JP3397826B2 - Magnetron anode body - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetron anode body. More specifically, the present invention relates to a magnetron anode body in which a strap ring is not damaged by heat even when the output of the magnetron is increased. 2. Description of the Related Art An anode of a magnetron generally used for a microwave oven or the like has a structure as shown in FIG. In FIG. 3, (a) is an explanatory plan view, (b) is a cross-sectional view taken along line AA of (a), and an anode body is arranged radially on an anode cylinder 1 and its inner peripheral surface. And a small-diameter strap ring 3 and a large-diameter strap ring 4 that connect every other vane 2. Strap rings 3 and 4 are bain 2
May be provided only at one end in the axial direction, or may be provided at both ends of the vane 2 in the axial direction as shown in FIG. It is common to connect the vanes. In this structure, an even number of small cavities 5 surrounded by the two vanes 2 and the peripheral wall of the anode cylinder 1 are formed, and the whole forms a resonance cavity of the magnetron. Since the magnetron normally oscillates in the π mode, each small cavity 5 oscillates by shifting the phase by π radian. for that reason,
In order to stabilize the oscillation of the magnetron, every other vane is connected by the small and large diameter strap rings 3 and 4 so as to have the same potential. [0004] A pair of magnetic pole pieces (not shown) are disposed at both open ends of the anode cylinder 1.
A magnet (not shown) for forming an orthogonal electrostatic magnetic field in combination with a high voltage applied to the working space between the cathode (not shown) and the vane 2 disposed at a portion facing the tip 2a of the vane 2 Generates a magnetic field. [0005] As a material constituting the anode body of the magnetron having such a structure, oxygen-free copper having good heat conduction and electric conduction and low gas emission is generally used. However, the tip 2 of the vane 2 near the cathode in the anode body
The strap rings 3 and 4 provided at the a portion and the tip of the vane 2 are likely to be heated to a high temperature. Since the strap rings are particularly thin rings, the strap rings 3 and 4 made of oxygen-free copper have high thermal stress. Deformation such as bending or bending is likely to occur due to repetition, and eventually breaks. Since the resonance frequency of each small cavity is determined by the capacitance between the strap rings (C), the capacitance between the strap rings and the vanes (C), and the inductance (L) of the vanes, the strap rings may break, Deformation changes the resonance frequency, and consequently the oscillation frequency. In addition, when the strap ring is cut, the purpose of the strap ring to stabilize the oscillation by connecting the vanes having the same potential is not achieved, and the magnetron characteristics are degraded. On the other hand, there is a tendency that the cooking ability of a microwave oven has been improved in recent years.
There is also a movement to increase the output power to W, and even 1000 W. With such a high output, research on magnetron materials that can withstand high temperatures is being promoted. As such a material, for example, Japanese Unexamined Patent Publication No.
As described in Japanese Patent No. 121932, it has been proposed to use a precipitation hardening type metal having improved mechanical strength by adding zirconium to a strap ring or the like. [0008] However, the above-described oxygen-free copper containing zirconium is expensive and inferior in electrical conductivity. Also, the strap ring is brazed to the vane with a brazing material or the like, but oxygen-free copper containing zirconium has poor wettability with respect to the silver brazing material used for brazing, reducing the efficiency and reliability of the brazing work. There's a problem. The present invention minimizes the use of oxygen-free copper containing zirconium, which is expensive and degrades the electrical characteristics, and can maintain high mechanical strength to cope with high output of a microwave oven or the like. It is an object of the present invention to provide a magnetron anode body having high performance. A magnetron anode body according to the present invention comprises an anode cylinder, a plurality of vanes radially arranged on the inner peripheral surface of the anode cylinder, and every other vane. ,
A magnetron anode body comprising a large-diameter strap ring and a small-diameter strap ring that are electrically connected,
The large-diameter strap ring is made of oxygen-free copper, the small-diameter strap ring is made of oxygen-free copper containing zirconium, and the large-diameter strap ring is arranged with a gap of 1 mm or more with respect to the small-diameter strap ring. It is characterized by the following. According to the present invention, the inner small-diameter strap ring is formed of oxygen-free copper containing zirconium, and the outer large-diameter strap ring is arranged with a gap of 1 mm or more from the small-diameter strap ring. The temperature rise of the large-diameter strap ring can be suppressed low, and sufficient mechanical strength can be maintained even when oxygen-free copper is used. That is, in the anode body of the magnetron, the temperature of the tip of the vane closest to the cathode rises most due to collision of electrons and radiant heat from the cathode. The amount of heat at the tip of the vane propagates through the vane formed of oxygen-free copper, flows to the anode cylinder on the opposite side, and is dissipated to the outside, resulting in a temperature gradient. Therefore, the temperature of the small-diameter strap ring on the tip side of the vane becomes higher, but the temperature of the large-diameter strap ring becomes lower than that of the small-diameter strap ring, and the temperature decreases as the distance from the vane tip section increases. It is preferable that the position of the small diameter strap ring is connected to the position where the potential of the vane tip is as high as possible, but the large diameter strap ring has little effect on the characteristics depending on the position, so adjust the capacity etc. between the strap ring and the vane Thus, the oscillation frequency can be kept the same and can be arranged at a position far from the tip of the vane. As a result, it is 1 more than a small diameter strap ring.
By arranging the large-diameter strap rings at positions spaced apart by not less than mm, the temperature does not become too high, and even if formed from oxygen-free copper, there is no breakage before the small-diameter strap rings. Next, the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory sectional view showing a vane and a strap ring portion of an embodiment of the magnetron anode body of the present invention. In FIG. 1, reference numerals 1 to 4 denote the same parts as in FIG. 3, and L denotes a distance between the small-diameter strap ring 3 and the large-diameter strap ring 4. The structure of the magnetron anode body of this embodiment is similar to the structure shown in FIG. 3, in which a plurality of vanes 2 are brazed radially to the inner peripheral surface of the anode cylinder 1 at the root thereof. A small-diameter strap ring 3 and a large-diameter strap ring 4 for connecting every other vane 2 are brazed into a strap ring groove provided in the vane. FIG. 1 shows one of the vanes. In this structure, the strap rings 3 and 4
This is to stabilize the π-mode oscillation by connecting the vanes 2 having the same potential every other sheet, and it is effective to connect them at a high potential. It is desirable that the small-diameter strap ring is closer to the tip of the vane 2. However, due to the processing problem of forming a concave groove 6 for disposing the strap ring at the tip of the vane (usually formed simultaneously with punching and molding of the vane with a die), the distance M from the tip is usually limited to It is formed to a thickness of about 2 to 4 mm, and in this embodiment, it is formed to be about 2.8 mm. Conventionally, the position of the large-diameter strap ring is determined in view of miniaturization, and the distance L between the large-diameter strap ring and the small-diameter strap ring is set to about 0.6 to 0.8 mm, but is set to 1 mm or more in this embodiment. In addition, 8 of this embodiment
When a magnetron having an oscillation frequency of 2450 MHz is used as the divided anode, the length N of the vane 2 is about 12 mm, and the width P of the strap ring is about 0.6 to 1.0 mm. In the present embodiment, the material of the small-diameter strap ring 3 is made of oxygen-free copper containing zirconium (0.005 to 0.3% by weight of zirconium, the balance being oxygen-free copper), and the large-diameter strap ring, which is another component of the anode body. 4. The material of the anode cylinder 1 and the vane 2 is oxygen-free copper. That is, since the small-diameter strap ring is brazed to the tip of the vane, it is necessary to maintain mechanical strength by using oxygen-free copper containing zirconium. The inventors of the present invention have conducted intensive studies from the viewpoint that the diameter can be kept low, and as a result, the small-diameter strap ring uses oxygen-free copper containing zirconium and is brazed to the vane tip side in the same manner as before, and the large-diameter strap ring has a large diameter. By arranging the large-diameter strap ring at a distance of 1 mm or more from the small-diameter strap ring, it has been found that the large-diameter strap ring made of only oxygen-free copper does not break. It is known that the oscillation frequency of a magnetron having a resonator composed of a collection of small cavities fluctuates by about several tens of MHz when the strap rings 3 and 4 fluctuate greatly or break. Therefore, the present inventors used oxygen-free copper containing zirconium for the small-diameter strap ring 3,
Oxygen-free copper is used for the large-diameter strap ring 4 and the like, and the position of the small-diameter strap ring 3 is changed variously without changing the position of the small-diameter strap ring 3 (see FIG. 1). L) is 0.6 mm, 0.8
Five types of magnetrons (all oscillation frequencies were adjusted to 2450 MHz) of mm, 1.0 mm, 1.2 mm, and 1.4 mm were manufactured, and an operation test was performed under severe conditions, and a time when an oscillation frequency shift occurred was examined. The operating conditions were as follows: the magnetron was mounted on a microwave oven and turned on for 2 minutes in a state near no load (large reflected power returned to the magnetron because microwaves were not absorbed, and the temperature at the tip of the vane was likely to rise).
The device was operated under the condition of giving an OFF heat shock for 1 minute. FIG. 2 shows the results of examining the time when the oscillation frequency changes by 10 MHz by repeating this operation. FIG.
In the graph, the horizontal axis indicates the distance between the small-diameter strap ring 3 and the large-diameter strap ring 4, and the vertical axis indicates the oscillation frequency of 10 MHz
z changes (ie the strap ring breaks)
Indicates the time until. As shown in FIG. 2, when the distance between the strap rings is 0.6 to 0.8 mm, the wider the distance, the longer it takes to break the strap ring, but becomes constant when the distance between the strap rings is 1 mm or more. . This is because the distance between the strap rings is 1mm
Until the large-diameter strap ring 4 is damaged and the oscillation frequency changes, the distance between the strap rings is 1 mm.
It has been found that the above causes the small-diameter strap ring 3 to be damaged. This operating condition is performed under severer conditions than the operating condition in a normal microwave oven, which leads to breakage of the small-diameter strap ring. However, in the normal operation, the small-diameter strap ring 3 made of zirconium-containing oxygen-free copper is not damaged. Also, the large-diameter strap ring 4 made of oxygen-free copper does not cause large deformation or breakage by arranging the small-diameter strap rings at an interval of 1 mm or more. When the small-diameter strap ring is formed of oxygen-free copper, a deviation of the oscillation frequency of 10 MHz occurs in about 80 hours regardless of the interval between the strap rings. As described above, the small-diameter strap ring 3 is formed of oxygen-free copper containing zirconium, and the large-diameter strap ring 4 is formed of oxygen-free copper, and the distance between the two large and small strap rings is 1 mm or more. In this case, there is no fluctuation in the strap ring, the reliability and durability of the magnetron are increased, and an inexpensive magnetron that can cope with high output and high temperature can be obtained. According to the present invention, only a small-diameter strap ring that is apt to break before a large-diameter strap ring in operation under high output is made of oxygen-free copper containing zirconium having excellent mechanical strength. Other members, such as large-diameter strap rings, are made of inexpensive and highly conductive oxygen-free copper, and the large-diameter strap rings are separated from each other so that the distance between them is 1 mm or more. With sufficient durability and oscillation efficiency,
Oxygen-free copper, which is inexpensive and has good workability, can be used as the large-diameter strap ring, so that the cost can be reduced. As a result, a magnetron that is inexpensive and can handle high output can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially enlarged sectional view of one embodiment of a magnetron anode body of the present invention. FIG. 2 shows the relationship between the distance between the strap rings and the time required for the oscillation frequency to reach 10 MHz in severe operation of a magnetron in which a small-diameter strap ring is formed of oxygen-free copper containing zirconium and a large-diameter strap ring is formed of oxygen-free copper. It is a figure showing a relation. 3A and 3B are explanatory views of a magnetron anode body, wherein FIG. 3A is a plan view and FIG. 3B is a cross-sectional view taken along line AA of FIG. [Description of Signs] 1 Anode cylinder 2 Bain 3 Small diameter strap ring 4 Large diameter strap ring

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01J 23/18-23/22

Claims (1)

(57) [Claims 1] An anode cylinder, a plurality of vanes radially arranged on the inner peripheral surface of the anode cylinder, and every other vane are electrically connected. A magnetron anode body comprising a large diameter strap ring and a small diameter strap ring, wherein the large diameter strap ring is made of oxygen-free copper, the small diameter strap ring is made of oxygen-free copper containing zirconium, and the large diameter strap ring is made of A magnetron anode body arranged with a gap of 1 mm or more with respect to the small diameter strap ring.