JP2546356Y2 - Small inductor - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small inductor used in various electronic circuit devices, and more particularly to a small wound inductor in which a drum core wound with a coil is housed in a cylindrical core.

[0002]

2. Description of the Related Art As is well known, in recent years, the miniaturization of electronic circuit devices has become a major technical problem, and technical development has been actively conducted from the viewpoint of miniaturization of various electronic components and improvement of mounting density. . An inductor which is one of electronic circuit components is no exception, and a chip inductor having a non-winding structure is known as an ultra-small inductor. This is a structure in which a large number of insulating layers and conductive metal layers formed on a magnetic material such as ferrite in a planar shape are superposed, and a number of conductive metal layers are connected by through holes or lead wires to form a desired inductor. . The chip inductor having this structure requires a large number of manufacturing steps and is complicated, so that it is expensive, has low inductance, and has low withstand voltage and current.

[0003] An inductor having a winding structure in which coil winding is applied to a core of an appropriate form can provide a large inductance and can also increase withstand voltage and withstand current. However, it is difficult to make it ultra-small as in a non-wound structure chip inductor. As a relatively small-sized inductor having a winding structure, there is known an inductor having a structure in which a coil is wound around a drum core having flanges integrally at both ends, and the drum core is housed in a cylindrical core.

[0004]

A conventional inductor having a drum core wound with a coil and a cylindrical core combined with the outer periphery of the core has a structure in which components are mounted on a substrate having terminal pins. . In other words, terminal pins for external connection are planted on a board made of a printed wiring board or a plastic board, and a drum core and a cylindrical core wound with a coil are concentrically arranged on the board, and an adhesive is formed. It is fixed with. In this structure, since there is a substrate on which a core component is mounted, the height (thickness) of the inductor cannot be reduced so much, and it is difficult to realize a thin inductor particularly suitable for planar mounting. In the case of a type of inductor in which the drum core and the cylindrical core are not in contact with each other and a certain gap is provided between the cores, the drum core and the cylindrical core can be accurately positioned and fixed on the substrate. However, there is a problem that the gap between the two cores is not constant, and the variation in characteristics between products tends to be large.

The present invention has been made in view of the above-mentioned conventional problems, and in a type of inductor composed of a drum core wound with a coil and a cylindrical core, it is possible to make the inductor thin and suitable for planar mounting. It is another object of the present invention to provide a small-sized inductor in which a drum-type core and a cylindrical-type core can be easily combined and integrated easily.

[0006]

According to the present invention, there is provided a small-sized inductor having a drum core having flanges at both ends, a coil wound on the drum core, and an inner diameter larger than an outer diameter of the drum core. A cylindrical notch, a ring-shaped notch formed at an outer peripheral edge of the flange at one end of the drum-shaped core, and a ring-shaped notch formed at an inner peripheral edge of one end of the cylindrical core. In a state where the drum core is coaxially arranged in the cylindrical core, the outer periphery and the inner periphery are fitted into the ring-shaped notch of the cylindrical core and the ring-shaped notch of the drum core. And a spacer ring which is fixed to and integrated with the whole.

[0007]

The inner peripheral portion of the spacer ring fits into the ring-shaped notch of the drum core. The outer peripheral portion of the spacer ring is fitted into the ring-shaped notch of the cylindrical core. By fitting these three parts, the axial and radial positioning of the drum core and the cylindrical core is made simple and accurate, and the gap between the two cores becomes extremely uniform. In addition, since the spacer ring fits into the ring-shaped cutouts of the cores, the height (dimension in the axial direction) of the inductor does not increase due to the thickness of the spacer ring.

[0008]

1 and 2 show the structure of a first embodiment of the present invention. The drum type core 1 is made of ferrite and has flanges 1a and 1b at both ends, and a coil 2 is provided between the flanges.
Is wound. A ring-shaped notch 1c is formed on the outer peripheral edge of the upper surface of one of the flanges 1a.

The cylindrical core 3 is also made of ferrite, and its inner diameter is larger than the outer diameter of the flange of the drum type core 1. When both cores 1 and 3 are combined as shown in FIG. It has dimensions. The drum core 1 and the cylindrical core 3 have the same height, and a ring-shaped notch 3a is formed at the inner peripheral edge of the upper end surface of the cylindrical core 3.

The spacer ring 4 is made of plastic and is formed in a flat ring shape. The inner diameter of the spacer ring 4 is a size that fits snugly into the ring-shaped notch 1c of the drum core 1, and the outer diameter is a cylindrical core. 3 are fitted to the ring-shaped notch 3a. The thickness of the spacer ring 4 is equal to the depth of the ring-shaped cutouts 1c and 3a.

A drum-type core 1 wound with a coil 2 is housed in a cylindrical core 3, and spacer rings 4 are combined with both cores as shown in FIG. The inner peripheral portion of the spacer ring 4 is fitted into the ring-shaped notch 1c of the drum core 1, and the outer peripheral portion of the spacer ring 4 is fitted into the ring-shaped notch 3a of the cylindrical core 3. In this state, the spacer ring 4 and the cores 1 and 3 are fixed with an adhesive. In this way, the drum core 1 and the cylindrical core 3 are accurately positioned both in the axial direction and the radial direction.
3 and the spacer ring 4 are integrated.

In the embodiment shown in FIG. 1, a lead frame (terminal fitting) 5 is attached from the lower end to the outer peripheral portion of the cylindrical core 3 without the spacer ring 4 with an adhesive or the like, and the coil 2
Are connected to the lead frame 5. This inductor is mounted on the printed circuit board of the electronic circuit device,
The lead frame 5 is soldered to the wiring pattern of the board. At this time, since the lead frame 3 is attached from the lower end to the outer peripheral portion of the cylindrical core 3, it can be easily soldered in the same manner as a general planar mounting component.

Next, another embodiment of the present invention will be described. As shown in FIGS. 3 and 4, a relatively long strip-shaped lead frame 5 may be used and attached to the cylindrical core 3 so as to be wound from the lower end portion to the outer peripheral portion and the upper end portion. Also, a projection 5a is cut and raised in the middle of the lead frame 5, and the thin lead wire 2a of the coil 2 is
a. Also, as shown in FIG. 34, a concave portion 3b is formed at the lower end of the cylindrical core 3, and
The lead frame 5 is attached there. Then, since the lead frame 5 and the lead wire 2a do not protrude from the lower end surface of the core 3, the stability is improved when the lead frame 5 or the lead wire 2a is attached to a printed wiring or the like.

In the embodiment shown in FIG. 5, a terminal electrode layer 6 is printed (metallized) at a predetermined position from the lower end to the outer periphery of the cylindrical core 3, and the lead wire 2
a is connected. When the lead wire 2a of the coil 2 is thick and rigid to some extent, as shown in FIG. 6, the coil lead wire 2a is wired so as to pass through the concave portion 3b at the lower end of the cylindrical core 3 and drawn out to the outer periphery. It may be sufficient to bend only the lead wire 2a along the outer peripheral surface of the core.

[0015]

As described in detail above, according to the present invention, by combining a drum type core and a cylindrical type core using a very simple spacer ring, both cores are axially and radially oriented. Both directions are accurately positioned and integrated. Therefore, high-quality inductors having a uniform gap size between the two cores can be mass-produced inexpensively by a very simple assembly process. In addition, since the spacer ring is mounted so as to be embedded in the ring-shaped notch formed in the drum core and the cylindrical core, the spacer ring does not increase the height dimension of the inductor, but increases the height of both cores. The dimensions almost match the height dimensions of the completed inductor. That is, it is possible to realize a thin and small inductor suitable for planar mounting with a very simple structure.

[Brief description of the drawings]

FIG. 1 is a sectional view of a small inductor according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view of the inductor.

FIG. 3 is a sectional view of a main part of an inductor according to a second embodiment of the present invention.

FIG. 4 is a side view of a main part of the second embodiment.

FIG. 5 is a side view of a main part of a third embodiment of the present invention.

FIG. 6 is a side view of a main part of a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Drum type core 1a, 1b Flange 2 Ring-shaped notch 2a Lead wire 3 Cylindrical core 3a Ring-shaped notch 3b Depression 4 Spacer ring 5 Lead frame 5a Projection 6 Terminal electrode layer

Claims (5)

(57) [Scope of request for utility model registration] 1. A drum core having flanges integrally at both ends, a coil wound around the drum core, a cylindrical core having an inner diameter larger than an outer diameter of the drum core, and one end of the drum core. A ring-shaped notch formed on the outer peripheral edge of the flange of the portion, a ring-shaped notch formed on the inner peripheral edge of one end of the cylindrical core, and the drum-shaped core in the cylindrical core. A spacer ring that is fitted coaxially with the outer and inner peripheries of the ring-shaped notch of the cylindrical core and the ring-shaped notch of the drum core in a state where they are coaxially arranged and integrated with each other; Small inductor with. 2. A terminal portion extending from the other end portion of the cylindrical core to the outer peripheral portion by drawing out a lead wire of the coil from a gap between the drum core and the cylindrical core on the other end side where the spacer ring is not provided. The small inductor according to claim 1, further comprising: 3. The small-sized inductor according to claim 2, wherein a wiring recess is formed at the other end of the cylindrical core from which a lead wire of the coil is drawn out. 4. The small inductor according to claim 2, wherein said terminal portion has a terminal fitting joined to said cylindrical core. 5. The small inductor according to claim 2, wherein the terminal portion has a terminal electrode layer printed on the surface of the cylindrical core.