JPH0510342Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Field of Industrial Application) The present invention relates to a variable inductor element used in, for example, televisions, tape recorders, and the like.

(Prior Art) FIGS. 4a and 4b show a high frequency transformer using a conventionally known variable inductor element. A tall holder d is set upright on the outer base of a drum core b placed on the upper surface of the base a, and a cap core c having a screwdriver groove g provided on the upper surface is screwed into the inside of the holder d. At the same time, a shield case e is attached to the outside of the holder, the top surface of which is provided with an operating hole f for operating the screw groove g of the cap core c.

The shield case e may have a shape in which the upper surface is completely open. The screwdriver groove g is formed in a rectangular shape as shown in FIG.

In the variable inductor element configured as shown in Fig. 4, the screwing position with the holder d is adjusted by rotating the cap core 2, and the inductance value is adjusted by the action with the inductor b housed inside. I try to do this. This adjustment is performed by inserting and locking the tip 8a of the driver 8 into the screw turning groove 6 formed in the cap core c, and rotating it in either direction.

(Problems to be Solved by the Invention) By the way, if we consider the ideal state of the cap core c made of ferrite as described above, it will be as shown in FIG. 5a. In this state, there appears to be no problem when inserting the tip 8a of the driver 8 into the screwdriver groove 6 in the direction of arrow B and rotating it.

However, in reality, when the cap core c is sintered, deformation as shown in FIG. 2b occurs.

That is, the screwdriver groove bottom 6a is thinner than other parts, and distortion is concentrated in this part during sintering.
As a result, a convex deformation occurs upward in the figure.

However, when trying to rotate the cap core c with the driver 8 in such a deformed state, the surface of the screw-driving groove bottom 6a, that is, the convex top 6b and the tip 8a of the driver 8 makes point contact with the contact surface 8b. Therefore, stress concentration occurs here, causing cracks, breakage, etc., and as a result, there is a problem that the characteristics of the variable inductor element are adversely affected. It is also conceivable to provide a notch in the portion where deformation occurs, but this would result in a reduction in the shielding effect.

Therefore, an object of the present invention is to provide a variable inductor element that eliminates the influence of sintering and does not cause problems even if the bottom of the screwdriver groove is deformed.

[Structure of the invention] (Means for solving the problems) The structure of the invention to solve the above problems is as follows:
A cap core that has a cylindrical shape with a bottom and is provided with a screw-driving groove on the circumferential side of the bottom and a screw portion formed on the circumferential side, and a screw that screws into the screw portion formed on the circumferential side of the cap core. A variable inductor element comprising a holder having a child part formed on an inner circumferential side surface, a base supporting the holder, and an inductor provided on the base, wherein a recess is formed in a part of the bottom of the screwdriver groove. It is characterized by what it did.

(Function) The function of the present invention having the above configuration is that a recess is formed in a part of the bottom of the screwdriver groove formed in the cap core, and even if the bottom of the recess is deformed due to sintering, Depending on the deformation of the recessed portion, it is prevented from coming into contact with the contact surface of the tip of the driver.

(Example) Fig. 1a is a sectional view of the cap core 2, and Fig. 1b is a view taken from the direction of arrow C shown in Fig. 1a.
Incidentally, since the other structure of the variable inductor element except for the cap core is almost the same as that shown in FIG. 4, a description of the structure will be omitted here.

As shown in Figures a and b, the screwdriver groove 12 of one embodiment formed in the cap core 2 is a part of the screwdriver groove bottom 12a, that is, the central portion in this embodiment, and has a long length. A recess 9 is formed over a predetermined range in the axial direction. Moreover, the formation position of this recessed part 9 is not limited to the central part, but may be formed at a position slightly biased to either side.

The width of the recess 9 is formed to be equal to the width H of the screwdriver groove 12 (see b in the same figure). By forming this recess 9, the thickness of the screwdriver groove bottom 12a is the smallest at the recess 9 portion.

To give specific dimensions near the recess 9, if the wall thickness 11 of the bottom of the recess 9 is, for example, 0.4 to 0.45 mm, the dimensions of the bottom surface 9a of the recess 9 and the screwdriver groove bottom surface 12a are It has been experimentally demonstrated that good results can be obtained even when the thickness is set to 0.05 to 0.1 mm. It should be noted that this specific dimension value is not limited to this value, but in short, it is sufficient to consider the deformation range due to sintering and set a dimension value that has a depth greater than this value.

The operation and effects of the present invention having the above configuration will be explained with reference to FIG. 2.

Insert the tip 8a of the driver into the screwdriver groove 12 of the cap core 2.

In this case, the bottom surface 12a of the screwdriver groove 12
and the contact surface 8b of the driver are in contact with each other.

However, since the aforementioned recess 9 is formed in the center of the screwdriver groove 12, even if the surface of the bottom 9a of the recess 9 is deformed upward in the figure due to sintering, The top portion 9b and the abutment surface 8b of the driver 8 are prevented from coming into contact by appropriately setting a gap 14 between the bottom surface 9a of the recess 9 of the deformed surface. It is preferable that the gap 14, the bottom wall thickness 11, etc. be set for each variable inductor element through experiments or the like.

As a result of the above, no cracks, damage, etc. will occur in the bottom portion of the screwdriver, and the characteristics of the variable inductor element will not be adversely affected.

It should be noted that the present invention is not limited to the illustrated embodiments, and can be modified in various ways within the scope of its gist.

For example, the recess formed in the screwdriver groove may be as shown in FIG. 3.

The recess 13 shown in the figure has a bottom back surface 13b.
is formed so as to protrude downward in the drawing.

When configured in this way, in addition to the above-mentioned effects, deformation due to sintering is less likely to occur, and
Even if such deformation occurs, the amount of deformation can be reduced, and the strength of that portion can also be increased.

Furthermore, in the above-described embodiments, the screwdriver groove has been described as having a so-called "-" shape, but this can also be applied to a "+" shape.

[Effects of the invention] As detailed above, according to the invention, the influence of sintering is eliminated, and even if the bottom of the screwdriver groove is deformed, there will be no cracks or damage caused by it. Inductor elements can be provided.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a recess formed at the bottom of the screwdriver groove, and FIG. 1a is a cross-sectional view in the longitudinal direction of the screwdriver groove, and FIG. Fig. 2 is an explanatory diagram of the action and effect of the recess formed at the bottom of the screwdriver groove shown in Figs. 1a and b, and Fig. 3 is the bottom of the screwdriver groove. 4a and 4b are a sectional view of a conventional variable inductor element and a plan view of a cap core, and FIGS. 5a and 5b are a sectional view of another example of a recess formed in a screwdriver by sintering. It is an explanatory view of deformation of the bottom of a groove. a...Base, b...Inductor, c, 2...
Cap core, d... holder, e... shield case, 8... screwdriver (driver), 9... recess, 12... screwdriver groove, 12a... screwdriver groove bottom.

Claims (1)

[Scope of utility model registration request] A cap core that has a cylindrical shape with a bottom and has a screw-driving groove on the outer surface of the bottom and a screw portion formed on the circumferential side, and a screw that screws into the screw portion formed on the circumferential side of the cap core. A variable inductor element comprising a holder having a child part formed on an inner circumferential side surface, a base supporting the holder, and an inductor provided on the base, wherein a recess is formed in a part of the bottom of the screwdriver groove. A variable inductor element characterized by: