JPH088067B2 - Magnetron - Google Patents

Description

TECHNICAL FIELD The present invention relates to a magnetron used in microwave heating equipment such as a microwave oven.

2. Description of the Related Art A magnetron used in a microwave heating device such as a microwave oven is usually constructed as shown in FIG. 4, and a copper cylindrical anode cylinder 1 is provided with a cathode 2 from its inner peripheral surface.
A pair of funnel-shaped magnetic pole pieces for magnetic field concentration 4, 5 having a plurality of anode vanes 3 projecting toward the front end are incorporated in the upper and lower opening edges of the anode cylinder 1. On the outer peripheral surface of the anode cylinder 1,
A large number of heat radiation plates 6 made of aluminum or its alloy are attached in multiple stages, and these heat radiation plates 6 form a radiator.
Has a hole 6a in the central region for press-fitting the anode cylinder 1,
The hole 6a has a short tubular portion 6b integrally protruding from the peripheral edge thereof. The annular permanent magnets 7 and 8 that are coaxially stacked on the outer end surfaces of both the pole pieces 4 and 5 constitute an external magnetic circuit together with the frame yoke 9, and A choke coil 11 for an LC filter circuit is connected to a cathode terminal lead wire 12 in a shield case 10 attached to the outer surface of the bottom plate portion. 13 indicates a microwave output terminal.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the magnetron configured as described above, the short cylindrical portions 6a of the large number of heat dissipation plates 6 are in close contact with the outer peripheral surface of the anode cylinder 1, and the space between the heat dissipation plates 6 is in operation. Since the forced air cooling airflow circulates, the danger that the anode cylinder 1, the pole pieces 4,5, the permanent magnets 7, 8 and the like will become hot during operation is prevented, and
It is possible to prevent the coercive force from declining with the temperature rise of the permanent magnets 7, 8.

However, the degree of contact between the anode cylinder 1 and the short cylindrical portion 6b decreases as the magnetron is used for a long period of time. This is because the inner diameter of the short tubular portion 6b that has been plastically deformed by press-fitting the anode cylinder 1 gradually expands with repeated thermal expansion and contraction of the anode cylinder 1.
There is a risk that the degree of mechanical and thermal degree between the anode cylinder 1 and the heat dissipation plate 6 will gradually decrease, and especially the middle region of the anode cylinder 1 will have an abnormally high temperature. Therefore, it is conceivable to further increase the degree of fitting between the anode cylinder 1 and the short tubular portion 6b. However, if such a configuration is adopted, not only the press-fitting will not be easy, but especially the middle part of the anode cylinder 1 The pressure equalizing ring (not shown) that bends inward and short-circuits every other one of the many anode vanes 3 is deformed or broken, resulting in a change in resonance characteristics.

Means for Solving the Problems The present invention has been made to solve the above conventional problems, and according to the present invention, the outer diameter of the middle region of the anode cylinder is larger than the outer diameters of both side regions sandwiching the same region. Egg it small. And
The both side regions are in contact with the short tubular portion surrounding the same region in the conventional manner, while the middle abdominal region is in contact with the short tubular portion surrounding the same region in a loose manner. However, the both side regions,
While closely contacting the short tubular portion surrounding the same region, the inner diameter of the short tubular portion surrounding the middle abdominal region is formed larger than the inner diameter of the short tubular portion surrounding the both side regions, The area may be in contact with the short tubular portion surrounding the area and loosely.

Operation With this structure, the anode cylinder until thermal expansion is in intimate contact with the short tubular part of the heat dissipation plate only in the regions on both sides, but the anode cylinder after thermal expansion is In any of the both side regions and the middle region, it comes into close contact with the short tubular portion of the heat dissipation plate. That is, since the middle abdominal region that first increases in diameter after the magnetron starts operating, it comes into intimate contact with the short tubular portion of the heat dissipation plate corresponding to the region, so that the intermediate region becomes irreversible. It is possible to prevent or reduce the time-dependent change that is being expanded. Further, the work of press-fitting the anode cylinder into the holes of the large number of heat dissipation plates becomes easy. Incidentally, the short tubular portion surrounding both side regions of the anode tubular body serves as a stopper in contact with the short tubular portion surrounding the middle abdominal region, so that the heat dissipation plate corresponding to the middle abdominal region is at room temperature, While being supported by the short tubular part,
Both sides will be supported by both side walls of the frame yoke.

EXAMPLES Next, the present invention will be described in detail with reference to the examples shown in the drawings.

The configuration shown in FIG. 1 differs from the conventional configuration shown in FIG. 4 in that the outer diameter A of the middle abdominal region of the cylindrical anode cylinder 14 made of copper, that is, the middle abdominal region 14a shown in FIG. A point smaller than the outer diameter B of the side regions 14b, 14c, and a large number of heat sinks stacked in multiple stages in contact with both side walls of the yoke to form a radiator in the frame yoke. Those located on both sides of 6 have their short tubular portions 6b in close contact with both side regions 14b and 14c of the anode tubular body, respectively, as shown in part in FIG. The short tubular part 6b
Is loosely in contact with the middle region 14a of the anode cylinder, and other configurations are the same. The middle region 14a occupies a position corresponding to the anode vane 3.

The difference between the outer diameter A and the outer diameter B is exaggerated in the drawing, but is actually small. Assuming that the inner diameter (before press-fitting of the anode cylinder) of each short cylinder portion 6a of the large number of heat dissipation plates 6 forming the radiator is C, the relational expression of A <C <B should be satisfied at room temperature.

In the above-described embodiments, the difference between the outer diameter of the middle region of the anode cylinder and the outer diameter of both side regions is provided, but the inner diameter of the short tubular portion of the heat dissipation plate may be provided. That is, the both side regions of the anode cylinder are closely contacted with the short cylinder part surrounding the same region as in the conventional case, but the inner diameter of the short cylinder part surrounding the middle region of the anode cylinder surrounds the both side regions. It is formed to be larger than the inner diameter of the short tubular portion and is loosely contacted with the middle abdominal region. In this case, it is not necessary to provide the outer diameter of the anode tubular body with the difference as described above.

Effects of the Invention As described above, according to the present invention, the middle region of the anode cylinder closely contacts the heat dissipation plate as the temperature of the region increases. It is possible to prevent an increase in size and always obtain a good heat dissipation effect.

[Brief description of drawings]

FIG. 1 is a side sectional view of a magnetron embodying the present invention, FIG. 2 is an enlarged side sectional view of an essential part of the magnetron, FIG. 3 is a perspective view of the essential part, and FIG. 4 is a side of a conventional magnetron. FIG. 2 ... Cathode, 4,5 ... Pole piece, 6 heat sink, 6a ... Hole, 6b
...... Short tube magnetic part, 9 ...... Frame yoke, 14 ...... Anode cylinder, 14a
...... Middle region, 14b, 14c ...... Both sides region.

Claims (2)

[Claims] 1. A radiator for cooling an anode cylinder comprises a large number of radiator plates stacked in multiple stages in a frame-like yoke in contact with both side walls of the yoke, and each radiator plate is the anode cylinder. Has a short tubular portion that surrounds the anode cylinder at the periphery of a hole that penetrates the anode cylinder, and the outer diameter of the middle region of the anode cylinder is smaller than the outer diameter of both side regions sandwiching the same region, and the both side regions are A magnetron, wherein the magnetron is in close contact with a short tubular portion surrounding the same region, and the middle region is loosely in contact with a short tubular portion surrounding the same region. 2. A radiator for cooling an anode cylinder comprises a large number of heat sinks stacked in multiple stages in a frame-like yoke in contact with both side walls of the yoke, and each radiator plate is the anode cylinder. Has a short tubular portion that surrounds the anode cylinder at the periphery of a hole that penetrates, and both side regions that sandwich the middle region of the anode cylinder closely contact with the short tubular portion that surrounds the region, and the middle region The magnetron characterized in that the short tubular portion surrounding the region has an inner diameter larger than that of the short tubular portions surrounding the both side regions and is in loose contact with the middle abdominal region.