JP6356992B2 - Choke coil and magnetron - Google Patents

Description

  The present invention relates to a choke coil, and more particularly to a choke coil disposed in a filter box of a magnetron.

  The magnetron has an oscillation unit, an input unit, and an output unit. The oscillating part includes an anode part composed of an anode cylinder and a plurality of vanes arranged on the inside thereof, a central axis of the anode cylinder, that is, a cathode part of a filament placed on the tube axis, and both ends of the anode cylinder in the tube axis direction. It is comprised with a pair of pole piece arrange | positioned on the surface.

  The input unit includes a stem that supports a cathode lead that extends through one pole piece of the oscillation unit, and the output unit includes an antenna that extends through the other pole piece of the oscillation unit. The pair of pole pieces is sandwiched between permanent magnets, and converges the magnetic flux in the working space between the anode part and the cathode part.

  The magnetron configured as described above supplies a filament current from the input section to the cathode section, and when a voltage is applied between the anode section and the cathode section, it oscillates and outputs a microwave from the output section. In the case of a general magnetron for a microwave oven, the oscillation frequency is 2450 MHz. Since a part of the oscillation output leaks from the input unit and interferes with external equipment, the input unit is shielded by a filter box to prevent radio wave leakage. Further, the oscillation output oscillates not only the fundamental wave of 2450 MHz but also a radio wave of a wide band due to electronic disturbances, and the filter box prevents the leakage of these radio waves.

  The filter box has a pair of feedthrough capacitors that are connected to an external power source and also serve as external input terminals. A pair of choke coils connected between the pair of cathode terminals and the pair of feedthrough capacitors are disposed in the filter box.

  For example, as shown in FIG. 4, each choke coil is a core type inductor in which a magnetic core 100a is inserted and fixed in a coil 100b in which a copper wire is wound with a winding diameter similar to the outer diameter of the magnetic core 100a. 100 and an air-core type inductor 101 having a winding diameter similar to the outer diameter of the magnetic core 100a and wound with a copper wire and having a winding interval wider than that of the core-type inductor 100. It has become.

  The choke coil constituting the filter circuit consumes the microwave leaking from the cathode part as heat. In addition, when the magnetic permeability of the magnetic core decreases due to overheating, the inductance of the choke coil decreases, and microwave leakage increases. Furthermore, the air-core type inductor is positioned so as to attenuate the maximum amplitude portion of the standing wave of the fundamental wave of 2450 MHz, which is the maximum component of the leaky wave, so as not to reach the core type inductor. (See, for example, Patent Document 1).

JP2013-77516A

  Actually, in the choke coil, during the operation of the magnetron, the temperature of the magnetic core 100a in contact with the coil 100b rises as current flows through the copper wire and the coil 100b generates heat. In particular, when an inverter power supply is connected to the filter box, a high-frequency current flows through the copper wire of the choke coil, so that the temperature of the magnetic core 100a tends to increase.

In the choke coil, as described above, the temperature of the magnetic core 100a increases and the magnetic permeability of the magnetic core 100a changes. Noise suppression function by a change in the magnetic permeability is that to reduce.

  Thus, the magnetron choke coil reduces the noise suppression function as the temperature of the magnetic core increases, so in order to obtain a good noise suppression function, how can the temperature of the magnetic core be increased? It is important to suppress it.

  Therefore, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide a choke coil that can suppress a temperature rise and obtain a good noise suppression function.

In order to achieve the above object, a choke coil according to the present invention includes a core-type inductor including a first coil, a magnetic core inserted into the first coil, and a series connection with the first coil. ; and a air-core type inductor comprising the second coil connected, the first coil of the core type inductor are different in inner diameter in a portion and the remaining portion, the inner diameter of the portion is, the magnetic body they become larger than the outer diameter of the magnetic core so as not to contact with the core, the inner diameter of the remaining portion, are substantially equal to the outer diameter of the magnetic core so as to contact with the magnetic core, that Features.

In addition, the magnetron according to the present invention includes a core-type inductor composed of a first coil and a magnetic core inserted into the first coil, and a second coil connected in series with the first coil. ; and a air-core type inductor comprised in the first coil of the core type inductor are different in inner diameter in a portion and the remaining portion, the inner diameter of said portion is the magnetic so as not to contact with the magnetic core they become larger than the outer diameter of the body core, the inner diameter of the remaining portion has a choke coil which is substantially equal to the outer diameter of the magnetic core so as to contact with the magnetic core.

  ADVANTAGE OF THE INVENTION According to this invention, the choke coil and magnetron which can suppress the temperature rise of a choke coil and can obtain a favorable noise suppression function can be provided.

It is the whole longitudinal cross-sectional view in one Embodiment of the magnetron based on this invention. It is a cross-sectional view of the filter box in one embodiment of the magnetron according to the present invention. It is the side view and longitudinal cross-sectional view of the choke coil in one Embodiment of the magnetron based on this invention. It is the side view and longitudinal cross-sectional view of the choke coil in the conventional magnetron.

  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.

  FIG. 1 is a longitudinal sectional view showing an outline of a magnetron 1 of the present embodiment. The magnetron 1 is a magnetron for a microwave oven that generates a fundamental wave in the 2450 MHz band.

  The magnetron 1 has a magnetron body 2 and a filter box 3. The magnetron body 1 includes an oscillating unit 4, an input unit 5, and an output unit 6. The oscillating unit 4 is provided with an input unit 5 on one end side in the tube axis m direction and an output unit 6 on the other end side. ing.

  The tube axis m is the central axis of the magnetron body 2. In the following description, one end side of the magnetron body 2 in the tube axis m direction is defined as a lower end side and an input side, and the other end side is defined as an upper end side and an output side.

  The oscillating unit 4 includes an anode unit 7 and a cathode unit 8, and the anode unit 7 includes an anode cylinder 9 and a plurality of vanes 10 protruding from the inner peripheral surface of the anode cylinder 9 toward the tube axis m. have.

  The cathode portion 8 includes a filament 11, a pair of end hats 12 and 13, a cathode center lead 14, and a cathode side lead 15. The filament 11 is disposed on the tube axis m, and the end hats 12 and 13 are provided at both upper and lower ends of the filament 11.

  The cathode center lead 14 has an upper end fixed to the end hat 12 and is connected to the filament 11 via the end hat 12. The cathode side lead 15 has an upper end fixed to the end hat 13 and is connected to the filament 11 via the end hat 13. Further, the lower ends of the cathode center lead 14 and the cathode side lead 15 respectively extend toward the input unit 5 located on the lower end side of the magnetron body 2.

  The vane 10 is disposed so that a free end, which is the tip thereof, maintains a predetermined distance from the filament 11. An annular space formed between the free end of the vane 10 and the filament 11 is an action space.

  A pair of substantially funnel-shaped (substantially mortar-shaped) pole pieces 16 and 17 are provided on both upper and lower ends of the anode cylinder 9 so as to face each other with the working space in the direction of the tube axis m. Below the input-side pole piece 17 provided on the lower end side of the anode cylinder 9, an input section 5 for supplying a filament applying current and a magnetron driving high voltage is provided. The input unit 5 includes a ceramic stem 18 that holds the cathode center lead 14 and the cathode side lead 15.

  The input unit 5 is joined to the anode cylinder 9 in a vacuum-tight manner by a cylindrical metal sealing body 19 extending in the tube axis m direction, and is covered with the filter box 3.

  An output unit 6 having an antenna lead 20 for transmitting and radiating microwaves is provided above the output-side pole piece 16 provided on the upper end side of the anode cylinder 9.

  The output unit 6 includes an antenna lead 20, an insulating cylinder 21, and an exhaust pipe 22. The exhaust pipe 22 is joined to the upper end of the insulating cylinder 21. The antenna lead 20 has a lower end connected to one of the plurality of vanes 10, an upper end extending upward along the tube axis m, passing through the insulating cylinder 21, and being sandwiched and fixed to the exhaust pipe 22.

  The output unit 6 is joined to the anode cylinder 9 in a vacuum-tight manner by a cylindrical metal sealing body 23 extending in the tube axis m direction.

  Below the input-side pole piece 17 and above the output-side pole piece 16, annular permanent magnets 24, 25 made of a pair of ferrite are provided on the outer peripheral side of the metal seals 19, 23, and the anode cylinder 9 is tubed. They are provided opposite to each other in the axis m direction.

  The anode cylinder 9 and the annular permanent magnets 24 and 25 are covered with frame-shaped yokes 26 and 27. In the annular permanent magnets 24 and 25, the surface facing the pole pieces 16 and 17 and the pole pieces 16 and 17 are magnetically coupled, and the opposite surface and the frame-shaped yokes 26 and 27 are magnetically coupled. Magnetic fields are supplied to the working space between the vane 10 and the filament 11 by the magnetic circuit formed by the coupling.

  The outline of the configuration of the magnetron 1 is as described above.

  Next, the filter box 3 and the internal configuration thereof will be described in more detail with reference to FIG.

  The input unit 5 covered with the filter box 3 includes a ceramic stem 18 that holds the cathode center lead 14 and the cathode side lead 15, and a pair of cathode terminals 30 and 31 connected to the cathode center lead 14 and the cathode side lead 15, respectively. have.

  A two-terminal feedthrough capacitor 32 that passes through the side wall of the filter box 3 is attached. The feedthrough capacitor 32 has two terminals 33 and 34 located outside the filter box 3 and two terminals 35 and 36 located inside. The two terminals 35 and 36 located on the inner side are also referred to as inner terminals 35 and 36 hereinafter.

  The pair of cathode terminals 30, 31 are positioned at substantially the center in the filter box 3, and the choke coil 37 is interposed between the cathode terminals 30, 31 and the inner terminals 35, 36 of the feedthrough capacitor 33. , 38 are connected in series. The choke coils 37 and 38 and the feedthrough capacitor 32 constitute a filter circuit.

  The choke coil 37 connected between the cathode terminal 30 connected to the cathode center lead 14 and the inner terminal 35 is called a center lead side choke coil 37, and is connected to the cathode terminal 31 connected to the cathode side lead 15. The choke coil 38 connected to the inner terminal 36 is referred to as a side lead side choke coil 38.

  The center lead side choke coil 37 is a coil 40a as a first coil formed by closely winding a wire such as a copper wire without gaps, and a cylindrical shape at least partially inserted into the coil 40a and fixed. A core type inductor 40 composed of a magnetic core 40b made of ferrite and the like, and an air-core coil 41a as a second coil formed by loosely winding a wire such as a copper wire so that a gap is formed in a spiral. The air core type inductor 41 is connected in series. The coil 40a of the core type inductor 40 and the air core coil 41a of the air core type inductor 41 are formed of a single wire. Here, for example, the diameter of the wire is 1.0 to 1.4 mm, and the diameter of the magnetic core 40b is about 2.5 to 4 mm.

  The center lead side choke coil 37 has an air core type inductor 41 side connected to a cathode terminal 30 via a bent wire 42 having a predetermined length, and a core type inductor 40 side connected to an inner terminal 35.

  One side lead side choke coil 38 has the same configuration as the center lead side choke coil 38, and a magnetic core 50a as a first coil and a magnetic core at least partially inserted and fixed in the coil 50a. A core type inductor 50 constituted by 50b and an air core type inductor 51 constituted by an air core coil 51a as a second coil are connected in series. The coil 50a of the core type inductor 50 and the air core coil 51a of the air core type inductor 51 are also formed by one wire.

  The side lead choke coil 38 has an air core type inductor 51 side connected to a cathode terminal 31 via a bent wire 52 having a predetermined length, and a core type inductor 50 side connected to an inner terminal 36.

  Here, the side lead side choke coil 38 will be described in more detail with reference to FIG. Since the center lead side choke coil 37 has the same configuration as the side lead side choke coil 38, the description thereof is omitted.

  FIG. 3A is a side view of the side lead side choke coil 38, and FIG. 3B is a cross-sectional view of the core type inductor 50 of the side lead side choke coil 38.

  As shown in FIG. 3B, the coil 50a of the core type inductor 50 of the side lead side choke coil 38 includes a part 60 on the inner terminal 36 side (referred to as a terminal side part) 60 and an air core type inductor 51 side. (This is referred to as the air core side portion) 61, and the diameter of the air core side portion 61 is larger than that of the terminal side portion 60. For example, if the entire coil 50a is about 10 turns, the terminal side portion 60 is about 3 turns and the air core side portion 61 is about 7 turns. The terminal side portion 60 and the air core side portion 61 are both closely wound.

  The magnetic core 50b of the core type inductor 50 has a predetermined length so that one end portion reaches the inside of the air core side portion 61 of the coil 50a and the other end portion protrudes outward from the terminal side portion 60. Thus, it is inserted and fixed in the coil 50a.

Terminal side portion 60 of the coil 50a is fixed an inner diameter substantially equal to the outer diameter of the magnetic core 50b, in contact with the outer periphery of the inserted magnetic core 50b in the coil 50 a, the magnetic core 50b It comes to hold. In contrast, the air-core portion 61 of the coil 50a is constant gap between an inner diameter larger than the outer diameter of the magnetic core 50b, the outer periphery of the inserted magnetic core 50b in the coil 50 in a (For example, a gap of about the outer diameter of the wire) is vacant and is not in contact with the magnetic core 50b.

In other words, the magnetic core 50b, of the portion inserted into the coil 50 a, only the outer peripheral portion located inside the terminal portion 60 is in contact with the coil 50 a, the other portion (i.e., the air-core the outer peripheral portion) located inside the side portions 61, so as not to contact the coil 50 a.

Further, the coil 51 a of the air core type inductor 51 connected in series with the core type inductor 50 has the same inner diameter as the air core side portion 61 of the coil 50 a of the core type inductor 50.

  The side lead side choke coil 38 has such a configuration, and the center lead side choke coil 37 has the same configuration although the description is omitted.

  Here, effects obtained by the configuration of the side lead side choke coil 38 of the present embodiment will be described. This effect is the same as that obtained by the configuration of the center lead side choke coil 37. First, in order to clarify the effect, a conventional choke coil to be compared will be described with reference to FIG. Similarly to the side lead side choke coil 38 of the present embodiment, the conventional choke coil also includes a core type inductor 100 in which a magnetic core 100a is inserted and fixed to the coil 100b, and a core type inductor 100 including an air core coil 101a. Are connected in series. The size of the magnetic core 100a, the amount of protrusion from the coil 100b, and the like are the same as those of the side lead side choke coil 38 of the present embodiment.

  In the conventional choke coil, as shown in FIG. 4B, the inner diameter of the coil 100b of the core type inductor 100 is substantially equal to the outer diameter of the magnetic core 100a in all parts. That is, the magnetic core 100a is fixed so that the entire outer periphery of the portion inserted into the coil 100b is in contact with the coil 100b.

In contrast to such a conventional choke coil, in the side lead side choke coil 38 of the present embodiment, as shown in FIG. 3B, the inner diameter of the coil 50a of the core type inductor 50 is the terminal side portion 60. And the air core side portion 61 are different. The inner diameter of the terminal-side portion 60 is substantially equal to the outer diameter of the magnetic core 50b, and the inner diameter of the air-core-side portion 61 is larger than the outer diameter of the magnetic core 50b, whereby the coil 50 of the magnetic core 50b. Of the portions inserted into a , only the outer periphery of the portion located inside the terminal side portion 60 is in contact with the coil 50a, and the other portion (ie, the portion located inside the air core side portion 61) the outer periphery of) is adapted not to contact the coil 50 a.

  Thereby, the side lead side choke coil 38 has a smaller contact area between the coil 50a of the core type inductor 50 and the magnetic core 50b than the conventional choke coil.

  By the way, in the side lead side choke coil 38, during operation of the magnetron 1, a high frequency current flows through the wire, and the core type inductor 50 and the air core type inductor 51 generate heat. At this time, the temperature of the magnetic core 50b inserted in the coil 50a rises as the heat of the coil 50a is transmitted also from the portion in contact with the coil 50a.

  Therefore, in the side lead side choke coil 38 of the present embodiment, the contact area between the coil 50a and the magnetic core 50b is made smaller than that of the conventional choke coil, so that the coil 50a can be compared with the conventional choke coil. It is possible to reduce the transfer of heat to the magnetic core 50b and suppress the temperature rise.

  Furthermore, in the side lead side choke coil 38 of the present embodiment, as described above, since the temperature rise of the magnetic core 50b can be suppressed, the decrease in inductance is suppressed and the decrease in noise characteristic function is suppressed. be able to. Similarly, since the center lead side choke coil 37 can also suppress the temperature rise of the magnetic core 40b, it is possible to suppress a decrease in inductance and a decrease in noise characteristic function. Thus, according to the choke coils 37 and 38 of the present embodiment, a better noise suppression function can be obtained as compared with the conventional choke coil.

  On the other hand, when an inverter power supply is connected to the filter box 3, when the inductance of the choke coils 37 and 38 is reduced, the filament current of the magnetron 1 is increased and stable oscillation cannot be performed. Therefore, in the present embodiment, the magnetron 1 can be stably oscillated by suppressing a decrease in inductance of the choke coils 37 and 38.

  In the above-described embodiment, the inner diameter of the terminal side portion 60 of the coil 50a of the core type inductor 50 is made substantially equal to the outer diameter of the magnetic core 50b, and the inner diameter of the air core side portion 61 is made equal to that of the magnetic core 50b. It was larger than the outer diameter. In other words, the terminal side portion 60 is brought into contact with and fixed to the magnetic core 50b inserted in the coil 50a, and a gap is formed between the air core side portion 61 and heat transfer is suppressed.

  On the contrary, the inner diameter of the terminal side portion 60 is made larger than the outer diameter of the magnetic core 50b, and the inner diameter of the air core side portion 61 is made equal to the outer diameter of the magnetic core 50b, and inserted into the coil 50a. The air core side portion 61 may be brought into contact with and fixed to the magnetic core 50b, and the heat transfer may be suppressed by leaving a gap with the terminal side portion 60.

  However, the side lead side choke coil 38 is a core type inductor 50 and an air core type inductor 51 connected in series, and the air core coil 51a of the air core type inductor 51 also generates heat.

Thus, the portion that possible distance apart than the air-core coil 51a, i.e. be in contact with the magnetic core 50 b at the terminal portion 60, in reducing the temperature rise of the magnetic core 50 b is desirable. For this reason, in the embodiment described above, and a terminal side portion 60 that is remote distance than the air-core coils 51a to fix in contact with the magnetic core 50 b.

  In the embodiment described above, assuming that the entire coil 50a has about 10 turns, the terminal side portion 60 has about 3 turns and the air core side portion 61 has about 7 turns. That is, the ratio of the size of the terminal side portion 60 and the air core side portion 61 was set to about 3: 7. Not only this but this ratio may be changed. Specifically, if it is desired to fix the magnetic core 50b more firmly, the ratio of the terminal side portion 60 may be increased, and if it is desired to further reduce the transfer of heat to the magnetic core 50b, the empty space What is necessary is just to enlarge the ratio of the core side part 61. FIG.

  Furthermore, in the above-described embodiment, the size of the gap formed between the outer periphery of the magnetic core 50b and the air core side portion 61 is set to be about the outer diameter of the wire constituting the coil 50a. Not limited to this, the gap may be narrower than the outer diameter of the wire or wider than the outer diameter of the wire as long as it does not contact the magnetic core 50b. In addition, when making the magnitude | size of a clearance gap wider than the outer diameter of a wire, it is desirable to make it shorter than the insulation distance between the air-core side part 61 and the filter box 3. FIG.

Furthermore, in the above-described embodiment, the inner diameter of the coil 51a of the air core type inductor 51 connected in series with the core type inductor 50 is made equal to the inner diameter of the air core side portion 61 of the coil 50a of the core type inductor 50. However, the inner diameter of the coil 51a of the air core type inductor 51 may be different from the inner diameter of the air core side portion 61 of the coil 50a of the core type inductor 50. For example, the inner diameter of the coil 51a of the air core type inductor 51 may be made equal to the inner diameter of the terminal side portion 60 of the coil 50a of the core type inductor 50.

  Furthermore, in the above-described embodiment, the center lead side choke coil 37 and the side lead side choke coil 38 have the same configuration. For example, the center lead side choke coil 37 and the side lead side choke coil 38 have Different configurations may be used as long as the temperature rises of the magnetic cores 40b and 50b are different.

  Specifically, when the temperature rise degree is larger, the inner diameter of the air core side portion of the coil of the core type inductance is larger than the temperature rise degree is smaller, that is, the magnetic core and the air core. The heat radiation effect may be further increased by increasing the gap with the side portion.

  In addition, the ratio of the air core side portion to the coil of the core type inductance is larger when the temperature rise degree is larger than the temperature rise degree is smaller, that is, between the magnetic core and the terminal side portion. The contact surface property may be reduced to further reduce the transmission of temperature.

  In this way, the center lead side choke coil 37 and the side lead side choke coil 38 change the inner diameter of the air core side portion of the coil, the ratio of the size of the air core side portion to the size of the coil, and the like. May be.

  1 ... Magnetron, 3 ... Filter box, 37 ... Center lead side choke coil, 38 ... Side lead side choke coil, 40, 50 ... Core type inductor, 40a, 50a ... Coil, 40b, 50b ... Magnetic core, 41, 51 ... Air core type inductor, 41a, 51a ... Air core coil.

Claims (5)

A core type inductor composed of a first coil and a magnetic core inserted into the first coil;
An air-core type inductor comprising a second coil connected in series with the first coil,
The first coil of the core type inductor is:
Different inner diameter at a portion with the rest of the inner diameter of said portion is said is larger than the outer diameter of the magnetic core so as not to contact with the magnetic core, the inner diameter of the remaining portion, the magnetic core choke coil, characterized in that it is substantially equal to the outer diameter of the magnetic core so as to contact with. The first coil of the core type inductor is:
The inner diameter of the portion to be the air-core type inductor side, said is larger than the outer diameter of the magnetic core so as not to contact with the magnetic core, the inner diameter of the remaining portion is in contact with the magnetic core Yo choke coil according to claim 1, characterized in that is substantially equal to the outer diameter of the magnetic core. The first coil of the core type inductor is:
The choke coil according to claim 1, wherein the wire is closely wound. The second coil of the air core type inductor is:
Choke coil according to claim 2, wherein the inner diameter of the portion to be the air-core type inductor side of the core type inductor, to become the same inner diameter. A magnetron comprising the choke coil according to claim 1.

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