JPH0666134B2 - Magnetron - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a magnetron incorporated in a microwave oven or the like.

(B) Prior Art FIG. 2 shows a conventional magnetron as disclosed in Japanese Utility Model Laid-Open No. 55-11796, (1) is a magnetron body having a cavity resonator, and (2a) and (2b) are the magnetrons. A pair of first and second permanent magnets that apply magnetic energy to the working space of the main body, (3)
Is a yoke that is magnetically coupled to the first and second permanent magnets (2a) and (2b) to form a magnetic circuit, and the yoke is a flat plate-shaped first yoke body (3a) in consideration of assembly workability and the like. And U-shaped second
It has a two-part structure composed of a yoke body (3b). (Four)
Extends from the magnetron body (1) and is the first of the above yoke (3)
An output portion that projects from the yoke body (3a) and radiates a microwave output, (5) an input portion that projects in the opposite direction to the output portion, (6)
Is a filter circuit of LC configuration connected to the input section, (7)
Is one surface on the outer peripheral surface of the second yoke body (3b) of the yoke (3)
It is a shield case that is placed in contact with (7 ') and accommodates the filter circuit (6).

Thus, in such a magnetron, the thicknesses t ₁ and t _{2 of the} yoke bodies (3a) and (3b) of the yoke (3) that form the magnetic circuit are
Is designed to have a minimum dimension t ₀ that does not cause magnetic saturation, for example. As a result, the first and second permanent magnets (2a) (2b)
The yoke (3) magnetically coupled with the first, specifically, the first
-For the second yoke body (3a) (3b), the magnetic flux concentration portion (3
No magnetic saturation occurs at a ') (3b'). In addition, other portions, for example, opposite side walls (3b ″) of the U-shaped second yoke body (3b)
In (3b ″), magnetic flux is dispersed and the magnetic flux density is low, so of course magnetic saturation does not occur.

However, in this case, the magnetic flux is dispersed and the magnetic flux density is low on the opposite side walls (3b ″) (3b ″) as described above, and therefore, the minimum magnetic field does not saturate on the opposite side walls (3b ″) (3b ″). dimensions has become remains above dimensions t ₀ despite a smaller than the dimension t _0, which only the opposite side (3
The thickness of b ″) (3b ″) is unnecessarily thick, which hinders weight reduction and cost reduction of the magnetron.

(C) Problem to be Solved by the Invention The present invention is intended to reduce the weight and cost of a magnetron.

(D) Means for Solving the Problems The present invention provides a magnetron body having a cavity resonator, a shield case made of a magnetic material, and containing a filter circuit connected to an input portion of the magnetron body, a first case, and a shield case. , A U-shaped second yoke body having opposite side walls,
A magnetron having a yoke forming a magnetic circuit with the shield case arranged on the outer periphery, and first and second permanent magnets provided in the yoke and magnetically coupled to the first and second yoke bodies, respectively. In the above, the one surface of the shield case is made to be a part of the magnetic circuit by facing the second permanent magnet with the bottom portion which is the magnetic flux concentration portion of the U-shaped second yoke body being sandwiched, and The thickness of the second yoke body is thinner than the thickness of the first yoke body.

(E) Action One surface of the shield case becomes a part of the magnetic circuit, and the thickness of the second yoke body is reduced accordingly.

(F) Embodiment FIG. 1 shows a magnetron according to an embodiment of the present invention. To explain only the differences from the conventional example, the shield case (7) is made of a magnetic material, and one surface (7 ') of which is the second yoke body. It faces the second permanent magnet (2b) with (3b) in between and is a part of the magnetic circuit. Further, the thickness t ₁ of the first yoke body (3a) is determined to be the minimum dimension t ₀ that does not cause magnetic saturation, and the second yoke body (3a)
The thickness t _{2 of} b) is made thinner than the thickness t ₁ of the first yoke body (3a), and the sum t with the thickness t ₃ of one surface (7 ′) of the shield case (7) is t.
It is determined that m is the minimum dimension t ₀ that does not cause magnetic saturation.

That is, although the thickness t ₂ of the second yoke body (3b) is thinner than the thickness t _{1 of} the first yoke body (3a) determined to be the minimum dimension t ₀ that does not cause magnetic saturation, Magnetic flux concentration part (3
The magnetic thickness of the bottom part which is b ') is the shield case (7)
It is compensated as the sum tm with the one surface (7 '), and magnetic saturation does not occur in the vicinity of the magnetic flux concentration portion (3b').

Since the thickness t ₂ of the second yoke (3b) is thin as described above, the weight and cost of the magnetron can be reduced accordingly.

In this case, the opposite side walls 3b ″) (3b ″) of the second yoke body (3b) remain thin and are not compensated like the magnetic flux concentrating portion (3b ′), but the opposite side walls (3b ″) (3b) In ″), since magnetic flux is dispersed, magnetic saturation does not occur and there is no problem.

(G) Effect of the Invention According to the present invention, since the shield case is effectively used as a part of the magnetic circuit, it is possible to make one yoke body thinner than the other yoke body in the yoke composed of two yoke bodies. Therefore, it is possible to remarkably reduce the weight and cost of the magnetron as the number of materials used decreases.

[Brief description of drawings]

FIG. 1 is a sectional view of a magnetron according to an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional magnetron. (1) ... magnetron body, (2a) (2b) ... first and second permanent magnets, (3) ... yoke, (3a) (3b) ... first and second yoke bodies, (3b ') ) …… Magnetic flux concentration part, (3b ″) (3b ″) …… Opposite side wall, (5) …… Human power part, (6) …… Filter circuit, (7) ……
Shield case.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References SHO 55-11796 (JP, U) ACT 55-2009 (JP, U) ACT 57-126153 (JP, U) ACT 50- 89253 (JP, U) Actual development Sho 49-120161 (JP, U) Registered utility model 362442 (JP, Z2)

Claims (1)

[Claims] 1. A magnetron body having a cavity resonator,
A shield case made of a magnetic material for accommodating a filter circuit connected to the input part of the magnetron body, and a U-shaped second yoke body having first and second opposing side walls and having a substantially uniform thickness. At the same time, a yoke forming a magnetic circuit with the shield case arranged on the outer periphery, and first and second permanent magnets provided in the yoke and magnetically coupled to the first and second yoke bodies, respectively. In the magnetron equipped with the
The bottom surface of the second yoke body having a letter-shaped shape, which is a magnetic flux concentration portion, is sandwiched between the second yoke body and the second permanent magnet so as to face the substantially entire surface of the second permanent magnet to form a part of the magnetic circuit. A magnetron having a thickness smaller than that of the first yoke body.