JP2017111955A - Magnetron - Google Patents

Abstract

A magnetron is provided that has a performance equal to or better than that of a conventional one but uses less copper.
An anode cylinder 12 has a double structure including an inner peripheral portion 12A and an outer peripheral portion 12B, and an inner inner peripheral portion 12A is not made of nonmagnetic oxygen-free copper but compared with nonmagnetic oxygen-free copper. In addition, graphene is generally used which has high strength, electrical conductivity, melting point, and thermoelectricity, and extremely little outgassing at high temperatures. Thereby, it is possible to realize a magnetron 1 that has a performance equal to or better than that of a conventional magnetron and that uses a reduced amount of copper.
[Selection] Figure 2

Description

  The present invention relates to a magnetron, and is suitable for application to a continuous wave magnetron used in microwave heating equipment such as a microwave oven.

  A general magnetron for microwave ovens that oscillates radio waves in the 2450 MHz band has an oscillation unit, an input unit, and an output unit. The oscillating portion includes a cylindrical anode cylinder (anode cylinder), a plurality of vanes protruding from the inner peripheral surface of the anode cylinder toward the central tube axis, and different sizes 2 having different diameters that alternately short-circuit the plurality of vanes. A pair of anode portions having two strap rings, a cathode portion having a spiral cathode (cathode) disposed on the central axis (that is, the tube axis) of the anode cylinder, and a pair disposed at both ends in the central axis direction of the anode cylinder It consists of pole pieces.

  In a magnetron configured in this way, when a voltage is applied between the anode part and the cathode part by supplying a current from the input part to the cathode, the oscillating part oscillates and outputs a microwave from the output part. (For example, refer to Patent Document 1).

JP, 2015-046360, A

  By the way, in order for the magnetron to have desired performance, it is necessary to use a material excellent in physical properties such as electrical conductivity, thermoelectricity, gas barrier property, and mechanical strength required for the anode part as a material for the anode part. Conventionally, nonmagnetic oxygen-free copper has been used as a material that meets such conditions.

  The price of copper materials such as non-magnetic oxygen-free copper is increasing, and it is desirable to reduce the amount of copper material used in order to reduce the cost of the magnetron. However, if the copper material is simply changed to another material, the performance of the magnetron will deteriorate depending on the physical properties of the material.

  Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide a magnetron that has a performance equal to or higher than that of the conventional one and reduces the amount of copper material used.

  In order to achieve the above object, a magnetron according to the present invention includes an anode cylinder extending in a cylindrical shape along a tube axis, an inner surface of the anode cylinder extending toward the tube axis, and a free end having a vane inscribed circle. And an anode portion having two strap rings having different diameters that alternately short-circuit the plurality of vanes, and a space formed by the free ends of the plurality of vanes. A cathode portion having a cathode disposed along the same, and a part or all of the anode portion is formed of a carbon material having graphene as a constituent element.

  According to the present invention, a carbon material containing graphene instead of a copper material is used for part or all of the anode portion. Graphene-based carbon materials have physical properties equivalent to or better than copper materials (electrical conductivity, thermoelectricity, gas barrier properties, mechanical strength, etc.) A magnetron with a reduced amount of copper material can be realized.

It is the longitudinal cross-sectional view of the whole magnetron based on this invention. It is the top view and side view of the cooling fin of the magnetron based on this invention.

  An embodiment of a magnetron according to the present invention will be described with reference to the drawings. The following embodiment is merely an example, and the present invention is not limited to this.

[1. Magnetron Configuration]
FIG. 1 is a diagram showing an outline of the configuration of the magnetron 1 of the present embodiment. FIG. 1 is a side view when viewed from a direction orthogonal to the tube axis m, which is the central axis of the magnetron 1, and a part (mainly the left half) is a longitudinal sectional view. The magnetron 1 is a magnetron for a microwave oven that generates microwaves in the 2450 MHz band. The magnetron 1 includes an oscillation unit 2 that generates microwaves in the 2450 MHz band, an input unit 4 that supplies power to the cathode 3 located at the center of the oscillation unit 2, and the microwaves oscillated from the oscillation unit 2 (magnetron 1 The output unit 5 is taken out to the outside. The oscillation unit 2, the input unit 4, and the output unit 5 are provided along the tube axis m. That is, the input unit 4 is provided on one end side (lower side in the drawing) of the oscillation unit 2 in the tube axis direction, and the output unit 5 is provided on the other end side (upper side in the drawing).

  The input unit 4 and the output unit 5 are joined to the oscillating unit 2 in a vacuum-tight manner by a metal seal 6 on the input side and a metal seal 7 on the output side, respectively. Thereby, the inside of the oscillation part 2 is kept in a vacuum state.

  The oscillation unit 2 includes an anode unit 10 and a cathode unit 11. The anode unit 10 includes an anode cylinder 12, a plurality of (for example, ten) vanes 13, and four annular strap rings 14. The anode cylinder 12 is formed in a cylindrical shape, and is arranged so that its central axis passes through the tube axis m, which is the central axis of the magnetron 1.

  Each vane 13 is formed in a plate shape, and is arranged radially around the tube axis m inside the anode cylinder 12. The outer end of each vane 13 is joined to the inner peripheral surface of the anode cylinder 12, and the inner end is a free end. A cylindrical space surrounded by the free ends of the plurality of vanes 13 is an electron action space. The four strap rings 14 are fixed to the upper end side and the lower end side in the tube axis m direction of the plurality of vanes 13 as a set of two large and small ones.

  The cathode portion 11 includes a cathode 3, two end hats 15, 16, and two support rods 17. There are two support rods 17 in total, one connected to the end hat 15 and one connected to the end hat 16. In the figure, the support rod 17 connected to the end hat 15 is supported. 17 is omitted. The cathode 3 is a spiral cathode and is provided on the tube axis m of the electron action space. End hats 15 and 16 are fixed to the input side end (lower end) and output side end (upper end) of the cathode 3 to prevent electrons from jumping out.

  Further, the cathode 3 is connected to the support rod 17 via the end hats 15 and 16. The support rod 17 is led out of the pipe via the relay plate 20.

  Further, the oscillating portion 2 includes a pair of pole pieces 21 and 22 on the inner side of the input side end portion (lower end portion) and the output side end portion (upper end portion) of the anode cylinder 12. 16 are provided so as to face each other with a space between 16 interposed therebetween.

  The pole piece 21 on the input side is provided with a through hole in the center thereof, and is formed in a funnel shape that extends toward the input side (downward) with the through hole as a center. On the other hand, the pole piece 22 on the output side is also provided with a through hole at the center, and is formed in a funnel shape that extends toward the output side (upward) with the through hole as a center. These pole pieces 21 and 22 are arranged such that the tube axis m passes through the center of the through hole.

  Furthermore, the upper end portion of the substantially cylindrical metal sealing body 6 extending in the tube axis m direction is fixed to the outer periphery of the pole piece 21 on the input side. The metal sealing body 6 is fixed to the lower end portion of the anode cylinder 12 in an airtight state. On the other hand, the lower end portion of the substantially cylindrical metal sealing body 7 extending in the tube axis m direction is fixed to the outer periphery of the pole piece 22 on the output side. The metal seal 7 is fixed to the upper end of the anode cylinder 12 in an airtight state.

  The ceramic seal 23 which comprises the input part 4 is joined to the lower end part of the metal sealing body 6 on the input side in an airtight state. That is, the support rod 17 planted on the ceramic stem 23 is connected to the cathode 3 through the inside of the metal sealing body 6.

  On the other hand, the output side metal sealing body 7 has an insulating tube 24 made of ceramic constituting the output unit 5 hermetically joined to the upper end portion thereof, and an exhaust pipe 25 is hermetically joined to the upper end of the insulating tube 24. Has been. Further, an antenna 26 led out from one of the plurality of vanes 13 passes through the pole piece 22 on the output side, extends to the upper end side through the inside of the metal seal 7, and the tip is the exhaust pipe 25 and is fixed in an airtight state.

  A pair of ring-shaped magnets 30 and 31 are provided on the outside of the metal sealing bodies 6 and 7 so as to sandwich the anode cylinder 12 in the tube axis m direction. Further, the anode cylinder 12 and the magnets 30 and 31 are surrounded by a yoke 32, and a strong magnetic circuit is formed by the pair of magnets 30 and 31 and the yoke 32.

  The yoke 32 closes the U-shaped input yoke 32A surrounding the input-side magnet 30 and the anode cylinder 12 and the U-shaped opening portion of the input yoke 32A and surrounds the output-side magnet 31. It comprises a letter-shaped output yoke 32B.

  Further, a radiator 34 constituted by a plurality of cooling fins 33 arranged side by side in the tube axis m direction is provided between the anode cylinder 12 and the input yoke 32A, and radiant heat from the cathode 3 and the oscillation unit 2 The heat loss is transmitted to the radiator 34 via the anode cylinder 12, and further transmitted from the radiator 34 to the input yoke 32A and the output yoke 32B so as to be discharged to the outside of the magnetron 1. Note that the material of the input yoke 32A and the output yoke 32B is, for example, iron, and the material of the cooling fin 33 is, for example, aluminum.

  The cathode 3 is connected to a filter circuit 35 having a coil and a feedthrough capacitor via a support rod 17. The filter circuit 35 is accommodated in the filter box 36. The outline of the configuration of the magnetron 1 is as described above.

[2. Anode configuration]
Next, the configuration of the anode unit 10 will be described in more detail with reference to FIG. 2A is an enlarged vertical cross-sectional view of the left half of the anode portion 10 and its peripheral portion, and FIG. 2B shows the anode cylinder 12 of the anode portion 10 viewed from the direction of the tube axis m. FIG.

  The anode cylinder 12 has a cylindrical inner peripheral portion 12A that forms an inner peripheral portion of the anode cylinder 12, a cylindrical shape having a larger diameter than the inner peripheral portion 12A, and forms an outer peripheral portion of the anode cylinder 12 and an inner peripheral portion 12A. It has a double structure composed of an outer peripheral portion 12B that reinforces. The outer diameter of the inner peripheral portion 12A and the inner diameter of the outer peripheral portion 12B are the same (or the outer diameter of the inner peripheral portion 12A is slightly larger), and the inner peripheral portion 12A is press-fitted inside the outer peripheral portion 12B. Thus, the inner peripheral portion 12A and the outer peripheral portion 12B are joined.

  The outer peripheral portion 12B is made of non-magnetic oxygen-free copper as a copper material as in the prior art, while the inner inner peripheral portion 12A is made of graphene unlike the conventional one. A carbon material used as an element (hereinafter also simply referred to as graphene) is used. For example, a metalizing method is used for joining the outer peripheral portion 12B made of a copper material and the inner peripheral portion 12A made of graphene. In the metalizing method, after a predetermined metal layer is formed on the surface of graphene made of nonmetal, nonmagnetic oxygen-free copper and the metal layer formed on the surface of graphene are brazed.

  A plurality of vanes 13 are joined to the inner peripheral surface of the inner peripheral portion 12 </ b> A of the anode cylinder 12. Also in this case, for example, a metalizing method is used for joining the inner peripheral portion 12A made of graphene and the vane 13 made of copper.

  Furthermore, the outer peripheral part 12B of the anode cylinder 12 is longer in the tube axis m direction than the inner peripheral part 12A, and the input side end (lower end) is on the input side from the input side end (lower end) of the inner peripheral part 12A. The output side end (upper end) also extends from the output side end (upper end) of the inner peripheral portion 12A to the output side (upper). That is, a step due to the difference in length between the inner peripheral portion 12A and the outer peripheral portion 12B in the tube axis m direction is formed inside both ends of the anode cylinder 12 in the tube axis m direction.

  In the anode cylinder 12, the end portion on the input side of the outer peripheral portion 12B and the metal sealing body 6 are joined by welding, and the end portion on the output side of the outer peripheral portion 12B and the metal sealing body 7 are joined by welding. Thus, the metal sealing bodies 6 and 7 are hermetically joined. Further, when the anode cylinder 12 and the metal sealing body 6 are joined, the outer peripheral portion of the metal sealing body 6 and the input side end portion (a stepped portion) of the inner peripheral portion 12A of the anode cylinder 12. The pole piece 21 is fixed to the anode portion 10 by sandwiching the input-side pole piece 21 between the two. Similarly, when joining the anode cylinder 12 and the metal sealing body 7, the outer peripheral portion of the metal sealing body 7 and the output side end portion (a stepped portion) of the inner peripheral portion 12 </ b> A of the anode cylinder 12. ), The pole piece 22 on the output side is sandwiched and the pole piece 22 is fixed to the anode portion 10.

  Further, the anode cylinder 12 has an inner peripheral portion 12A and an outer peripheral portion 12B with thicknesses selected to be about half that of the conventional anode cylinder. Therefore, the thickness of the entire anode cylinder 12 is approximately the same as that of a conventional anode cylinder.

  That is, the anode cylinder 12 has a structure in which about half of the anode cylinder 12 is replaced with graphene from nonmagnetic oxygen-free copper. By doing so, in the magnetron 1, it is possible to reduce the amount of copper material used for the anode portion 10 by the amount of the inner peripheral portion 12A, compared to the conventional magnetron.

Here, the physical properties of nonmagnetic oxygen-free copper and graphene will be described in detail. The conditions required for the material of the anode part 10 are mainly non-magnetic, high strength, good conductivity, high melting point, high thermoelectricity, and low outgassing. And so on. Therefore, here, among the physical properties of nonmagnetic oxygen-free copper, the physical properties related to the conditions required for the anode portion 10 will be described. Nonmagnetic oxygen-free copper is nonmagnetic, has a Young's modulus of 129.8 (GPa), an electrical conductivity of 5.9 × 10 ⁷ (S / m), a melting point of 1083 ° C., and a thermal conductivity of 391 (W / M · K), and it has the physical property of very little outgassing at high temperatures.

  Thus, nonmagnetic oxygen-free copper has higher strength, electrical conductivity, melting point, and thermoelectricity compared to other nonmagnetic metals (for example, stainless steel), and gas release at high temperatures is extremely low. Conventionally, it has been widely used as a material that satisfies the conditions required for the anode section 10.

On the other hand, graphene is nonmagnetic, has a Young's modulus of 11000 (GPa), an electrical conductivity of 7.5 × 10 ⁷ (S / m), a melting point of 3000 ° C., and a thermal conductivity of 4.84 × 10 ³ to It has a physical property of 5.3 × 10 ³ (W / m · K) and extremely low outgassing at high temperatures. In addition, graphene is excellent in gas barrier properties that prevent gas from passing therethrough.

  Thus, graphene is required for the anode section 10 because it has generally high strength, electrical conductivity, melting point, and thermoelectric power compared to non-magnetic oxygen-free copper, and also emits very little gas at high temperatures. It can be seen that it is very useful as a material that satisfies the above conditions at a higher level. Specifically, since graphene has higher conductivity than oxygen-free copper, it is considered that the electronic efficiency of the magnetron 1 can be improved if this graphene is used in the anode portion 10 instead of oxygen-free copper. . In addition, since graphene has a higher thermal power rate than oxygen-free copper, if this graphene is used for the anode portion 10 instead of oxygen-free copper, heat can be easily transferred from the anode portion 10 to the cooling fins 33 to dissipate heat. It is thought that the effect can be improved.

  Further, since graphene is excellent in gas barrier properties, this point is also suitable as a material for the anode part 10 that needs to keep the inside in a vacuum state.

  From the comparison result of such physical properties, it became clear that graphene is a material superior to non-magnetic oxygen-free copper as a material of the anode portion 10. Further, since graphene is excellent in gas barrier properties, it is more suitable for the anode portion 10 that needs to keep the inside in a vacuum state.

  In other words, if graphene is used instead of non-magnetic oxygen-free copper for the inner peripheral portion 12A of the anode cylinder 12, the use of the copper material used for the anode portion 10 while having performance equivalent to or higher than that of the conventional magnetron 1 It has been found that the amount can be reduced compared to conventional magnetrons.

[3. Summary and effect]
As described so far, in the magnetron 1 of the present embodiment, the anode cylinder 12 has a double structure including the inner peripheral portion 12A and the outer peripheral portion 12B, and the nonmagnetic oxygen-free copper is formed on the inner peripheral portion 12A. Instead, graphene was used. As described above, graphene is generally higher in strength, electrical conductivity, melting point, and thermoelectricity than non-magnetic oxygen-free copper, and has very little outgassing at high temperatures. It can be said that it is a material superior to non-magnetic oxygen-free copper.

  Therefore, in the magnetron 1 using graphene for the inner peripheral portion 12A of the anode cylinder 12, it is possible to reduce the amount of copper material used for the anode portion 10 while having performance equal to or higher than that of the conventional magnetron.

  Further, the outer peripheral portion 12B of the anode cylinder 12 is made of non-magnetic oxygen-free copper as in the prior art, and both end portions of the outer peripheral portion 12B in the tube axis m direction and the metal sealing bodies 6 and 7 are joined by welding. I tried to do it. As described above, the anode cylinder 12 and the metal sealing bodies 6 and 7 can be easily joined by the same method (welding) as in the prior art.

  On the other hand, for example, the entire anode cylinder 12 may be graphene. In this case, the performance of the magnetron 1 can be further improved, and the amount of copper material used for the anode part 10 can be further reduced. On the other hand, for the joining with the metal sealing bodies 6 and 7, Since it joins by the metalizing method etc. which are different from the conventional method, it will be inferior about the ease of joining.

  Furthermore, in the present embodiment, the anode cylinder 12 has a double structure including the inner peripheral portion 12A and the outer peripheral portion 12B, and the length of the inner peripheral portion 12A in the tube axis m direction is set to the tube axis m of the outer peripheral portion 12B. A step for sandwiching the pole pieces 21 and 22 between the metal sealing bodies 6 and 7 is formed inside the both ends of the anode cylinder 12 in the tube axis m direction so as to be shorter than the length in the direction. did. That is, in the anode cylinder 12, a step is formed by superposing two cylinders having different lengths and diameters in the tube axis m direction.

  In this way, the anode cylinder 12 of the present embodiment has a step difference as compared to the case where the step is formed by scraping the inside of both ends in the direction of the tube axis m as in a conventional single-structure anode cylinder. Is easy to form, and although it has a double structure, the manufacturing cost is reduced.

[4. Other Embodiments]
[4-1. Other Embodiment 1]
In the above-described embodiment, graphene is used for the inner peripheral portion 12A of the anode cylinder 12, and oxygen-free copper is used for the outer peripheral portion 12B. For example, the inner peripheral portion 12A is joined to the vane 13 made of a copper material. The metallizing method was used. For example, the entire inner peripheral portion 12A formed of graphene may be plated with copper. In this case, the anode cylinder 12 composed of the inner peripheral portion 12A and the outer peripheral portion 12B to which the copper plating is applied is joined to other parts in the same manner as the conventional anode cylinder made of oxygen-free copper (such as brazing). Since it becomes possible, manufacturing cost can be held down.

  Further, in this case, the amount of copper used is increased by the amount of copper plating compared to the anode cylinder 12 of the above-described embodiment. However, compared to the case where all of the anode cylinder 12 is made of copper, copper is used. The amount used can be reduced sufficiently.

[4-2. Other Embodiment 2]
In the above-described embodiment, the anode cylinder 12 has a double structure of the inner peripheral portion 12A and the outer peripheral portion 12B. However, the present invention is not limited to this, and the anode cylinder 12 may have a single structure similar to the conventional one, and the entire anode cylinder 12 may be formed of graphene. In this case, for example, a metalizing method may be used for joining the anode cylinder 12 and other components. In this way, the amount of copper used can be reduced as compared with the above-described embodiment.

  Also in this case, the entire anode cylinder 12 made of graphene may be plated with copper, and may be joined to other components by a method similar to the conventional method (such as brazing).

  Furthermore, the present invention is not limited thereto, and for example, the anode cylinder 12 may be a triple structure including an inner peripheral portion, an outer peripheral portion, and a central portion therebetween, and only the central portion may be graphene. That is, at least a part of the anode cylinder 12 only needs to be formed of graphene. Not limited to this, the outer peripheral portion 12B of the anode cylinder 12 may be formed of graphene instead of the inner peripheral portion 12A.

  In the above-described embodiment, the inner peripheral portion 12A and the outer peripheral portion 12B of the anode cylinder 12 are joined by press-fitting. However, the present invention is not limited to this, and the inner portion made of graphene is formed inside the outer peripheral portion 12B by sputter deposition. The peripheral portion 12A may be formed.

  Furthermore, in the above-described embodiment, the inner peripheral portion 12A and the outer peripheral portion 12B of the anode cylinder 12 have the same thickness. However, the present invention is not limited to this. For example, the inner peripheral portion 12A is thicker than the outer peripheral portion 12B. It may be thinned.

[4-3. Other Embodiment 3]
Further, in the above-described embodiment, graphene is used for the anode cylinder 12 of the anode unit 10. However, the present invention is not limited to this, and graphene may be used in other parts constituting the anode unit 10. Specifically, graphene may be used as a material for the vane 13 instead of a copper material. Further, instead of a copper material, graphene may be used as a material for the strap ring 14. That is, all of the anode unit 10 may be formed of graphene. As with the anode cylinder 12, the vane 13 and the strap ring 14 are also non-magnetic, have high strength, have good electrical conductivity, have a high melting point, have a high thermoelectric efficiency, and have a low outgassing. Therefore, by replacing the material used for the vane 13 and the strap ring 14 with graphene, the amount of copper used can be further reduced and the performance of the magnetron 1 can be improved. It is done.

  Further, with respect to portions other than the anode portion 10, the material to be used may be replaced with graphene for portions that require the same conditions as the anode portion 10. Specifically, graphene may be used instead of a copper material as the material of the pole pieces 21 and 22. Further, instead of a copper material, graphene may be used as the material of the antenna 26.

[4-4. Other Embodiment 4]
Further, in the above-described embodiment, a carbon material having graphene as a constituent element is used for the anode cylinder 12 of the anode unit 10. For example, graphite (graphite), carbon nanotube, fullerene, and the like are used as the carbon material. Shall be included. Note that other carbon materials may be used as long as they have graphene as a constituent element.

[4-5. Other Embodiment 5]
Furthermore, in the above-described embodiment, the configuration of the anode cylinder 12 of the magnetron 1 has been mainly described. However, portions other than the configuration of the anode cylinder 12 may be different from the configuration of the magnetron 1 described above. Good.

  DESCRIPTION OF SYMBOLS 1 ... Magnetron, 2 ... Oscillation part, 3 ... Cathode, 4 ... Input part, 5 ... Output part, 6, 7 ... Metal sealing body, 10 ... Anode part, 11 ... Cathode part, 12 …… Anode cylinder, 12A …… Inner circumference, 12B …… Outer circumference, 13 …… Bain, 14 …… Strap ring, 21, 22 …… Pole piece, 26 …… Antenna, m …… Tube axis.

Claims (6)

An anode cylinder that extends cylindrically along the tube axis, a plurality of vanes that extend from the inner surface of the anode cylinder toward the tube axis, and whose free ends form a vane inscribed circle, and the plurality of vanes alternately An anode portion having two strap rings of different diameters to be short-circuited;
A magnetron comprising: a cathode portion having a cathode disposed along the tube axis in a space formed by the free ends of the plurality of vanes;
A magnetron, wherein part or all of the anode part is formed of a carbon material having graphene as a constituent element. 2. The magnetron according to claim 1, wherein a part or all of an anode cylinder of the anode part is formed of a carbon material including the graphene as a constituent element. The anode cylinder is
It has a double structure composed of a cylindrical inner peripheral part and an outer peripheral part that is cylindrical with a larger diameter than the inner peripheral part,
The magnetron according to claim 2, wherein at least one of the inner peripheral portion and the outer peripheral portion is formed of a carbon material having graphene as a constituent element. The inner circumference of the anode cylinder has a shorter length in the tube axis direction than the outer circumference,
The anode cylinder is
The magnetron according to claim 3, wherein a step due to a difference in length between the inner peripheral portion and the outer peripheral portion in the tube axis direction is formed inside both ends in the tube axis direction. The magnetron according to any one of claims 1 to 4, wherein a part or all of the anode part formed of a carbon material containing graphene as a constituent element is plated with a predetermined metal. A pole piece that is disposed on both ends of the anode cylinder in the tube axis direction and guides magnetic flux to the space between the free ends of the plurality of vanes and the cathode;
And at least one antenna drawn from the vane,
The magnetron according to any one of claims 1 to 5, wherein at least one of the pole piece and the antenna is made of a carbon material having graphene as a constituent element.

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