JPH0554807A - Magnetron - Google Patents

Abstract

PURPOSE:To enhance the mass productivity of the anode portion of a magnetron and to enhance the reliability thereof by joining a vane to an anode strap into predetermined configuration. CONSTITUTION:An anode strap 3a is stored in an anode-strap storage groove 5a notched in an overhanging portion 2b provided at the end of the vane 2a of an anode cylinder 1a and the vane-connecting radially-projecting portion 23a of the anode strap 3a is placed on the stepped level portion of the inside wall face of the storage groove 5a and the end face of the projecting portion 23a is fittingly joined to the inside wall face of the storage groove 5a. The width T1 of the circumferential end face of the projecting portion 23a of the anode strap 3a is therefore smaller than the width T2 of the inside wall face of the anode-strap storage groove 5a notched in the overhanging portion 2b provided at the end of the vane 2a and is almost the same as the radial wall thickness of the anode strap 3a. As a result, thermal stress generated at the anode strap with the temperature change of the magnetron caused as the magnetron is operated and stopped is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses only one type of pressure-equalizing ring, allows easy adjustment of the microwave oscillation frequency to a desired value, and is capable of repeating thermal deformation of the pressure-equalizing ring during operation and non-operation. The present invention relates to a magnetron suitable for use in a microwave oven, which has reduced mass damage due to fatigue and has good mass productivity and high reliability.

[0002]

2. Description of the Related Art FIG. 3 shows an example of a conventional magnetron generally used in a microwave oven or the like. In the figure, 1 is an anode cylinder, 2 is a vane, 3 is an inner pressure equalizing ring, 4 is an outer pressure equalizing ring, 5 is a pressure equalizing ring housing groove, 6 is an output conductor, and 7 is a metal exhaust pipe for exhausting the inside of the pipe and its An output conductor end portion which is cut off together with an output conductor passing therethrough in a vacuum-tight manner, 8 is an output portion that protects the output conductor end portion and radiates microwave power from the output conductor end portion to the outside, 9 is a cathode And the tip of the vane are in contact with the upper and lower ends of the anode cylinder at the peripheral edge of the flat annular surface portion to form an axial static magnetic field in the cylindrical working space, and from the annular surface portion to near the upper and lower ends of the operating space. A magnetic pole having a conical surface portion, 10 is an annular permanent magnet that is disposed in the vicinity of the annular surface portion of the magnetic pole and serves as a magnetomotive force source that forms the static magnetic field,
Reference numeral 11 denotes a yoke for magnetically coupling between the permanent magnets, which are divided into two parts in the axial upper and lower parts for convenience of assembly and are respectively arranged at the upper and lower ends of the anode cylinder, and 12 is a cathode surrounded by the vane tip through the working space. Reference numeral 13 is a cooling fin for air cooling which is fitted to the outer surface of the anode cylinder and dissipates heat generated in the anode to the outside during operation, and 14 is a groove for connecting the end portion of the output conductor to one of the vanes for connection. When the vane is extruded integrally with the anode cylinder, even if only one vane is actually connected to the output conductor, it is formed in all vanes because the groove is cut by the lathe work. Although the groove 14 has an extremely simple rectangular cross section, the pressure equalizing ring housing groove 5 has a step portion in the middle of the groove because both the inner and outer pressure equalizing rings are connected to every other vane. The width is wide and the width is narrow in the lower half.

FIG. 4 is a top view of the above-mentioned conventional anode cylindrical portion. In FIG. 4, reference numeral 23 indicates the inner pressure equalizing ring to be connected to every other vane, so that half of the vanes project radially inward. The connecting projections 24 are connecting projections that are radially outwardly projected to half of the vanes in order to connect the outer pressure equalizing rings to every other vane. Each is joined to a predetermined vane. Other signs are the same as those in the case of FIG. As shown in the drawing, the width in the circumferential direction of the end face connected to the vane of the vane connecting radial protrusion of the pressure equalizing ring is the same as the thickness of the vane,
Here, it is brazed and fixed to the vane with silver solder or the like. The structure of such a vane is, for example, the actual Kaisho 51
No. 1,149,962.

The portion surrounded by the anode cylinder 1 and the vane 2 respectively forms a cavity resonator. On the other hand, the outer anode cylinder is normally grounded for safety reasons, and a large negative potential is applied to the inner cathode. The electrons accelerated by being attracted from the cathode toward the anode are subjected to the Lorentz force orthogonal to the path due to the action of the static magnetic field acting at right angles to the movement direction, forming an electron cloud and orbiting in the action space. To do. In the cavity resonator group formed on the inner circumference of the anode cylinder by the orbiting electron cloud as described above, a high frequency oscillation having a phase difference of just π between adjacent resonators is induced during normal operation. The pressure equalizing ring electrically connects the locations where the voltages of the cavity resonators oscillating in the same phase should be in the same phase, thereby ensuring the so-called π-mode oscillation. If the respective cavity resonators are completely in the same state, the connection points between the pressure equalizing ring and each vane are always at the same potential, and no current flows in the pressure equalizing ring. However, as described above, the output conductor 6 is connected to only one vane in this example (for example, one for communication is connected to half of the vanes every other one), and it is unavoidable at the time of manufacturing. Because of the error, the resonators are not completely in the same state, so that a current actually flows through the pressure equalizing ring during operation.

[0005]

However, the above-mentioned conventional magnetron has a problem that the following drawbacks must be suppressed.

A: Two types of pressure equalizing rings are used, there are many joints between the pressure equalizing rings and the vanes, and there is a high probability that defective brazing will occur during the manufacturing process. When inspecting this, it is necessary to check both sides of the vane, the number of inspection steps is increased, and the defect oversight rate is increased. In addition, the circumferential width of the end face connected to the vane of the vane connecting radial protrusion of the pressure equalizing ring is designed to be the same as the thickness of the vane, and the end face of the protrusion of the pressure equalizing ring is just the thickness of the vane. It is not always easy to arrange them so that they overlap each other.

B: Since the pressure-equalizing ring and the vane are bonded and fixed to each other, the length of the freely deformable portion of the pressure-equalizing ring is reduced by that much. The damage of the pressure equalizing ring is more likely to occur (compared to the case where the width of the joint between the pressure equalizing ring and the vane is narrow) due to fatigue due to repeated thermal deformation during and without operation of the magnetron.

An object of the present invention is to solve the above-mentioned problems of the conventional magnetron, and to provide a magnetron with improved mass productivity of the anode part, high reliability, and excellent cost performance.

[0009]

In order to solve the above problems, in the present invention, a cavity resonator group is formed on the inner circumference of the anode cylinder by the anode cylinder and a plurality of vanes radially protruding from the inner wall thereof. In the magnetron, bulging portions that project symmetrically toward the tip side of both adjacent vanes are formed at the tips of each vane, and pressure equalizing ring storage grooves are vertically symmetrically formed on the axially upper and lower end surfaces of these bulging portions. Each of the grooves accommodates one equalizing ring having the same shape and size, in which radial projections for connecting vanes, which are half the number of vanes, are evenly distributed in the circumferential direction, and the end faces of the projecting portions of both equalizing rings are respectively described above. Electrically connected to the side wall surface of the groove, every other half of the vanes in one set are in the upper surface groove, and in every other half are the same in the lower surface groove. Connected to the equalizing ring It was so. In addition to doing this, the circumferential width of the end face connected to the vane of the vane connecting radial projection of the pressure-equalizing ring is set to be equal to or less than the circumferential wall thickness of the vane other than the projecting portion at the tip. It was reduced until it became equal to the radial thickness of the pressure equalizing ring.

[0010]

With the above means, it is only necessary to use one type of pressure equalizing ring, the number of joints between the pressure equalizing ring and the vane is halved, and the width of the joint between the pressure equalizing ring and the vane is reduced. Since it is decreased, the failure occurrence rate of the pressure-equalizing ring is reduced due to fatigue failure due to repeated thermal deformation during and without operation of the magnetron. Since the deformable region of the pressure equalizing ring is larger than that in the conventional case, it is easy to forcibly deform the pressure equalizing ring in the manufacturing process to adjust the resonance frequency. Further, since one equalizing ring is provided on each of the upper and lower axial end faces of the vane, the capacitance between the equalizing rings is reduced as compared with the conventional one, but since the protruding portion is provided at the tip of the vane, it is adjacent. The capacitance of these parts between the vanes is larger than the capacitance between the tips of the adjacent vanes of the related art, and the equalization ring storage groove of the vane that is sufficient to store one pressure equalization ring has the conventional 2 The width of the groove in the radial direction can be made narrower than the groove that accommodates each pressure-equalizing ring, and the side wall surface of the vane housing groove where there is no joint between the pressure-equalizing ring and the vane is the radial direction for connecting the vane of the conventional pressure-equaling ring. The stepped portion on which the protruding portion is placed becomes unnecessary and becomes a flat surface. Therefore, this surface is closer to the surface of the pressure equalizing ring than in the past, and the pressure equalizing ring housing groove is engraved in the overhanging portion at the tip of the vane. , The area of the part of the groove of the vane which is not connected to the pressure equalizing ring and faces the pressure equalizing ring Since wider than conventionally is larger capacitance of 此 parts. By increasing the capacitance in the above two parts, it is possible to secure almost the same capacitance as in the case where two pressure equalizing rings are conventionally used, and measures such as enlarging the outer diameter of the anode cylinder are taken. It is unnecessary. Furthermore, the circumferential width of the end surface connected to the vane of the vane connecting radial projection of the pressure equalizing ring is equal to or less than the circumferential wall thickness of the vane other than the protruding portion of the tip. Until it becomes equal to the wall thickness in the direction (since the output conductor was connected to one vane as described above, current flows through the pressure equalizing ring, but the width of the joint between the pressure equalizing ring and the vane is (It is clear that there is no problem even if the thickness is the same as the wall thickness.) Becomes

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1A is a top view of an anode portion according to an embodiment of the present invention, and FIG. 1B is a sectional view taken along the line AA 'shown in FIG. 2 (a) is a plan view of only the anode cylinder 1a according to the present invention, and FIG. 2 (b) is a pressure equalizing ring carved in the protruding portion 2b at the tip of the vane 2a of the anode cylinder 1a according to the present invention. The pressure equalizing ring 3a according to the present invention is housed in the storage groove 5a, and the vane connecting radial protrusion 23a of the pressure equalizing ring 3a is placed on the stepped portion on the inner side wall surface of the storage groove 5a.
It is an enlarged plan view showing the state where the end face of a was fitted and joined to the inner side wall face of the storage groove 5a. As shown, the pressure equalizing ring 3a
The width T ₁ of the circumferential end surface of the radial connecting portion 23a for connecting the vanes is smaller than the width T ₂ of the inner side wall surface of the pressure equalizing ring housing groove 5a formed in the overhanging portion 2b at the tip of the vane 2a,
The thickness of the pressure equalizing ring 3a is almost the same as the radial thickness.

As described above, since there is no degree of freedom in thermal deformation between the time of operation and the time of non-operation, the width in the circumferential direction of the brazed joint between the pressure equalizing ring and the vane is narrower than that of the conventional one. The length of the part of the pressure ring that is easily thermally deformed increases, and the thermal stress generated in the pressure equalization ring due to the temperature change of the magnetron is relaxed, and the fatigue damage accident rate of the pressure equalization ring due to repeated application of thermal stress decreases. .. Moreover, the vicinity of the joint between the pressure-equalizing ring and the vane is located in the thick overhanging portion at the tip of the vane, so that heat is radiated well, which helps to reduce the thermal stress of the pressure-equalizing ring. Further, since the length of the deformable portion of the pressure equalizing ring is longer than that of the conventional one, it becomes easy to forcibly deform the pressure equalizing ring during the manufacturing process to adjust the resonance frequency to a desired value, facilitating mass production. To do.

A protruding portion 2b is provided at the tip of the vane 2a, and the gap between the protruding portions of the adjacent vane tips is considerably narrower than the distance between the conventional adjacent vane tips. In the case of the magnetron of the present invention, the electric capacity is considerably larger than in the conventional case. Further, the facing area between the pressure equalizing ring and the vane not connected to the pressure equalizing ring is also larger than the conventional one because the pressure equalizing ring housing groove is provided at the protruding portion of the vane tip, and therefore the capacitance of this portion is large. Is also larger than before. For the above-mentioned two reasons, conventionally, two equalizing rings are provided on the axially upper and lower end surfaces of the vane, respectively, whereas in the present invention, only one equalizing ring is provided. The same resonance frequency as the conventional one can be obtained with the same outer diameter of the conventional anode cylinder.

The circumferential width T ₁ of the vane connecting radial projection 23a of the pressure equalizing ring 3a is determined by the width of the inner side wall surface of the pressure equalizing ring receiving groove 5a formed in the overhanging portion 2b at the tip of the vane 2a. Since it is narrower than T ₂ and is almost the same as the radial thickness of the pressure equalizing ring 3a, when the pressure equalizing ring is installed in the pressure equalizing ring housing groove of the anode cylinder, the pressure equalizing ring protrudes even if it is slightly displaced from a predetermined position. The entire end surface of the portion 23a is always in contact with the inner side wall surface of the pressure equalizing ring housing groove 5a of the vane, so that brazing is always performed reliably.

According to the present invention, when only one type of pressure equalizing ring is used, not only a great effect that the number of parts is reduced but also the joint portion between the pressure equalizing ring and the vane is reduced by half, so that as described above. Assembling becomes easier, defects at joints are reduced, and inspection man-hours are also reduced.

[0016]

As described above, according to the present invention, it is possible to obtain a magnetron having high mass productivity and high reliability.

[Brief description of drawings]

FIG. 1A is a top view of an anode part according to an embodiment of the present invention,
(B) is a sectional view along the line AA 'shown in (a).

FIG. 2 (a) is a plan view of only the anode cylinder according to the present invention, and FIG. 2 (b) is a view showing the inside of a pressure equalizing ring housing groove formed in an overhanging portion of the vane tip of the anode cylinder according to the present invention. The pressure equalizing ring according to the invention is housed, the radial connecting projection of the vane connecting ring of the pressure equalizing ring is placed on the stepped portion of the inner side wall surface of the storage groove, and the end surface of the protruding part is fitted and joined to the inner side wall surface of the storage groove. It is an enlarged plan view showing the state.

FIG. 3 is a sectional view taken along a plane including a tube axis of an example of a conventional magnetron generally used in a microwave oven or the like.

FIG. 4 is a top view of a conventional anode cylinder portion.

[Explanation of symbols]

1, 1a ... Anode cylinder, 2 ... Vane, 2a ... Vane according to the present invention, 3 ... Inner pressure-equalizing ring, 3a ... Equalizing ring according to the present invention, 4 ... Outer equalizing ring, 5 ... Equalizing-ring accommodating groove, 5
a ... equalizing ring accommodating groove according to the present invention, 6 ... output conductor, 7
Output conductor end portion, 8 ... Output portion, 9 ... Magnetic pole, 10 ... Permanent magnet, 11 ... Yoke, 12 ... Cathode, 13 ... Cooling fin, 14 ... Groove, 23a ... Vane connecting radial protrusion.

Claims (1)

[Claims] 1. In a magnetron in which a cavity resonator group is formed on the inner circumference of an anode cylinder by an anode cylinder and a plurality of vanes radially protruding from the inner wall of the anode cylinder, the tip of each vane is symmetrical to the tip side of both adjacent vanes. Protruding overhanging parts are formed on the upper and lower surfaces of the overhanging parts, and equalizing ring receiving grooves are vertically symmetrically engraved on the axially upper and lower end surfaces of the protruding parts. One equalizing ring having the same shape and size, which are evenly distributed in the circumferential direction, is housed one by one, and the end faces of the protruding portions of both equalizing rings are electrically connected to the side wall faces of the groove, respectively, and every other one. One half of the vanes of one set are connected to the same pressure equalizing ring in the groove of the upper end surface, and every other half of the vanes of the other set are connected to the same pressure equalizing ring. ..