JPH0410331A - magnetron - Google Patents

Abstract

PURPOSE:To make a magnetron small lower its noise by setting at least one cooling fin composed of plates extended rectangularity to the axis of a cylindrical anode in both sides of the cylindrical anode in the way that the outer surface of the cylindrical anode is firmly fastened by fixing the fins to each other on both sides of the cylindrical anode. CONSTITUTION:At least one cooling fin 6 extended rectangularity to the axis of a cylindrical anode is so set on each of both sides of the cylindrical anode as to fasten the outer plane of the cylindrical anode firmly by fixing the fins one another by rivets, screw fittings, or welding. Consequently, heat generated by the operation of the magnetron is transmitted to the cooling fin through the firmly bound outer walls 8 of the cylindrical anode and the cooling fin 6 owing to thermal conduction and transferred and moved away by cooling wind from the surface of the cooling fin 6 which is relatively long transversely. As a result, electronic apparatus using the magnetron is made small and its noise is lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetron suitable for use in microwave ovens, etc., which is small and thin as a whole including cooling fins, and requires low cooling air pressure.

[Prior Art] During operation, the temperature of a magnetron rises, but if the temperature becomes too high, gaps such as a decrease in electron emission from the cathode occur.

Therefore, means are usually provided for externally cooling the anode cylinder.

In the case of microwave ovens, which have been widely used in recent years, since it is necessary to be easy to handle, liquid cooling is avoided and air cooling is adopted. figure(
Conventional example (for example, JP-A-59-186) showing the front view in b)
233), the cooling fins are press-fitted onto the outer periphery of the anode cylinder, and the cooling fins are force-fitted, and the cooling air is forced into the air passage between the anode cylinder and the yoke at right angles to the axis of the anode cylinder using a blower. Therefore, it was customary to cool the cooling fins to perform forced air cooling. In this way, since the cooling fins are arranged inside the yoke, the planar external dimensions of the magnetron are much larger than the anode cylinder diameter in any direction, as seen in Figures 4(a) and (b). growing. On the other hand, since the cooling air path is limited between the anode cylinder and the yoke as mentioned above, the wind pressure to flow the cooling air is high, and the flow velocity must also be relatively high, so High wind noise occurs. Noise is generated not only at the cooling fins of the magnetron, but also at the blower side. In FIG. 4, 1 is an anode cylinder, 2 is a permanent magnet, 3 is a yoke, 4 is a cooling fin, and 5 is an output section.

[Problems to be Solved by the Invention] In recent years, microwave ovens have become more diverse, and there is an increasing demand for smaller and quieter microwave ovens.

In order to meet this demand, conventional magnetrons are generally too large for the volume of the microwave oven, and the forced air cooling type is too noisy, making them difficult to use late at night when everyone is asleep. Such problems were occurring.

As a countermeasure to the above-mentioned problem, the method shown in Fig. 3 (a) has traditionally been used.
) As shown in the top view, and as shown in the front view in FIG. If such cooling fins are used, it becomes possible to make the microwave oven even more compact by taking advantage of the thinness of the magnetron, and to reduce the area of the cooling fins. Due to the larger size, there is no problem even if the cooling air speed and blowing pressure are low, which reduces the wind noise generated at the cooling fins, and the blower itself can be smaller and generate less noise.

However, the cooling fin itself used in the above-mentioned conventional solution is made of an extruded aluminum block with some machining, as shown in the top view in Figure 2 (a) and the front view in Figure 2 (b). We are the ones who made it.

The problem was that it was expensive. Safety and low prices are extremely important for household electronic equipment, and high prices are a major problem.

An object of the present invention is to provide a magnetron having a structure that can obtain the same effects as the above-mentioned conventional small-sized low-noise product using horizontally long cooling fins and can be manufactured at low cost.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a permanent magnet that forms a static magnetic field in the axial direction of the anode cylinder around the anode cylinder and the central cathode thereof, and a permanent magnet that forms a static magnetic field in the axial direction of the anode cylinder. In a magnetron equipped with a yoke surrounding the anode cylinder to form an external magnetic circuit, one or more cooling fins made of plate material each extending perpendicularly to the axis of the cylinder are placed between the anode cylinder and the fins on both sides of the anode cylinder. By fixing them together with rivets, screws, or welding, it was decided to arrange the anode so that the outer surface of the anode cylinder was closely tightened. Furthermore, when fixing the cooling fins on both sides of the anode cylinder to tightly tighten the outer surface of the anode cylinder,
The positions at which they are fixed and the shapes of the members therein are such that the cooling fins are in close contact with the outer surface of the anode cylinder and are elastically deformed following the thermal expansion of the anode cylinder.

The cooling fins are made of a plate made of a material with good thermal conductivity, such as aluminum, and are approximately semicircular at the point where they are brought into close contact with the anode cylinder.
In addition, in order to increase the surface area and improve the cooling performance, the parts where heat exchange is to be performed are formed in advance by press working, etc. so as to have irregularities. As mentioned above, following the expansion of the anode cylinder with a large temperature rise, the parts that are in close contact with the outer surface of the cylinder must undergo elastic deformation. For example, insert a washer or leave a distance between the fixed point and the anode cylindrical wall to reduce the amount of bending of the member in between, so that it acts like a leaf spring.

[Function] With the above method, the heat generated by the operation of the magnetron is transferred to the cooling fin by heat conduction through the contact surface between the outer wall of the cylinder of the five anodes and the cooling fin, and is transferred by the cooling air from the relatively long surface of the cooling fin. be carried away. Since the surface area of the cooling fins is larger than that of the conventional cooling fins, which have a nearly square planar shape as shown in Figure 4, the speed of the cooling air can be made relatively slow, reducing the noise caused by wind blowing. . Furthermore, since a cooling blower with low wind pressure can be used, the noise of the blower itself is also reduced.

Therefore, if a magnetron is properly designed to be installed in an electronic device using a magnetron, such as a microwave oven, the entire device can be made smaller and have lower noise levels.

[Example] FIG. 1(a) is a plan view of a cooling fin according to an example of the present invention.
Figure (b) shows its front view, and the magnetron main body is also shown by broken lines. The cooling fins are press-formed parts using an aluminum plate material with a Fl thickness of 0.3wn or more and 1.3I or less, for example, 0.5wIn. In the example shown in this figure, 4
The number of sheets used is determined by the amount of cooling air and the amount of heat generated by the magnetron anode.

The central part is shaped to match the dimensions of the yoke and the permanent magnet (not shown), but the cooling air sent in the axial direction of the anode cylinder is blocked by the above member and does not directly hit this part. Therefore, cooling is performed in a horizontally extending portion where the cooling fins are not in the shadow of the yoke, so the effective area of this portion is made as large as possible. In order to tightly tighten the cooling fins to the anode cylinder, spring washers and screws are used to tighten the cooling fins in this embodiment, but eyelets may also be used. In the parts that exchange heat with the cooling air, many small protrusions are formed by press working to increase cooling efficiency. In FIG. 1, 6 is a cooling fin, 7 is a small protrusion, 8 is an anode cylinder tightening part, and 9 is an eyelet. In addition, when the heat dissipation part corresponding to the cooling fin is also used as a microwave oven component, the heat conduction part is closely tightened to the outer surface of the anode cylinder according to the present invention, and the heat dissipation fin part is replaced by the above-mentioned microwave oven component. .

The easiest way to secure multiple cooling fins is with spring washers, bolts, and nuts. The spring washer is necessary to keep the cooling fin in close contact with the anode cylinder under appropriate pressure against thermal expansion and deformation of the anode cylinder. Another method is to use eyelets to fix the anode cylinder, but a part of the cooling fin acts like a leaf spring against the expansion and contraction of the anode cylinder, and the contact between the cooling fin and the anode cylinder is always pressurized. Decide the dimensions of the cooling fins so that they can be fixed with elasticity.

In one embodiment, by using the cooling fin according to the present invention, the magnetron's cooling capacity was reduced to half that of the conventional magnetron, and the cooling air noise during operation was reduced to about 1/10.

[Effects of the Invention] As described above, according to the present invention, electronic equipment using a magnetron can be made smaller and have lower noise.

[Brief explanation of the drawing]

FIG. 1(a) is a plan view of a cooling fin according to an embodiment of the present invention;
Figure 1 (b) is its front view, Figure 2 (a) is a top view of the conventional improved cooling fin, Figure 2 (b) is its front view, and Figure 3 (a) is the cooling fin. Figure 3 is a top view of a conventional thin magnetron in which the magnetron is stretched in a specific direction and thinned in the orthogonal direction.
b) is its front view, FIG. 4(a) is a top view of a conventional general magnetron, and FIG. 4(b) is its front view. 1...Anode cylinder, 2...Permanent magnet, 3...Yoke, 4...Cooling fin, 5...Output section, 6
...Cooling fin, 7. Small protrusion, 8. PIh pole cylindrical tightening part, 9. Eyelet. Fig. 1 (b) 6-'Gaku f-p fin 9-Masatome (b) ■--- Fig. (bl 1-day Oke Gojiishi yoke (b)

Claims (1)

[Claims] 1. In a magnetron equipped with an anode cylinder, a permanent magnet that forms a static magnetic field in the axial direction of the anode cylinder around a cathode at its center, and a yoke that surrounds these and forms an external magnetic circuit, the anode cylinder is sandwiched. Then, on each side, one or more cooling fins made of plate material extending perpendicularly to the cylinder axis are fixed to each other by rivets, screws, or welding, so that the outer surface of the anode cylinder is tightly attached. A magnetron characterized by being arranged in a tight manner.