of the output unit side yoke 40 is fitted. Therefore, the bent portion 22b is sandwiched between the joining surfaces between the output unit side yoke 40 and the conductive gasket 39.

Further, of the protrusions 22 of the magnetic conductive plate 41, the circular inner diameter formed at the tips of the plurality of protrusions 22B which are left unbent, for example, is slightly smaller than the outer diameter of the envelope 38b. Was selected as the envelope 38b
When pressed into the outer surface of the envelope 38b, the tips of the plurality of protrusions 22B and the outer surface of the envelope 38b come into contact with a strong force.

According to the above configuration, the heat transferred from the anode or the like to the magnet is reduced only by the inner surface of the magnet being in contact with the bent portion inside the magnetic conductive plate.
For this reason, a decrease in the magnetomotive force of the magnet due to a rise in temperature can be suppressed. In addition, a short circuit in the magnetic circuit of the magnet can be prevented, and a decrease in magnetic efficiency can be reduced.

Further, since the inside of the magnetic conductive plate is in contact with the envelope of the oscillation section main body and the outside is in contact with the output section yoke, the oscillation section main body, the output section yoke, and the input yoke connected thereto are connected. The positional relationship can be maintained stably, and the eccentricity between the oscillation section main body and the input side yoke can be reduced.

In the above-described embodiment, the inner edge of the magnetic guide plate is formed into a gear-like uneven shape, and a plurality of protrusions formed by this process are those that come into contact with the inner surface of the magnet and those that come into contact with the envelope. Are set every other one. However, such a shape is an example, and the structure can be appropriately selected as long as the inside of the magnetic conductive plate partially contacts the inner surface of the magnet and each of the envelopes.

[0025]

According to the present invention, the heat transmitted to the magnet is reduced, and the reduction in magnetomotive force and magnetic efficiency can be reduced. In addition, the eccentricity between the oscillation section main body and the yoke can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an embodiment of the present invention.

FIG. 2 is a diagram illustrating an embodiment of the present invention.

FIG. 3 is a diagram illustrating a conventional example.

[Explanation of symbols]

 22a: bent portion of the inner portion of the magnetic conductive plate 37: antenna 38a, 38b: envelope 39: conductive gasket 40: output yoke 41: magnetic conductive plate

Claims (2)

(57) [Claims] An output antenna for extracting a high-frequency signal generated from a cavity resonator, an envelope surrounding the output antenna, forming a transmission path for the high-frequency signal, and forming a vacuum envelope; A magnet for generating a magnetic field to be applied to the resonator, an output yoke forming a magnetic circuit of magnetic flux generated by the magnet and surrounding the envelope, and an annular magnetic conductive plate in contact with the magnet. In the magnetron, a plurality of portions of the inside portion of the magnetic plate are bent along the inside of the magnet, and other portions of the inside portion of the magnetic plate contact the outer periphery of the envelope, and the magnet and the envelope A magnetron characterized by performing centering. 2. An outer peripheral portion or a plurality of portions of an outer portion of the magnetic plate is bent vertically, and the bent portion contacts an inner edge of the output side yoke to center the magnetron body and the yoke. Claim 1 characterized by the following:
The magnetron described.