JP2004273510A

JP2004273510A - Line filter

Info

Publication number: JP2004273510A
Application number: JP2003058282A
Authority: JP
Inventors: Noboru Mizutani; 昇水谷; Toshihiro Narita; 敏洋成田
Original assignee: Tokyo Parts Ind Co Ltd
Current assignee: Tokyo Parts Ind Co Ltd
Priority date: 2003-03-05
Filing date: 2003-03-05
Publication date: 2004-09-30
Anticipated expiration: 2023-03-05
Also published as: CN1527330A; JP3886048B2; CN100541682C; TW200503004A; TWI288939B

Abstract

<P>PROBLEM TO BE SOLVED: To provide a line filter which is, in spite of having a common mode choke coil structure, provided with characteristics capable of limiting a leakage flux to the minimum, very stable in magnetic efficiency, and capable of restraining normal mode noises. <P>SOLUTION: The line filter is equipped with a square-shape closed magnetic circuit core 10, bobbins 30 and 31 where coils 20 and 21 are wound are fixed to a magnetic leg 11 as one side of the magnetic circuit core 10, and furthermore, the other magnetic leg 12 opposed to the magnetic leg 11 is arranged on the peripheral side of the coils 20 and 21. A U-shaped center core 40 is inserted between the bobbins 30 and 31 so as to separate them from each other, and furthermore a U-shaped core cover 50 is fixed so as to cover the other magnetic leg 12 and side magnetic legs 13 and 14 other than the magnetic leg 11 of the closed magnetic circuit core 10. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、各種電子機器の電気回路から発生するコモンモードノイズおよびノーマルモードノイズを除去するラインフィルタに関するものである。
【０００２】
【従来の技術】
従来から、基本的にはコモンモードチョークコイルの構造であるがノーマルモードノイズも抑制するチョークコイルが知られている。
このような構造としては、外周に絶縁物で隔てられた２個の巻線が互いに逆位相となるように巻かれた１個のコイル用ボビンを用いて、２個のＵ字形磁芯が向かい合わせてこのボビンの内外に組み付けられ略閉磁路を形成してなるチョークコイルであって、前記略閉磁路磁芯の一辺上の２個の巻線の間、すなわち、前記Ｕ字形磁芯の間にＨ形で板状のバイパス磁芯が接続されて、短絡磁路が形成されたコモンモードノイズとノーマルモードを抑制する複合チョークコイルが知られている（例えば、特許文献１参照）。
【０００３】
また、外周に絶縁物で隔てられた２個の巻線が互いに逆位相となるように巻かれた１個のコイル用ボビンの貫通孔を、閉磁路磁芯の一磁脚部に挿入し組み付け磁路を形成してなるチョークコイルであって、前記ボビンの２個の巻線の間にＵ字形のセンター磁芯が挿入されており、そのセンター磁芯の底部は前記閉磁路磁芯の一磁脚部に、また、そのセンター磁芯の開口部の先端縁部は前記閉磁路磁芯の他磁脚部に空隙を持って対向するように磁路が形成されたコモンモードノイズとノーマルモードを抑制する複合チョークコイルが知られている（例えば、特許文献２参照）。
【０００４】
【特許文献１】
特開平９−１３９３１７号公報
【特許文献２】
特開２００１−１１０６５４号公報
【０００５】
【発明が解決しようとする課題】
しかしながら、前述した従来技術のいずれにおいても後述するような問題点を抱えている。
すなわち、閉磁路を形成する磁芯が分割タイプで有るため、合わせ面に空隙が生じ、その空隙のばらつきにより漏洩磁束がばらつき、結果としてチョークコイル自体の特性のばらつきが大きくなる（特許文献１）、また、センター磁芯の開口部の先端縁部は前記閉磁路磁芯の一辺を構成する他磁脚部に空隙を持って対向するように配置されているので、漏洩磁束の増大や磁気抵抗の増大による磁気効率の低下によりチョークコイル自体の特性を劣化させる要因になっていた（特許文献２）。
【０００６】
そこで、本発明は上記の問題点を解決し、コモンモードチョークコイルの構造であるが安定したノーマルモードノイズを抑制する特性を兼ね備え、安価で、生産性の高いラインフィルタを提供しようというものである。
【０００７】
【課題を解決するための手段】
上記課題を解決するには、請求項１に記載の発明のように、ロ字形の閉磁路磁芯と、前記閉磁路磁芯の一辺の磁脚部に嵌入された２個のボビンと、前記ボビンにはそれぞれコイルが巻回され、前記磁脚部と対向した他磁脚部を前記コイルの外周面に配置し、前記ボビンの間を仕切るように差し込まれたＵ字形のセンター磁芯と、前記センター磁芯の開口部の内側近傍に対面した一対の凸部を備え、前記磁脚部の側面を前記センター磁芯の凹部の底面に対面するように配置するとともに、前記センター磁芯の前記開口部近傍の凸部が対面して前記閉磁路磁芯の他磁脚部を挟むように配置しラインフィルタを構成することにより達成できる。
【０００８】
また、前記ラインフィルタにおいて、請求項２に記載の発明のように、前記センター磁芯の前記凸部の奥行寸法を、この凸部と対面する前記閉磁路磁芯の前記他磁脚部の断面厚さ寸法以上とすることによりさらに磁気効率や漏洩磁束の問題を解決できる。
【０００９】
そして、前記ラインフィルタにおいて、請求項３に記載の発明のように、前記ボビンの前記閉磁路磁芯と対面するつばの面に前記閉磁路磁芯の取付位置決め係止部と、前記ボビンの前記センター磁芯と対面するつばの面に前記センター磁芯の位置決係止部とを設けたり、請求項４に記載の発明のように、前記センター磁芯を前記ボビンの間に差し込み所定の位置まで挿入係止後、前記ボビンと前記閉磁路磁芯およびセンター磁芯を一体に固定するコアカバーを備えることにより磁気空隙の安定化や生産性向上などの問題を解決することができる。
【００１０】
また、前記ラインフィルタにおいて、請求項５に記載の発明のように、前記センター磁芯を高絶縁性を有するニッケル系フェライトまたはフェライト粉を樹脂で成形したフェライト樹脂、または、絶縁樹脂でカバーをすることによりコロナ放電による絶縁低下の問題を解決できる。
【００１１】
【発明の実施の形態】
次に、本発明の実施の形態を図面に従って説明する。
図１は、本発明の実施の形態におけるラインフィルタの斜視図。図２は、図１の側面断面図。図３は、図１の分解斜視図。図４は、図３をさらに詳しく示す分解斜視図。図５は、本発明の変形例を示すラインフィルタの斜視図。図６は、本発明に係るラインフィルタのノーマルモードノイズに起因する磁束の流れを示す磁気回路図。図７は、本発明に係るラインフィルタの使用時のノーマルモードノイズの伝播を示す電気回路図。図８は、本発明に係るラインフィルタのコモンモードノイズに起因する磁束の流れを示す磁気回路図。図９は、本発明に係るラインフィルタの使用時のコモンモードノイズの伝播を示す電気回路図。図１０は、本発明に係るラインフィルタと従来仕様のラインフィルタのノーマルモードにおける重畳電流−インダクタンス特性図。
【００１２】
図１〜図３において、本発明の実施の形態に係るラインフィルタは、閉磁路磁芯１０はロ字形で形成されており、その１辺の磁脚部１１にコイル２０、２１がそれぞれ巻回されたボビン３０、３１が取付られ、さらに、前記磁脚部１１と対向した他磁脚部１２は、コイル２０、２１の外周面方に配置されている。また、ボビン３０と３１の間には、Ｕ字形のセンター磁芯４０がボビン３０と３１を仕切るように挿入され、さらに、閉磁路磁芯１０の磁脚部１１以外の他磁脚部１２と側磁脚部１３、１４の３辺を覆うようにコ字形のコアカバー５０が取り付けられている。
【００１３】
この構成において詳しくは、センター磁芯４０の開口部４１の内側近傍に、奥行寸法（Ａ）が他磁脚部１２の断面厚さ寸法（Ｂ）以上で、ほぼ左右対称な形状を呈する凸部４２、４３が設けられている。このように、センター磁芯４０は凸部４２、４３を設けてあることにより、センター磁芯４０の開口部寸法（Ｃ）はその底幅寸法（Ｄ）より小さく設定されている。これにより、磁脚部１１はセンター磁芯４０の底面４４と底部近傍の側面４５、４６の３面と対面するが、その磁脚部１１と底部近傍の側面４５、４６とのそれぞれの空隙（Ｅ１）、（Ｅ２）はほぼ等しく、また、磁脚部１１と底面４４との空隙（Ｆ）よりも大きく設定されている。なお、このように閉磁路磁芯１０とセンター磁芯４０を配置することにより磁束の通過する箇所の一定化が図れ、それにより低損失で安定した磁気回路を形成することができる。
【００１４】
ここにおいて、ボビン３０、３１の側脚部１３、１４と対面するそれぞれのつば面に図４に示すように、それぞれが側脚部１３、１４とがたなく嵌合できる十字形溝状の係止部ａが設けられている。さらに、ボビン３０、３１のセンター磁芯４０と対面するつば面にセンター磁芯４０の外幅とがたなく嵌合する係止部ｂ、ｃ、ｄが設けられており、この係止部ｂ、ｃ、ｄは十字形溝状の係止部ａのセンター基準線ＸおよびＹと一致する線上にそれぞれ配置されている。なお、ｅはこの実施の形態の変形で使用するためのセンター磁芯４０の係止部で、例えば、図５に示すように端子１６０が閉磁路磁芯１０の磁脚部１１と他磁脚部１２が形成する平面に対して垂直に引出したものとする場合、センター磁芯４０を前記の方法と同様にｃ、ｂ、ｅで係止すれば容易に入力・出力端子の引出方向を変えたラインフィルタを得ることができる。また、前述したそれぞれの実施の形態の説明において、ボビンのつば部に設けたセンター磁芯の位置決め係止部は、センター磁芯の外郭部としたが、これをセンター磁芯の内側すなわち凹部に設けてもよい。なお、図４における線ｆは、ボビン３０、３１を閉磁路磁芯１０の磁脚部１１に取付するための分割部を表している。
【００１５】
この実施の形態の一例として、このセンター磁芯４０をボビン３０と３１の間に挿入し、所定の位置まで押し込んた状態では、閉磁路磁芯１０の磁脚部１１はセンター磁芯４０の底面４４と０．１〜０．３ｍｍの空隙（Ｆ）と、また、底部近傍の側面４５、４６とはそれぞれ０．１５〜０．３５ｍｍの空隙（Ｅ１、Ｅ２）で配置されるように設定されている。さらに、開口部４１内側近傍の凸部４２、４３は他磁脚部１２を０．０５〜０．２５ｍｍの空隙を有して挟むように配置されるように設定されている。
【００１６】
このような構成により、他磁脚部１２とセンター磁芯４０の開口部４１が交叉する近辺のコアカバー５０の断面部５１は、図２の断面図に示す如く、その内側凹部は他磁脚部１２を嵌入し、また、その両外側面は凸部４２、４３の開口部４１方の段部に嵌入されている。さらに、このように閉磁路磁芯１０とセンター磁芯４０と係合されたコアカバー５０の両側鉤部５２、５３は、ボビン３０、３１のつばの縁部に引掛けられた状態で係止されている。なお、コアカバー５０は強靱で弾性を有する合成樹脂で形成されているので、前記のボビン３０、３１に対する係止は強固な固定とすることがでる。これにより、閉磁路磁芯１０とセンター磁芯４０の相互の位置関係や空隙は固定された設定通りの磁気回路を形成をすることができる。
【００１７】
また、ボビン３０、３１の外側のつば部には端子６０、６１がそれぞれ圧入されて閉磁路磁芯１０の磁脚部１１に取り付けられコイル２０、２１が巻回されている。そして、そこに巻回されたコイル２０、２１は、閉磁路磁芯１０の磁脚部１１に逆位相になるように、例えば、お互いに反対方向に巻回し端子６０、６１に結線されている。なお、コイル３０と３１は分離することにより成形性や取付の作業性を良くする効果ががある。
【００１８】
前述のように構成することにより、ノーマルモードノイズの抑制は、図６、図７において、一方のコイル２０およびコイル２１より発生する磁束Ｅ、Ｆを、センター磁芯４０には互いに同方向になるように流すとともに、閉磁路磁芯１０には互いに逆方向になるように流し、閉磁路磁芯１０内で、磁束Ｅ、Ｆが互いに非相殺するようにしてノーマルモードノイズＧを抑制している。
また、コモンモードノイズの抑制は、図８、図９において、一方のコイル２０およびコイル２１より発生する磁束Ｅ、Ｆを、閉磁路磁芯１０内で、互いに同方向になるとともに、互いに非相殺するようにしてコモンモードノイズＨを抑制している。
【００１９】
図１０は、本発明に係るラインフィルタと従来技術（前述の後者タイプ）のラインフィルタのノーマルモード特性（重畳電流−インダクタンス）を比較して示したものである。この測定に使用した各ラインフィルタは、各部品のサイズや材質およびコイル仕様は同一とし、なお且つ、組立状態においてはセンター磁芯の開口部方で閉磁路磁芯との対面距離や空隙を変えたものである。詳しくは、本発明品の閉磁路磁芯の他磁脚部は、センター磁芯の開口部の凸部と両サイド０．１５ｍｍの空隙をもって配置したものである。一方、従来技術品の閉磁路磁芯の他磁脚部は、センター磁芯の開口部の端面より０．１ｍｍ、開口部内側面より両サイド０．３ｍｍの空隙を持って配置したものである。また、比較測定に使用したラインフィルタのコモンモード特性は、本発明品は５．２ｍＨであり、従来技術品は５．１ｍＨ（印加電圧：１０ＫＨｚ、０．１Ｖ）でほぼ同等の特性を有していた。この図９からも分かるように、本発明に係るラインフィルタは定格電流の１．４５％近辺まで従来技術品より遙かに高い安定したインダクタンスを得ることができることがわかる。
【００２０】
なお、コイルとセンター磁芯のコロナ放電による絶縁低下の問題解決するために、センター磁芯４０は絶縁性の高いニッケル系フェライトまたはフェライト粉を樹脂で成形したフェライト樹脂とするか、または、センター磁芯を絶縁樹脂でカバーをする方法がある。
【００２１】
【発明の効果】
以上説明したように、請求項１に記載した発明によると、ロ字形の閉磁路磁芯と、前記閉磁路磁芯の一辺の磁脚部に嵌入された２個のボビンと、前記ボビンにはそれぞれコイルが巻回され、前記磁脚部と対向した他磁脚部を前記コイルの外周面に配置し、前記ボビンの間を仕切るように差し込まれたＵ字形のセンター磁芯と、前記センター磁芯の開口部の内側近傍に対面した一対の凸部を備え、前記磁脚部の側面を前記センター磁芯の凹部の底面に対面するように配置するとともに、前記センター磁芯の前記開口部近傍の凸部を対面して前記閉磁路磁芯の他磁脚部を挟むように配置することにより、モンモードチョークコイルの構造であるが漏洩磁束を最小限に抑えた磁気効率が優れて安定したノーマルモードノイズを抑制する特性を兼ね備えたラインフィルタを提供することができる。
【００２２】
また、請求項２に記載した発明によると、前記センター磁芯の前記凸部の奥行寸法は、この凸部と対面する前記閉磁路磁芯の前記他磁脚部の断面厚さ寸法以上とすることにより、さらに前記ラインフィルタの磁気効率の向上や漏洩磁束低減を図ることができる。
【００２３】
なお、請求項３に記載した発明によると、前記ボビンの前記閉磁路磁芯と対面するつばの面に前記閉磁路磁芯の取付位置決め係止部と、前記ボビンの前記センター磁芯と対面するつばの面に前記センター磁芯の位置決係止部とを設けたり、請求項４に記載した発明よると、前記センター磁芯を前記ボビンの間に差し込み所定の位置まで挿入係止後、前記ボビンと前記閉磁路磁芯およびセンター磁芯を一体に固定するコアカバーを備えることにより、生産性の向上をして安価な前記ラインフィルタを提供することができる。
【００２４】
また、請求項５に記載した発明によれば、前記センター磁芯を高絶縁性を有するニッケル系フェライトまたはフェライト粉を樹脂で成形したフェライト樹脂、または、絶縁樹脂でカバーをすることによりコロナ放電による絶縁低下の起きない前記ラインフィルタを提供することができる。
【図面の簡単な説明】
【図１】本発明の実施の形態例を示すラインフィルタの斜視図である。
【図２】図１に示したラインフィルタの側面断面図である。
【図３】図１に示したラインフィルタの分解斜視図である。
【図４】図１のラインフィルタをさらに詳しく示した分解斜視図である。
【図５】本発明の実施の形態の変形例を示す斜視図である。
【図６】本発明に係るラインフィルタのノーマルモードノイズに起因する磁束の流れを示す磁気回路図である。
【図７】本発明に係るラインフィルタの使用時のノーマルモードノイズの伝播を示す電気回路図である。
【図８】本発明に係るラインフィルタのコモンモードノイズに起因する磁束の流れを示す磁気回路図である。
【図９】本発明に係るラインフィルタの使用時のコモンモードノイズの伝播を示す電気回路図である。
【図１０】本発明に係るラインフィルタの重畳電流−インダクタンス特性図である。
【符号の説明】
１０閉磁路磁芯
１１磁脚部
１２他磁脚部
２０、２１コイル
３０、３１ボビン
４０センター磁芯
４１（センター磁芯の）開口部
５０コアカバー
６０、６１端子[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a line filter that removes common mode noise and normal mode noise generated from electric circuits of various electronic devices.
[0002]
[Prior art]
Conventionally, a choke coil that basically has a common mode choke coil structure but also suppresses normal mode noise has been known.
As such a structure, two U-shaped magnetic cores face each other by using one coil bobbin in which two windings separated by an insulator on the outer periphery are wound in opposite phases. In addition, a choke coil that is assembled inside and outside of the bobbin to form a substantially closed magnetic path, between two windings on one side of the substantially closed magnetic path core, that is, between the U-shaped magnetic core. There is known a composite choke coil that suppresses a common mode noise and a normal mode in which a short-circuit magnetic path is formed by connecting an H-shaped plate-like bypass magnetic core to the same (for example, see Patent Document 1).
[0003]
Also, insert the through-hole of one coil bobbin wound so that the two windings separated by an insulator on the outer circumference are in opposite phases to one magnetic leg part of the closed magnetic circuit core. A choke coil formed with a magnetic path, wherein a U-shaped center core is inserted between two windings of the bobbin, and the bottom of the center core is one of the closed magnetic path cores. Common mode noise and normal mode in which the magnetic path is formed so that the leading edge of the opening of the center magnetic core faces the other magnetic leg of the closed magnetic circuit core with a gap. There is known a composite choke coil that suppresses noise (see, for example, Patent Document 2).
[0004]
[Patent Document 1]
JP-A-9-139317 [Patent Document 2]
Japanese Patent Laid-Open No. 2001-110654
[Problems to be solved by the invention]
However, any of the above-described conventional techniques has problems as described later.
That is, since the magnetic core forming the closed magnetic path is a split type, a gap is generated on the mating surfaces, and the leakage magnetic flux varies due to the variation in the gap, resulting in a large variation in the characteristics of the choke coil itself (Patent Document 1). In addition, since the front edge of the opening of the center magnetic core is disposed so as to face the other magnetic leg portion constituting one side of the closed magnetic path magnetic core with a gap, an increase in leakage magnetic flux and magnetic resistance This has been a factor of deteriorating the characteristics of the choke coil itself due to a decrease in magnetic efficiency due to an increase in the frequency (Patent Document 2).
[0006]
Accordingly, the present invention is to solve the above-described problems and provide a line filter that has a structure of a common mode choke coil but has a characteristic of suppressing stable normal mode noise, is inexpensive, and has high productivity. .
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, as in the invention described in claim 1, a closed-shaped magnetic path magnetic core having a square shape, two bobbins fitted in a magnetic leg portion on one side of the closed magnetic path magnetic core, A coil is wound around each bobbin, the other magnetic leg part facing the magnetic leg part is arranged on the outer peripheral surface of the coil, and a U-shaped center magnetic core inserted so as to partition the bobbin; A pair of convex portions facing the inside in the vicinity of the opening of the center magnetic core, the side surface of the magnetic leg portion is disposed so as to face the bottom surface of the concave portion of the center magnetic core, and the center magnetic core This can be achieved by arranging the line filter by arranging the convex portions in the vicinity of the opening so as to face each other and sandwich the other magnetic leg portion of the closed magnetic path core.
[0008]
Further, in the line filter, as in the invention according to claim 2, the depth dimension of the convex portion of the center magnetic core is set to a cross section of the other magnetic leg portion of the closed magnetic path magnetic core facing the convex portion. The problem of magnetic efficiency and leakage magnetic flux can be further solved by making the thickness dimension or more.
[0009]
And, in the line filter, as in the invention according to claim 3, the closed magnetic path magnetic core mounting positioning locking portion on the face of the bobbin facing the closed magnetic path magnetic core, and the bobbin The center magnetic core positioning locking portion is provided on the face of the collar facing the center magnetic core, or the center magnetic core is inserted between the bobbins as in the invention according to claim 4, at a predetermined position. By providing a core cover that integrally fixes the bobbin, the closed magnetic path magnetic core, and the center magnetic core after being inserted and locked, problems such as stabilization of the magnetic gap and improvement in productivity can be solved.
[0010]
Further, in the line filter, as in the invention according to claim 5, the center magnetic core is covered with a ferrite resin obtained by molding nickel-based ferrite or ferrite powder having high insulating properties with resin, or with an insulating resin. This can solve the problem of insulation deterioration due to corona discharge.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view of a line filter according to an embodiment of the present invention. FIG. 2 is a side sectional view of FIG. 3 is an exploded perspective view of FIG. FIG. 4 is an exploded perspective view showing FIG. 3 in more detail. FIG. 5 is a perspective view of a line filter showing a modification of the present invention. FIG. 6 is a magnetic circuit diagram showing the flow of magnetic flux due to the normal mode noise of the line filter according to the present invention. FIG. 7 is an electric circuit diagram showing normal mode noise propagation when the line filter according to the present invention is used. FIG. 8 is a magnetic circuit diagram showing the flow of magnetic flux due to the common mode noise of the line filter according to the present invention. FIG. 9 is an electric circuit diagram showing propagation of common mode noise when the line filter according to the present invention is used. FIG. 10 is a superimposed current-inductance characteristic diagram in the normal mode of the line filter according to the present invention and the conventional line filter.
[0012]
1 to 3, in a line filter according to an embodiment of the present invention, a closed magnetic path magnetic core 10 is formed in a square shape, and coils 20 and 21 are wound around a magnetic leg portion 11 on one side thereof. The other bobbin 30, 31 is attached, and the other magnetic leg portion 12 facing the magnetic leg portion 11 is arranged on the outer peripheral surface side of the coils 20, 21. Further, a U-shaped center magnetic core 40 is inserted between the bobbins 30 and 31 so as to partition the bobbins 30 and 31, and the magnetic leg portion 12 other than the magnetic leg portion 11 of the closed magnetic path magnetic core 10 and A U-shaped core cover 50 is attached so as to cover the three sides of the side magnetic leg portions 13 and 14.
[0013]
Specifically, in this configuration, a convex portion in the vicinity of the inside of the opening 41 of the center magnetic core 40 having a depth dimension (A) equal to or greater than the cross-sectional thickness dimension (B) of the other magnetic leg portion 12 and having a substantially bilaterally symmetric shape. 42 and 43 are provided. Thus, since the center magnetic core 40 is provided with the convex portions 42 and 43, the opening dimension (C) of the center magnetic core 40 is set smaller than the bottom width dimension (D). As a result, the magnetic leg portion 11 faces the three surfaces of the bottom surface 44 of the center magnetic core 40 and the side surfaces 45 and 46 near the bottom, but the gaps between the magnetic leg portion 11 and the side surfaces 45 and 46 near the bottom ( E1) and (E2) are substantially equal, and are set to be larger than the gap (F) between the magnetic leg portion 11 and the bottom surface 44. In addition, by arranging the closed magnetic path magnetic core 10 and the center magnetic core 40 in this way, it is possible to make the portion through which the magnetic flux passes constant, thereby forming a stable magnetic circuit with low loss.
[0014]
Here, as shown in FIG. 4, each of the rib faces facing the side legs 13, 14 of the bobbins 30, 31 has a cross-shaped groove-like engagement that can be fitted with the side legs 13, 14 without any problems. A stop a is provided. Further, locking portions b, c, and d are provided on the collar surfaces of the bobbins 30 and 31 that face the center magnetic core 40 so that the outer width of the center magnetic core 40 is fitted to each other. , C, d are respectively arranged on lines that coincide with the center reference lines X and Y of the cross-shaped groove-shaped locking part a. Note that e is a locking portion of the center magnetic core 40 for use in the modification of this embodiment. For example, as shown in FIG. 5, the terminal 160 has the magnetic leg portion 11 of the closed magnetic path magnetic core 10 and the other magnetic leg. When the center core 40 is locked with c, b, e in the same manner as described above, the input / output terminal extraction direction can be easily changed. A line filter can be obtained. In the description of each of the embodiments described above, the positioning and locking portion of the center core provided on the collar portion of the bobbin is the outer portion of the center core. It may be provided. A line f in FIG. 4 represents a divided portion for attaching the bobbins 30 and 31 to the magnetic leg portion 11 of the closed magnetic path magnetic core 10.
[0015]
As an example of this embodiment, when the center magnetic core 40 is inserted between the bobbins 30 and 31 and pushed to a predetermined position, the magnetic leg portion 11 of the closed magnetic path magnetic core 10 is the bottom surface of the center magnetic core 40. 44, 0.1 to 0.3 mm gap (F), and side surfaces 45 and 46 near the bottom are set to be 0.15 to 0.35 mm gap (E1, E2), respectively. ing. Further, the convex portions 42 and 43 in the vicinity of the inside of the opening 41 are set so that the other magnetic leg portion 12 is sandwiched with a gap of 0.05 to 0.25 mm.
[0016]
With such a configuration, the cross-sectional portion 51 of the core cover 50 in the vicinity where the other magnetic leg portion 12 and the opening 41 of the center magnetic core 40 intersect each other has an inner concave portion as shown in the cross-sectional view of FIG. The portion 12 is inserted, and both outer side surfaces thereof are inserted into the step portions of the convex portions 42 and 43 toward the opening 41. Further, the both side flanges 52 and 53 of the core cover 50 engaged with the closed magnetic path magnetic core 10 and the center magnetic core 40 in this way are locked in a state of being hooked on the edge portions of the bobbins 30 and 31. Has been. In addition, since the core cover 50 is formed of a tough and elastic synthetic resin, the locking to the bobbins 30 and 31 can be firmly fixed. Thereby, the mutual positional relationship and the space | gap of the closed magnetic path magnetic core 10 and the center magnetic core 40 can form the magnetic circuit as the setting fixed.
[0017]
Further, terminals 60 and 61 are press-fitted into the flange portions on the outside of the bobbins 30 and 31, respectively, and attached to the magnetic leg portion 11 of the closed magnetic path magnetic core 10, and the coils 20 and 21 are wound thereon. And the coils 20 and 21 wound there are wound in opposite directions to the magnetic leg portion 11 of the closed magnetic path core 10, for example, wound in opposite directions and connected to the terminals 60 and 61. . In addition, there exists an effect which improves the moldability and the workability | operativity of attachment by isolate | separating the coils 30 and 31. FIG.
[0018]
By configuring as described above, normal mode noise can be suppressed by causing the magnetic fluxes E and F generated from one of the coils 20 and 21 in the center magnetic core 40 to be in the same direction in FIGS. The normal mode noise G is suppressed by causing the magnetic fluxes E and F to cancel each other out in the closed magnetic path magnetic core 10. .
8 and 9, the magnetic fluxes E and F generated from one coil 20 and the coil 21 are in the same direction in the closed magnetic circuit core 10 and are not canceled each other. In this way, the common mode noise H is suppressed.
[0019]
FIG. 10 shows a comparison between normal mode characteristics (superimposed current-inductance) of the line filter according to the present invention and the line filter of the prior art (the above-mentioned latter type). Each line filter used for this measurement has the same size, material, and coil specifications for each component, and in the assembled state, the facing distance and air gap from the closed magnetic path magnetic core are changed in the opening of the center magnetic core. It is a thing. Specifically, the other magnetic leg portion of the closed magnetic path magnetic core of the present invention is arranged with a convex portion of the opening of the center magnetic core and a gap of 0.15 mm on both sides. On the other hand, the other magnetic leg portion of the closed magnetic path magnetic core of the prior art product is arranged with a gap of 0.1 mm from the end face of the opening of the center magnetic core and 0.3 mm on both sides from the inner side surface of the opening. The common mode characteristics of the line filter used for comparative measurement are 5.2 mH for the product of the present invention, and 5.1 mH (applied voltage: 10 KHz, 0.1 V) for the product of the prior art. It was. As can be seen from FIG. 9, the line filter according to the present invention can obtain stable inductance much higher than that of the prior art product up to around 1.45% of the rated current.
[0020]
In order to solve the problem of insulation deterioration due to corona discharge between the coil and the center magnetic core, the center magnetic core 40 is made of a highly insulating nickel-based ferrite or ferrite resin obtained by molding a resin with a resin, There is a method of covering the core with an insulating resin.
[0021]
【The invention's effect】
As described above, according to the invention described in claim 1, the closed-shaped magnetic path magnetic core having a square shape, the two bobbins fitted in the magnetic leg portions on one side of the closed magnetic path magnetic core, and the bobbin Each of the coils is wound, the other magnetic leg portion opposed to the magnetic leg portion is disposed on the outer peripheral surface of the coil, and a U-shaped center magnetic core inserted so as to partition the bobbin, and the center magnet A pair of convex portions facing the inner vicinity of the opening portion of the core, the side surface of the magnetic leg portion is disposed so as to face the bottom surface of the concave portion of the center magnetic core, and the vicinity of the opening portion of the center magnetic core By arranging the other magnetic leg part of the closed magnetic path core so as to face the convex part, the structure of the monmode choke coil is excellent and the magnetic efficiency with minimized leakage magnetic flux is stable. Combines normal mode noise suppression characteristics The line filter can be provided.
[0022]
According to the invention described in claim 2, the depth dimension of the convex portion of the center magnetic core is equal to or larger than the cross-sectional thickness dimension of the other magnetic leg portion of the closed magnetic path magnetic core facing the convex portion. As a result, the magnetic efficiency of the line filter can be further improved and the leakage magnetic flux can be reduced.
[0023]
According to the invention described in claim 3, the mounting positioning locking portion of the closed magnetic path magnetic core faces the collar surface of the bobbin facing the closed magnetic path magnetic core, and the center magnetic core of the bobbin faces. According to the invention described in claim 4, the center magnetic core is inserted between the bobbins and inserted and locked to a predetermined position. By providing a core cover that integrally fixes the bobbin, the closed magnetic path magnetic core, and the center magnetic core, the productivity can be improved and the inexpensive line filter can be provided.
[0024]
According to the invention described in claim 5, the center magnetic core is covered with a nickel resin having high insulation or a ferrite resin obtained by molding ferrite powder with a resin, or by corona discharge by covering with a resin. It is possible to provide the line filter that does not cause a decrease in insulation.
[Brief description of the drawings]
FIG. 1 is a perspective view of a line filter showing an embodiment of the present invention.
FIG. 2 is a side sectional view of the line filter shown in FIG.
3 is an exploded perspective view of the line filter shown in FIG. 1. FIG.
4 is an exploded perspective view showing the line filter of FIG. 1 in more detail. FIG.
FIG. 5 is a perspective view showing a modification of the embodiment of the present invention.
FIG. 6 is a magnetic circuit diagram showing a flow of magnetic flux caused by normal mode noise of the line filter according to the present invention.
FIG. 7 is an electric circuit diagram showing propagation of normal mode noise when the line filter according to the present invention is used.
FIG. 8 is a magnetic circuit diagram showing a flow of magnetic flux caused by common mode noise of the line filter according to the present invention.
FIG. 9 is an electric circuit diagram showing propagation of common mode noise when the line filter according to the present invention is used.
FIG. 10 is a superimposed current-inductance characteristic diagram of the line filter according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Closed magnetic path magnetic core 11 Magnetic leg part 12 Other magnetic leg parts 20, 21 Coil 30, 31 Bobbin 40 Center magnetic core 41 (Center magnetic core) opening 50 Core cover 60, 61 Terminal

Claims

A rectangular closed magnetic path magnetic core, two bobbins fitted on a magnetic leg portion on one side of the closed magnetic path magnetic core, and a coil around each of the bobbins, and another magnet facing the magnetic leg portion A leg portion is arranged on the outer peripheral surface of the coil, and includes a U-shaped center magnetic core inserted so as to partition the bobbin, and a pair of convex portions facing the inside of the opening of the center magnetic core. The side of the magnetic leg portion is arranged so as to face the bottom surface of the concave portion of the center magnetic core, and the convex portion near the opening of the center magnetic core faces the other magnetic leg of the closed magnetic path magnetic core. A line filter characterized by suppressing common mode noise and normal mode noise arranged so as to sandwich the section.

The line filter according to claim 1, wherein a depth dimension of the convex portion of the center magnetic core is equal to or larger than a cross-sectional thickness dimension of the other magnetic leg portion of the closed magnetic path magnetic core facing the convex portion.

Mounting and locking portion of the closed magnetic path magnetic core on the surface of the collar facing the closed magnetic path magnetic core of the bobbin, and positioning and locking of the center magnetic core on the surface of the collar facing the center magnetic core of the bobbin The line filter of Claim 1 or Claim 2 which provided the part.

The core cover is provided with a core cover that integrally fixes the bobbin, the closed magnetic path magnetic core, and the center magnetic core after the center magnetic core is inserted between the bobbins and inserted and locked to a predetermined position. The line filter described.

The line filter according to any one of claims 1 to 4, wherein the center magnetic core is covered with a nickel resin having high insulating properties or a ferrite resin obtained by molding a ferrite powder with a resin, or an insulating resin.