JPH0545005Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a microwave electron tube, and particularly aims to improve its cooling capacity.

For example, magnetrons, which are often used in microwave ovens, use a large amount of electric power and therefore tend to heat up easily, and their cooling capacity determines their performance and lifespan. In general, a group of heat sinks with a sufficient heat dissipation area is attached so as not to degrade performance, so they are made larger accordingly. In addition, the main body parts are often made larger in anticipation of a decrease in strength when the temperature rises. Therefore, by increasing the cooling capacity,
The overall design will be smaller and lighter.

The cooling part of the electron tube is made of metal, and the heat generated here is quickly transferred to cooling air or water to prevent temperature rise. Therefore, the heat transfer ability of the heat transfer component that connects the air or water and the metal part of the electron tube becomes a problem. In other words, the metal parts of the electron tube and all heat transfer parts should be made of silver, which has the highest thermal conductivity. However, silver is expensive and lacks strength, so for example, the anode tube of a magnetron is made of copper.
The heat sink attached to this is generally made of aluminum (aluminum or its alloy). The heat sink may also be made of copper instead of aluminum. By the way, the thermal conductivity of conventional pure copper is 0.923 compared to 1.0 for silver, and 0.487 for aluminum. When both are alloyed with other metals, the thermal conductivity decreases. Conversely, the lower the amount of oxygen contained in copper, the higher the thermal conductivity.
Oxygen-free copper with ideally reduced oxygen reaches an even higher value of 1.06. In addition, the amount of oxygen in Toughpitu copper is 300~
400PPM, and even conventional oxygen-free copper has a concentration of 20 to 100PPM, but the above oxygen-free copper has a
It was lowered to 4PPM.

In this way, copper with a thermal conductivity higher than that of silver was obtained, but pure copper is not strong enough to be used as a component material. Materials alloyed with other metals to improve strength have a significantly lower thermal conductivity.

However, according to the inventor's research, only the recently developed iron phosphide precipitated copper alloy improves the strength of pure copper while maintaining a thermal conductivity of 1.04, exceeding silver in both strength and thermal conductivity. This is made by adding a small amount of iron to phosphorus-deoxidized copper, and its standard components are Fe0.10,
P0.034, remainder Cu. The material used in this invention has a thermal conductivity of around 1.04 and a tensile strength of 30 to 48.
It is deoxidized, solution treated, and precipitated so as to have a weight of Kg/mm ² , and is work hardened if necessary.

This invention targets an electron tube that has a group of heat sinks brazed or fitted together so as to stand at right angles to the outer periphery of the electron tube metal part or the intermediate cylinder fitted to the outer periphery. An iron phosphide precipitated copper alloy having the above-mentioned thermal conductivity and tensile strength is used for all of the group, or at least for the heat sink group. The thickness of the heat sink that corresponds to the external dimensions is at least a thickness that does not cause harmful deformation due to the brazing or fitting connection, and is less than half the normal thickness of an aluminum heat sink under the same conditions.

Next, embodiments of this invention will be described with reference to the drawings.

FIG. 1 shows an example of a conventional microwave oven magnetron to which this invention is applied. In this case, the anode tube 1 corresponds to the electron tube metal part for cooling mentioned above. The inner circumferential plate 3 of the second group of heat sinks corresponds to the above-mentioned intermediate cylinder. The heat dissipation plate 2 is made of aluminum and is brazed to the inner peripheral plate 3 at appropriate intervals to form a group, and then fitted onto the outer periphery of the anode tube 1 and brazed. Although this method is easier to manufacture, the heat dissipating plates 2 may be brazed directly to the anode tube 1 one by one. Alternatively, part or all of the brazed portion may be replaced by snap-fitting, such as shrink-fitting, cold-fitting, press-fitting, static fitting.

In the figure, 4 is the output antenna, 5 is the ferrite magnet,
6 is a magnetic yoke, 7 is a cathode, 8 is a shield case, 9 is a capacitor, and 10 is a chiyoke coil.

Figures 2 and 3 show an example of two groups of heat sinks according to this invention. In this embodiment, all the heat sinks 2 are joined to the intermediate tube 3', and this intermediate tube 3' can be fitted into the metal part of the electron tube, that is, in the case of the magnetron shown in FIG. 1, the outer periphery of the anode tube 1. ing. Both the intermediate tube 3' and the heat sink 2 are made of iron phosphide precipitated copper alloy. This material has twice the thermal conductivity and four times the strength of conventional aluminum. Therefore, with the same heat dissipation area, the thickness of the heat dissipation plate 2 can be reduced to half of the conventional one, and the same heat conduction ability as the conventional one and a greater heat dissipation ability can be obtained. In terms of strength, the thickness of the heat sink can be reduced to one-fourth, but if it is too thin, it will cause thermal distortion when soldered to the electron tube metal part or intermediate tube 3'.
If they fit together, the hole edges will stretch and become deformed, which may impede the flow of cooling air. Therefore, the thickness of the heat sink 2 of this invention is made thinner than the conventional one made of aluminum within a range that does not cause harmful deformation.
It is always possible to reduce the thickness to less than half the conventional thickness.

Note that the thickness of the heat sink 2 corresponds to its external dimensions, and it is natural that the thickness of the large plate is greater than the thickness of the small plate. Since the copper alloy heat sink 2 of this invention has excellent thermal conductivity and strength,
You can freely reduce the number of heat sinks with a large outer shape, or increase the number of heat sinks with a small outer shape to create a cluster of heat sinks that utilizes the thinness of the plates.

In addition, this copper alloy has high heat resistance with a softening temperature of 400°C, so it can be hard soldered with a much higher melting point than aluminum or solder.
A heat sink group with sufficient heat resistance can be obtained. It should be noted that the shape of the hole edges to be brazed in the heat sink 2 may be appropriately selected and utilized from conventional techniques. For example, as shown in FIG. 4, the well-known hole edge may be folded to serve as a gap spacer. This alloy has good brazing properties. In addition, it has good corrosion resistance and stress corrosion cracking resistance, and there is no risk of hydrogen embrittlement, so there is no problem even if it is exposed to cooling air containing kitchen smoke.

This idea is the first microwave electron tube to use an iron phosphide-precipitated copper alloy, which has been deoxidized, solution-treated, and precipitated to have better thermal conductivity and strength than silver, for electric heating components such as anode tubes and heat sinks. .

As is well known, the performance of a heatsink depends on its surface area, not its cross-sectional area.
The thickness can be reduced to a quarter of that of conventional aluminum heat sinks, and the thermal conductivity is twice as high, making it possible to create the best design for a group of heat sinks.

This invention has the great effect of improving the cooling capacity of microwave electron tubes, thereby improving their performance, reducing their size, and extending their lifespan by improving the strength and corrosion resistance of cooling parts.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of an example of a magnetron for a microwave oven, Fig. 2 is a front view of an embodiment of the heat sink group of the magnetron of this invention, Fig. 3 is a side view of the same, and Fig. 4 is a partial cross section of another embodiment. It is a diagram. 1... Electron tube metal part (anode tube), 2... Heat sink,
3...Intermediate tube (inner peripheral plate).

Claims (1)

[Scope of Claim for Utility Model Registration] In an electron tube having a group of heat dissipating plates brazed or fitted together so as to stand at right angles to the outer periphery of the electron tube metal part or the intermediate cylinder fitted to the outer periphery, At least the heat sink group of the cylinder and heat sink group has a standard composition of Fe0.10, P0.034, and the balance Cu, and is deoxidized, solutionized, precipitation treated, and work hardened as necessary to achieve a thermal conductivity of 1.04. The front and rear parts are made of iron phosphide precipitated copper alloy with a tensile strength of 30 to 48 kg/ ^mm2 .
A microwave electron tube characterized in that the thickness of the heat sink is a thickness that does not cause harmful deformation due to the brazing or fitting bonding, and is less than half of the normal thickness of an aluminum heat sink under the same conditions.