JP2002064023A - Choke coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a choke coil of which characteristic in a high-frequency band is improved and of which reliability against impact is so high that any crack hardly occurs in a drum core even if an impact is given to the drum core or the drum core is reduced in height. SOLUTION: An annular ring member 11 is made of liquid-crystal polymer- based insulation resin that is adhered to a drum core 4 with an adhesive agent 10 made of thermosetting type epoxy-based insulation resin, and arranged around the outer circumference of a winding axis 1 of the drum core 4. The inner circumferential surface 13 of the ring member 11 is arranged opposite to the outer circumferential surface 12 of an upper flange 2 and the outer circumferential surface 12 of a lower flange on the drum core 4. The linear expansion coefficient of the ring member 11 (1.3-5.6×10-5/ deg.C for liquid crystal polymer- based insulation resin) is set larger than that of the drum core 4 (9.5-9.7×10-6/ deg.C for Ni-Zn-based ferrite core).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a choke coil used for various electronic devices and the like.

[0002]

2. Description of the Related Art A conventional choke coil will be described below with reference to the drawings.

FIG. 8 is a perspective view of a conventional choke coil, and FIG. 9 is a DC-DC drive for driving a liquid crystal when the choke coil is used.
FIG. 10 is a DC circuit diagram, and FIG. 10 is a characteristic waveform diagram of frequency-Q value.

In FIG. 8, a conventional choke coil is
A drum core 31 having an upper end flange at one end of the winding shaft portion, and a lower end flange having a diameter substantially equal to the diameter of the upper end flange at the other end of the winding shaft portion;
The winding 32 wound around the winding part of the drum core 31 and the outer periphery of the winding part of the drum core 31 so as to prevent the winding 32 from being damaged due to external stress at the time of mounting / transportation. A ring-shaped ring member 33 made of a metal plate disposed above, a terminal plate 34 disposed on the lower surface of the lower end flange of the drum core 31, and the terminal plate 34 was implanted and electrically connected to the winding 32. A terminal 35 is provided.

As shown in FIG. 9, the choke coil 36 is connected to a chopper type DC-DC circuit for driving a liquid crystal, and its operating frequency is in a low frequency range of about 300 KHz. The characteristic waveform of the frequency-Q value at this time is as shown in FIG.

[0006]

In general, the use of choke coils in a high frequency band such as a DC-DC circuit of a liquid crystal driving circuit is increasing, and a choke coil is used in a higher frequency band (800K or more).
In addition to the demand for improved characteristic waveforms corresponding to use at about (Hz), miniaturization and height reduction are required to make the external dimensions extremely small and about several mm.

In the above-described conventional configuration, the ring member 33 made of a metal plate is attached to protect the winding 32 wound around the drum core 31 from disconnection or the like. Since the drum core 31 is made of a sintered magnetic material, it is brittle. When an impact is applied or when the height is reduced, the drum core 31 is cracked (an interface between the winding shaft and the upper end flange / lower end flange, etc.). This is problematic in that it tends to occur and impact reliability is reduced.

The present invention solves the above-mentioned problems. In addition to improving the characteristics in a high frequency band, even when an impact is applied to the drum core or the height of the drum core is reduced, the drum core is hardly cracked, and the impact is reduced. It is an object of the present invention to provide a choke coil with improved reliability.

[0009]

To achieve the above object, the present invention has the following arrangement.

The invention according to claim 1 of the present invention is characterized in that a ring-shaped ring member in which a ring member and the drum core are bonded with an adhesive is disposed on an outer periphery of a winding shaft portion of the drum core. The inner peripheral surface of the ring member is disposed so as to face the outer peripheral surface of the upper flange and the outer peripheral surface of the lower flange of the drum core. The material of the ring member is an insulating resin, and the coefficient of linear expansion of the ring member is Is larger than the linear expansion coefficient of the drum core.

According to the above configuration, since the ring member is disposed on the outer periphery of the winding shaft portion of the drum core, the winding wound around the drum core is damaged at the time of mounting / transporting by a parts feeder or the like, thereby causing disconnection or the like. Nothing. In particular, since the inner peripheral surface of the ring member is disposed so as to face the outer peripheral surface of the upper flange and the outer peripheral surface of the lower flange of the drum core, external force from the outer peripheral surface of the upper flange and the outer peripheral surface of the lower flange is directly applied. Irrespective of the drum core, the upper and lower flanges of the drum core can be protected even if the flange thickness is extremely thin, so that core cracking can be prevented.

In addition, since the material of the ring member is made of an insulating resin and the ring member is adhered to the drum core with an adhesive, the outer dimensions of the drum core and the ring member are reduced.
mm (especially the height dimension is 1 mm or less), making it extremely small and thin. Even if an impact is applied to the drum core, the impact is absorbed by the ring member via the adhesive and the Cracks are less likely to occur.

Further, since the material of the ring member is made of an insulating resin, the Q value in a high frequency band can be improved, and in particular, an insulating resin having a linear expansion coefficient larger than a linear expansion coefficient of the drum core is used. Since the material of the ring member is used, even when the drum core or the ring member becomes high temperature by using solder or using a thermosetting adhesive when electrically connecting the winding and the terminal, the drum core and the The difference in the expansion coefficients of the ring members is suppressed, and the drum core is less likely to crack.

As a result, the characteristics in the high frequency band are improved, and even when the drum core is subjected to an impact or the height is reduced, the drum core is hardly cracked, and the impact reliability can be improved.

The second aspect of the present invention is the first aspect.
In the invention described above, in particular, the ring member is made of a liquid crystal polymer-based insulating resin.

According to the above configuration, even when the ring member is heated to a high temperature state by using solder at the time of electrical connection between the winding and the terminal, or by using a thermosetting adhesive, the material of the ring member is changed. Since it is a liquid crystal polymer-based insulating resin, it has heat resistance and does not deteriorate electrical characteristics such as a Q value in a high frequency band.

The third aspect of the present invention is the first aspect of the present invention.
In the described invention, in particular, the inner peripheral surface of the ring member is brought into contact with the outer peripheral surface of the upper flange and the outer peripheral surface of the lower flange of the drum core.

According to the above configuration, the position of the ring member can be accurately regulated with respect to the drum core.

The fourth aspect of the present invention is the first aspect.
In the invention described above, the ring member is particularly provided with a ring notch portion serving as a discontinuous portion.

According to the above configuration, when the ring member is arranged, the ring member can be easily fitted to the drum core while the ring cutout of the ring member is widened to the left and right, and the position can be accurately regulated.

The fifth aspect of the present invention is the first aspect of the present invention.
In the invention described in the above, in particular, the inner peripheral surface of the ring member is brought into contact with the outer peripheral surface of the upper end flange and the outer peripheral surface of the lower end flange of the drum core, and the ring member is provided with a ring notch serving as a discontinuous portion, The shape of the portion is a T-shape, and a convex portion is formed at both opposite ends of the ring member so that the convex portion comes into contact with the outer peripheral surface of the upper flange or the outer peripheral surface of the lower flange of the drum core. It is a configuration that is arranged.

According to the above configuration, when the ring member is arranged, the ring member can be easily fitted to the drum core while widening the ring cutout of the ring member to the left and right, and the position can be accurately regulated. In particular, if the facing convex portions of the ring member are connected in advance and cut when fitting, the cutout portion of the ring member may be inadvertently expanded until the ring is fitted. It is possible to prevent the fitting from becoming impossible by increasing the inner diameter of the member.

The invention according to claim 6 of the present invention is characterized by claim 1
In the described invention, in particular, the lower surface of the ring member is arranged above the lower surface of the mounting portion of the terminal.

According to the above configuration, when mounted on the mounting board, the lower surface of the ring member comes into contact with the mounting board surface, and it is possible to prevent a decrease in the connection reliability of the terminal to the mounting board surface.

The invention according to claim 7 of the present invention is the invention according to claim 1.
In the described invention, in particular, while making the ring width dimension of the ring member larger than the core length dimension of the drum core,
In this configuration, the drum core projects vertically from the upper and lower surfaces.

With the above configuration, it is possible to more accurately protect the drum core against contact with the upper end flange and the lower end flange.

[0027] The invention according to claim 8 of the present invention is directed to claim 1.
In the described invention, in particular, the ring member is provided with a ring notch serving as a discontinuous portion, the inner diameter of the ring member is smaller than the upper end flange diameter and the lower end flange diameter of the drum core, and the outer peripheral surface of the upper end flange of the drum core and It is configured to be in contact with the outer peripheral surface of the lower end flange.

When arranging the ring member, the ring member can be easily fitted to the drum core while widening the ring notch of the ring member to the left and right, and the ring member is formed by the outer peripheral surface of the upper flange of the drum core and the lower flange. Since the contact is made with the outer peripheral surface, the position can be regulated accurately.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiments) The inventions described in all claims of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a choke coil according to an embodiment of the present invention, FIG. 2 is a top view of the choke coil, FIG. 3 is a perspective view of the choke coil, FIG. FIG. 5 is a bottom view of the choke coil,
FIG. 6 shows a DC for driving a liquid crystal in a state where the choke coil is used.
FIG. 7 is a characteristic waveform diagram of a frequency-Q value of the choke coil.

1 to 6, a choke coil according to an embodiment of the present invention is used in a DC-DC circuit for driving a liquid crystal shown in FIG.
Ni-Zn having a lower end flange 3 at the other end of the winding portion 1
Drum core 4 composed of a ferrite core (core length: 0.7 to 1.0 mm, core diameter: 4.0 to 5.0 mm, reel diameter: 0.1 to 0.3 mm, flange thickness at upper end flange) Dimensions and flange thickness of the lower end flange are set in the range of 0.1 to 0.3 mm), the winding 5 wound around the winding shaft portion 1 of the drum core 4 and the lower surface of the lower end flange 3. A terminal plate 6 and a terminal 7 partially embedded in the terminal plate 6 and electrically connected to the winding 5 are provided. At this time, a hole 8 is provided in the center of the drum core 4, a projection 9 is provided in the center of the terminal plate 6, and the projection 9 of the terminal plate 6 is provided in the hole 8 of the drum core 4.
Is inserted.

An adhesive 10 made of a thermosetting epoxy-based insulating resin is provided on the outer periphery of the winding shaft 1 of the drum core 4.
In addition, a ring-shaped ring member 11 made of a liquid crystal polymer-based insulating resin adhered to the drum core 4 is arranged, and the inner peripheral surface of the ring member 11 is formed on the outer peripheral surface 12 of the upper flange 2 and the outer peripheral surface 12 of the lower flange 3 of the drum core 4. The surfaces 13 are arranged so as to face each other, and the coefficient of linear expansion of the ring member 11 (in the case of a liquid crystal polymer-based insulating resin, (1.3 to 5.6 ×
10 ⁻⁵ / ° C.)) to the coefficient of linear expansion (Ni-Z) of the drum core 4.
In the case of an n-type ferrite core, (9.5 to 9.7 × 10 ⁻⁶⁾
/ ° C)).

At this time, the coefficient of linear expansion of the adhesive 10 is set to 2.
It is set to 3 to 3.0 × 10 ⁻⁵ / ° C. (conventionally, about 5.0 × 10 ⁻⁵ / ° C.).

Further, the ring member 11 is provided with a T-shaped ring notch portion 14 serving as a discontinuous portion.
A convex portion 15 is formed at both opposite ends of the drum core 4 so that the inner peripheral surface 13 and the convex portion 15 of the ring member 11 not only oppose the outer peripheral surface 12 of the upper flange 2 of the drum core 4 but also come into contact therewith. I have.

At this time, the inner diameter of the ring member 11 is made slightly smaller than the upper end flange diameter and the lower end flange diameter of the drum core 4 so that the ring member 11 itself bends while the ring cutout portion 14 is being widened. The ring member 11 is fitted to the drum core 4 by the elastic force of

The gap 10 formed by the ring member 11 and the drum core 4 is filled with the adhesive 10, and the contact surface between the ring member 11 and the drum core 4 is also filled with the adhesive by capillary action or the like. 10 have penetrated.

The terminal 7 has a mounting portion 17 for mounting.
And a connecting portion 18 connected to the mounting portion 17 and a connecting portion 1
8 and a winding barb 19 for electrical connection with the winding 5. The connecting unit 18 is embedded in the terminal plate 6, and the mounting unit 17 and the winding barb 19 are connected.
Are projected from the terminal plate 6 in directions different from each other (for example, at right angles).

At this time, a core notch 20 is provided in the lower end flange 3 of the drum core 4, a terminal plate notch 21 is provided in the terminal plate 6 opposed to the core notch 20, and the winding portion 19 of the terminal 7 is formed. The winding 5 and the terminal 19 of the terminal 7 are electrically connected within the terminal plate notch 21 so as to project from the terminal plate notch 21.

Further, the lower surface of the ring member 11 is disposed above the lower surface of the mounting portion 17 of the terminal 7,
Is larger than the core length dimension (W2) of the drum core 4 and is projected vertically from the upper and lower surfaces of the drum core 4.

As shown in FIG. 6, the choke coil 22 is connected to a DC-DC circuit for driving a liquid crystal, and has an operating frequency in a high frequency range of about 800 KHz. Note that V
Is a power supply, T is a control element, D is a diode, C is a capacitor, and K is a load. The characteristic waveform of the frequency-Q value at this time is as shown in FIG.

The operation of the choke coil having the above configuration will be described below.

With the above configuration, the winding shaft 1 of the drum core 4
Since the ring member 11 is arranged on the outer periphery of the drum core 4, the winding 5 wound around the drum core 4 is not damaged due to external stress or the like during mounting / transportation. In particular, since the inner peripheral surface 13 of the ring member 11 is disposed so as to face the outer peripheral surface 12 of the upper flange 2 and the outer peripheral surface 12 of the lower flange 3 of the drum core 4, the outer peripheral surface 12 and the lower flange of the upper flange 2 are arranged. External force from the direction of the outer peripheral surface 12 of the drum core 3 is not directly applied to the drum core 4, and the upper and lower flanges 2 and 3 of the drum core 4 can be protected even if the flange thickness is extremely thin, and core cracking can be prevented.

Since the material of the ring member 11 is made of insulating resin and the ring member 11 is adhered to the drum core 4 with the adhesive 10, the outer dimensions of the drum core 4 and the ring member 11 are about several mm (especially high height). (The dimension is 1 mm or less), so that the drum core 4 can be made extremely small and thin. Even if an impact is applied to the drum core 4, the impact is absorbed by the ring member 11 via the adhesive 10 and the drum core 4
Cracks are less likely to occur.

Further, since the material of the ring member 11 is made of an insulating resin, the Q value in a high frequency band can be improved. Ring member 1 for resin
Assuming that the drum core 4 and the ring member 11 are in a high temperature state by using solder or using a thermosetting adhesive 10 when electrically connecting the winding 5 and the terminal 7 because the material 1 is used. Also, the difference in the expansion coefficient between the drum core 4 and the ring member 11 is suppressed, and the drum core 4 is less likely to crack.
At this time, as shown in FIG. 7, by using an insulating resin having a linear expansion coefficient larger than the linear expansion coefficient of the drum core 4 as the material of the ring member 11, the characteristic waveform of the frequency-Q value becomes equal to that of the conventional (C). (A) in the high frequency band as compared with (A), and the characteristics of the frequency-Q value can be improved.

As a result, the characteristics in the high frequency band are improved, and even if the drum core 4 is subjected to an impact or its height is reduced, the drum core 4 is hardly cracked.
Impact reliability can be improved.

In particular, the material of the ring member 11 is made of a liquid crystal polymer-based insulating resin, and the material of the drum core 4 is made of N.
Since an i-Zn ferrite core is used and the material of the adhesive 10 is a thermosetting epoxy-based insulating resin, the adhesive 1
When the epoxy-based insulating resin is cured by applying heat to 0, even if the ring member 11 is brought to a high temperature state, the material of the ring member 11 is a liquid crystal polymer-based insulating resin, so that it has heat resistance and has a high frequency band. Since the electrical characteristics such as the Q value are not deteriorated and the material of the drum core 4 is a Ni—Zn-based ferrite core, the ring member 11 and the drum core 4 are firmly adhered to each other due to a difference in expansion coefficient due to heat. Cracks of the drum core 4 can be accurately prevented. At this time, as shown in FIG. 7, the material of the ring member 11 is a liquid crystal polymer-based insulating resin, the material of the drum core 4 is a Ni-Zn-based ferrite core, and the material of the adhesive 10 is a thermosetting epoxy-based material. By using the insulating resin, the characteristic waveform of the frequency-Q value becomes (B) in a higher frequency band as compared with the conventional (C), and the characteristic of the frequency-Q value can be improved.

Since the gap 16 formed by the ring member 11 and the drum core 4 is filled with the adhesive 10, the impact applied to the drum core 4 is concentrated on a specific portion of the adhesive 10, and Since the impact is transmitted to the ring member 11 while being substantially evenly dispersed instead of being transmitted to the member 11, even if a particularly strong impact or the like is received, cracks do not occur in the vicinity of the bonding point between the drum core 4 and the adhesive 10. At this time, since the gap 10 is not present and the air layer is almost eliminated by filling the adhesive 10, the winding 5 is prevented from being corroded by moisture and the like contained in the air, and short circuit is prevented. it can.

Further, the winding 5 is a winding connecting part 1 of the terminal 7.
9, the winding 5 is not tied to the mounting portion 17 of the terminal 7, and when the mounting portion 17 is connected to the mounting board, the winding 5 is disconnected or the winding 5 is mounted. The connection reliability can be prevented from deteriorating without making the connection difficult, and at the same time, the terminal strip notch 21 can be used to prevent the winding portion 19 of the terminal 7 from being wound.
Projecting from the terminal plate 6, the protrusion dimension of the winding flared portion 19 to the outside of the ring member 11 can be suppressed by the diameter of the terminal plate cutout portion 21. It is possible to reduce the size while electrically connecting the wire 5 to the winding portion 19.

Since the hole 8 is provided at the center of the drum core 4, the protrusion 9 is provided at the center of the terminal plate 6, and the protrusion 9 of the terminal plate 6 is inserted into the hole 8 of the drum core 4. The position of the terminal plate 6 with respect to the drum core 4 can be accurately regulated.

Since the ring member 11 is provided with the ring notch 14 which is a discontinuous portion, when the ring member 11 is arranged, the ring member 11 is bent while expanding the ring notch 14 of the ring member 11 right and left. In addition, the ring member 11 can be easily fitted to the drum core 4 and the position can be accurately regulated.

In particular, the shape of the ring notch 14 is T-shaped, and the protrusions 15 are formed at both opposite ends of the ring member 11. The opposed protrusions 15 of the ring member 11 are connected in advance. If it is set so as to be cut when fitting, the ring notch 14 of the ring member 11 is inadvertently expanded until the fitting, so that the inner diameter of the ring member 11 is increased. It can be prevented from being disabled.

At this time, the inner diameter of the ring member 11 is made smaller than the upper and lower flange diameters of the drum core 4 so as to contact the outer peripheral surface 12 of the upper flange 2 and the outer peripheral surface 12 of the lower flange 3 of the drum core 4. Since the ring member 11 is in contact with the outer peripheral surface 12 of the upper end flange 2 and the outer peripheral surface 12 of the lower end flange 3 of the drum core 4, the position of the ring member 11 is precisely regulated, and the winding wound around the winding shaft portion 1 is performed. 5 can be protected.

Further, the lower surface of the ring member 11 is disposed above the lower surface of the mounting portion 17 of the terminal 7,
Is larger than the core length dimension (W2) of the drum core 4 and protrudes vertically from the upper and lower surfaces of the drum core 4, so that when mounted on a mounting substrate or the like, the mounting substrate In addition to preventing the lower surface of the ring member 11 from contacting the surface and lowering the connection reliability of the terminal 7 to the mounting substrate surface, the contact between the upper end flange 2 and the lower end flange 3 of the drum core 4 is more accurate. Protection.

As described above, according to the embodiment of the present invention, the Q-value characteristics in the high frequency band are improved, and the external dimensions of the drum core 4 and the ring member 11 are several mm when an impact is applied to the drum core 4. Degree (especially height dimension is 1
mm or less), the drum core 4 is less likely to crack and the impact reliability can be improved.

Even if the temperature of the drum core 4 or the ring member 11 becomes high, the linear expansion coefficient of the ring member 11 is larger than the linear expansion coefficient of the drum core 4, so that cracking of the drum core can be accurately suppressed.

In particular, the material of the ring member 11 is a liquid crystal polymer based insulating resin, and the material of the drum core 4 is N
Since the i-Zn-based ferrite core is used and the material of the adhesive 10 is a thermosetting epoxy-based insulating resin, the above effects can be further obtained.

In the embodiment of the present invention, a thermosetting insulating resin is used as the adhesive 10. However, other materials such as an elastic adhesive may be used. It can also absorb itself, further improving impact reliability.

In the embodiment of the present invention, a Ni--Zn ferrite core is used as the material of the drum core 4, but other materials such as a Mg--Zn ferrite core may be used.

[0059]

As described above, according to the present invention, since the ring member is arranged on the outer periphery of the winding shaft portion of the drum core,
There is no possibility that the winding wound around the drum core is damaged due to external stress during mounting / transportation and disconnection or the like occurs.

Since the ring member is made of insulating resin and the ring member is bonded to the drum core with an adhesive, the outer dimensions of the drum core and the ring member are mm.
(Especially the height dimension is 1 mm or less), so that the drum core can be made very small and thin. Even if a shock is applied to the drum core, the shock is absorbed by the ring member via the adhesive, and the drum core is broken. Is unlikely to occur.

Further, since the material of the ring member is made of an insulating resin, the Q value in a high frequency band can be improved. In particular, the insulating resin having a linear expansion coefficient larger than that of the drum core can be used. Since the material of the ring member is used, even if the drum core or the ring member becomes high temperature by using solder at the time of electrical connection between the winding and the terminal or using a thermosetting adhesive, the drum core is Since the linear expansion coefficient of the ring member is larger than the linear expansion coefficient, the drum core is less likely to crack.

As a result, it is possible to provide a choke coil which has improved characteristics in a high frequency band, and is less likely to crack in the drum core even when an impact is applied to the drum core or when the height is reduced, thereby improving the impact reliability. can do.

[Brief description of the drawings]

FIG. 1 is a sectional view of a choke coil according to an embodiment of the present invention.

FIG. 2 is a top view of the choke coil.

FIG. 3 is a perspective view of the choke coil.

FIG. 4 is a front view of the choke coil.

FIG. 5 is a bottom view of the choke coil.

FIG. 6 shows a liquid crystal driving D in a state where the choke coil is used.
C-DC circuit diagram

FIG. 7 is a characteristic waveform diagram of frequency-Q value of the choke coil.

FIG. 8 is a perspective view of a conventional choke coil.

FIG. 9 shows a liquid crystal driving D in a state where the choke coil is used.
C-DC circuit diagram

FIG. 10 is a characteristic waveform diagram of frequency-Q value.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Winding shaft part 2 Upper flange 3 Lower flange 4 Drum core 5 Winding 6 Terminal plate 7 Terminal 8 Hole 9 Protrusion 10 Adhesive 11 Ring member 12 Outer peripheral surface 13 Inner peripheral surface 14 Ring notch 15 Protrusion 16 Void 17 Mounting Part 18 Connecting part 19 Winding part 20 Core notch 21 Terminal plate notch 22 Choke coil

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H01F 27/02 H01F 15/02 D 27/29 R 17/04 15/10 D

Claims (8)

[Claims] A drum core having an upper end flange at one end of a winding shaft portion and a lower end flange at the other end of the winding shaft portion; a winding wound around the winding shaft portion of the drum core; A terminal plate mounted on the lower surface of the flange, and a terminal partially embedded in the terminal plate and electrically connected to the winding; and a ring member provided on an outer periphery of the winding shaft portion of the drum core. And a ring-shaped ring member in which the drum core and the drum core are bonded with an adhesive, and the inner peripheral surface of the ring member is arranged so as to face the outer peripheral surface of the upper flange and the outer peripheral surface of the lower flange of the drum core. A choke coil wherein the material of the ring member is an insulating resin and the coefficient of linear expansion of the ring member is larger than the coefficient of linear expansion of the drum core. 2. The choke coil according to claim 1, wherein the material of the ring member is a liquid crystal polymer-based insulating resin. 3. An inner peripheral surface of a ring member is brought into contact with an outer peripheral surface of an upper end flange of the drum core and an outer peripheral surface of a lower end flange of the drum core.
The choke coil described. 4. The choke coil according to claim 1, wherein the ring member is provided with a ring notch serving as a discontinuous portion. 5. An outer peripheral surface of an upper end flange and an outer peripheral surface of a lower end flange of a drum core are brought into contact with an inner peripheral surface of a ring member, and a ring notch portion serving as a discontinuous portion is provided on the ring member. The shape is a T-shape, and a convex portion is formed on both opposite ends of the ring member,
2. The drum core according to claim 1, wherein the protrusion is arranged so as to contact an outer peripheral surface of the upper flange or an outer peripheral surface of the lower flange of the drum core.
The choke coil described. 6. The choke coil according to claim 1, wherein the lower surface of the ring member is disposed above the lower surface of the terminal mounting portion. 7. The choke coil according to claim 1, wherein the ring member has a ring width dimension larger than a core length dimension of the drum core, and protrudes vertically from upper and lower surfaces of the drum core. 8. A ring member having a ring notch serving as a discontinuous portion and an inner diameter of the ring member smaller than an upper end flange diameter and a lower end flange diameter of the drum core, and an outer peripheral surface and a lower end flange of an upper end flange of the drum core. 2. The choke coil according to claim 1, wherein the choke coil is arranged so as to contact an outer peripheral surface of the choke coil.