JPH0765732A - Magnetron anode body - Google Patents

Abstract

PURPOSE:To improve the durability of a vane for maintaining the reliability thereof and restrain cost, so that a magnetron anode body can cope even with high temperature operation due to the application of a high output system. CONSTITUTION:Vanes 2 are radially arrayed on the internal surface of an anode cylinder 1. Strap rings 3 having a small diameter and strap rings 4 having a large diameter for connecting every other vanes 2 are jointed to the axial ends thereof, and at least the rings 3 are formed out of an allay of silver and oxygen free copper.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to magnetron anode bodies. More specifically, the present invention relates to an anode body of a magnetron in which the strap ring is not damaged by heat even when the output of the magnetron is increased.

[0002]

2. Description of the Related Art A magnetron anode generally used in a microwave oven has a structure as shown in FIG.

That is, in FIG. 1, (a) is a plan view and (b) is a sectional view taken along the line AA of (a). The anode bodies are radially arranged on the anode cylinder 1 and its inner peripheral surface. It is composed of even numbered vanes 2, and a small-diameter strap ring 3 and a large-diameter strap ring 4 in which every other one of the vanes 2 is connected. Strap rings 3 and 4 are bain 2
There are cases where it is provided only on one end side in the axial direction of, and there are cases where it is provided at both axial ends of the vane 2 as shown in FIG. It is common to connect the vanes of. With 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 thereof forms a resonance cavity of the magnetron. Since the magnetron normally oscillates in the π mode, each small cavity 5 oscillates with a phase shift of π radian. for that reason,
In order to stabilize the oscillation of the magnetron, every other vane is connected by the small diameter and large diameter strap rings 3 and 4 so as to have the same potential.

A pair of magnetic pole pieces (not shown) are arranged at both open ends of the anode cylinder 1, and on the central axis of the anode cylinder 1.
A magnet (not shown) for forming an orthogonal electrostatic magnetic field together with a high voltage applied to a working space between the vane 2 and a cathode (not shown) provided at a portion of the vane 2 facing the tip 2a. Form a magnetic field.

Oxygen-free copper, which has good heat conduction and electric conduction and has little gas emission, is generally used as a material for forming the anode body of the magnetron having such a structure. However, the tip 2 of the vane 2 near the cathode in the anode body 2
Since the strap rings 3 and 4 provided on the a portion and the tip portion of the vane 2 are likely to become hot, and 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 and bending is likely to occur with repeated use, and eventually breaks. Since the resonance frequency of each small cavity is determined by the capacitance (C) between the strap rings, the capacitance (C) between the strap ring and the vane, the vane inductance (L), etc., the strap ring may be broken, When it is deformed, the resonance frequency changes, which in turn changes the oscillation frequency. Further, when the strap ring is cut, the purpose of the strap ring of connecting the vanes of the same potential to stabilize the oscillation cannot be achieved, and the magnetron characteristic is deteriorated.

[0006] On the other hand, in recent years, there is a tendency for the cooking capacity of microwave ovens to improve.
There is also a movement to output W, and even 1000 W. With such an increase in output, research on magnetron materials that can withstand high temperatures is being promoted.

As such a material, for example, Japanese Patent Laid-Open No.
As described in Japanese Patent No. 121932, it has been proposed to use zirconium-added precipitation hardenable metal having improved mechanical strength for a strap ring or the like.

[0008]

However, the aforementioned 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, etc., but zirconium-containing oxygen-free copper has poor wettability to silver brazing material which is a brazing material, which reduces the efficiency and reliability of brazing work. There's a problem.

According to the present invention, the conductivity is enhanced by using oxygen-free copper containing silver instead of using oxygen-free copper containing zirconium, which is expensive and deteriorates in electrical characteristics, for a small-diameter strap ring which is apt to become hot. An object of the present invention is to provide a highly reliable magnetron anode body which has good wettability to silver brazing material which is a brazing material and retains mechanical strength, and can cope with high output and high temperature of microwave ovens and the like. And

[0010]

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 an electric wire for every other vane. A magnetron anode body comprising a large diameter strap ring and a small diameter strap ring connected to
The small diameter strap ring is made of an alloy of silver and oxygen-free copper.

The alloy of silver and oxygen-free copper has a silver content of 0.025-0.
It is preferably an alloy containing 3% by weight.

[0012]

According to the present invention, at least the inner small-diameter strap ring is made of an alloy of silver and oxygen-free copper.
Even if the temperature of the small diameter strap ring becomes high, it is possible to obtain sufficient mechanical strength. Moreover, since the conductivity can be maintained high, the electrical characteristics are not impaired.

That is, the alloy of silver and oxygen-free copper has higher mechanical strength than oxygen-free copper, is less likely to cause breakage or deformation of the strap ring, and has a conductivity of 100% IACS (International Annealed Copper Standard, In
ternational Annealed Copper Standard, volume resistivity 1
The conductivity of 7.24 nΩ · m international standard annealed copper wire is 100%), which is almost the same as 102% IACS of oxygen-free copper, and the wettability of brazing material to silver is also wettable to oxygen-free copper. Since there is almost no difference, the adhesive strength is strong with less brazing material. As a result, high characteristics and high reliability can be maintained.

[0014]

The present invention will be described in detail with reference to the drawings.

Similar to the structure shown in FIG. 1, the magnetron anode body of the present embodiment has a plurality of vanes 2 radially brazed at its root on the inner peripheral surface of the anode cylinder 1. Further, a small-diameter strap ring 3 and a large-diameter strap ring 4 that connect every other one of the vanes 2 are brazed in a groove for a strap ring provided in the vane 2.

With this structure, the strap rings 3 and 4 are 1
This is for stabilizing the π-mode oscillation by connecting the vanes 2 having the same potential every other sheet, and it is effective to connect the vanes 2 at a high potential, and it is desirable that the small diameter strap ring 3 is closer to the tip of the vane 2. However, due to a processing problem of forming a concave groove 6 (usually formed at the same time when the vane is punched by a die) for arranging the strap rings 3 and 4 at the tip of the vane 2, usually from the tip. The distance M is 2
The thickness is about 4 mm, and also in this embodiment, it is about 2.8 mm. As described above, since the cathode is placed in the center of the anode cylinder surrounded by the tip of the vane 2 and the temperature is about 1700 ° C., the radiant heat and the bombardment of electrons from the cathode make the tip of the vane extremely High temperature (eg
Some heat is conducted to the anode cylinder 1 and is released to the outside from the outer peripheral wall of the anode cylinder 1, but the thermal gradient is large and the magnetron is turned on and off.
The strap ring is likely to break due to the thermal stress associated with the FF.

We have found that the strap ring breaks,
As a result of extensive studies to suppress deformation, the use of an alloy of silver and oxygen-free copper for the material of the small diameter strap ring 3 which tends to increase the temperature particularly improves the strength of the strap ring and prevents breakage or deformation. It has been found that the conductivity can be maintained high, the strap ring function can be sufficiently exhibited, and a magnetron with high characteristics can be obtained.

The inventors of the present invention have further made earnest studies as to the appropriate range of the silver content of the alloy of silver and oxygen-free copper, and as a result, the higher the silver content, the higher the strength. It has been found that the strength is improved, which is preferable, but when the amount is too large, the conductivity is lowered, which is not preferable, and it is suitable that the silver content is in the range of 0.025 to 0.3% by weight. That is, the present inventors manufactured a magnetron using an alloy of silver and oxygen-free copper having various silver contents as the small-diameter strap ring 3, and investigated the time when the deviation of the oscillation frequency reached 10 MHz by using a machine. I examined the physical strength. The reason for adopting this method is that the oscillation frequency is 10 MHz if the strap ring fluctuates or is damaged in the magnetron.
~ It is known to vary by several tens of MHz. for that reason,
For example, it is indicated that the earlier the time when the oscillation frequency shift of 10 MHz occurs, the easier the deformation of the strap ring. 10 vanes, oscillation frequency 2450MHz, output
Fig. 2 shows the results of investigating the time when the oscillation frequency shifts by 10 MHz by changing the silver content of the small diameter strap ring with a 1200 W magnetron. The operating condition of the magnetron at this time is to turn it on for 2 minutes when the magnetron is attached to a microwave oven and the load is close to no load (a large reflected power returns to the magnetron because microwaves are not absorbed and the temperature at the tip of the vane easily rises). This is a condition for giving a heat shock of OFF for 1 minute (estimated temperature of the small diameter strap ring 3
(Constant at 370 ℃). As is clear from FIG. 2, when the silver content is 0.025% by weight or more, the strength of the small diameter strap ring is rapidly improved. Further, when the content of silver exceeds 0.3%, the electrical conductivity becomes low, so that it was not manufactured. As a result, in the range of 0.025 to 0.3% by weight, the mechanical strength was improved and the electrical characteristics were not deteriorated.

On the other hand, as the output increases, the vane 2
Although the temperature of the tip of the small diameter strap ring 3, that is, the temperature of the small diameter strap ring 3 also rises, the relationship between the temperature of the small diameter strap ring 3 and the time until the oscillation frequency shifts by 10 MHz is examined, and the result is shown in FIG. The temperature of the small diameter strap ring 3 is measured on the assumption that there is a constant thermal gradient between the axial center side of the vane 2 and the anode cylinder 1 side. The temperature of No. 3 was estimated (for example, about 170 ° C. higher than that of the anode cylinder 1), and the temperature of the anode cylinder 1 was changed by a blower to change the estimated temperature of the small diameter strap ring 3. In FIG. 3, the small diameter strap ring is also shown in comparison with the conventional example B in which the oxygen-free copper is still used. As is clear from FIG. 3, compared to the conventional example
It has improved about 1.4 times.

Further, the number of vanes is 8 and the oscillation frequency is
Similarly, with respect to the 2450 MHz magnetron, the change in time when the oscillation frequency was shifted by 10 MHz was examined for 1200 W, and similar results were obtained.

Since the above operating conditions are performed under severer conditions than the operating conditions in a normal microwave oven, the small-diameter strap ring 3 is damaged, but in normal operation, the small-diameter strap made of an alloy of silver and oxygen-free copper is used. The strap ring 3 is not damaged.

In the above description, only the small-diameter strap ring 3 is made of an alloy of silver and oxygen-free copper, but the large-diameter strap ring 4 and the vanes 2 are not made of silver having a silver content of 0.025 to 0.3% by weight. It is also possible to use an oxygen copper alloy, which results in a more reliable magnetron anode body.

As described above, by forming at least the small-diameter strap ring 3 from an alloy of silver and oxygen-free copper, the strap ring does not fluctuate, the reliability and durability of the magnetron are increased, and high output and high temperature are achieved. It is possible to obtain an inexpensive magnetron that can be used for various purposes.

[0024]

According to the present invention, a small-diameter strap ring which easily breaks prior to a large-diameter strap ring during operation under high power is provided with silver and oxygen-free material having excellent mechanical strength and high conductivity. By forming with a copper alloy,
Sufficient durability and oscillation efficiency can be obtained even with high output of the magnetron. As a result, it is possible to obtain a magnetron that is inexpensive and can handle high output.

[Brief description of drawings]

FIG. 1 is an example of a magnetron anode body, (a) is a plan view and (b) is a cross-sectional view taken along line AA of (a).

[Fig.2] Oscillation frequency is 10MHz when the content of silver is changed by using an alloy of silver and oxygen-free copper for the small diameter strap ring.
It is a figure which shows the relationship of the time until it shifts.

FIG. 3 is a diagram showing the relationship between the estimated temperature of the small diameter strap ring and the time until the oscillation frequency shifts by 10 MHz.

[Explanation of symbols]

 1 Anode cylinder 2 Bain 3 Small strap ring 4 Large strap ring

Claims (2)

[Claims] 1. An anode cylinder, a plurality of vanes radially arranged on an inner peripheral surface of the anode cylinder, and a large-diameter strap ring and a small-diameter strap ring electrically connecting every other vane. A magnetron anode body comprising the strap ring, wherein at least the small diameter strap ring of the strap rings is made of an alloy of silver and oxygen-free copper. 2. The alloy of silver and oxygen-free copper has a silver content of 0.025.
The magnetron anode body according to claim 1, wherein the magnetron anode body is an alloy containing about 0.3% by weight.