JP3658699B2

JP3658699B2 - Linear actuator

Info

Publication number: JP3658699B2
Application number: JP19104598A
Authority: JP
Inventors: 義博坪井; 尚石川
Original assignee: Sumitomo Metal Mining Co Ltd
Current assignee: Sumitomo Metal Mining Co Ltd
Priority date: 1998-06-22
Filing date: 1998-06-22
Publication date: 2005-06-08
Anticipated expiration: 2018-06-22
Also published as: JP2000014117A

Description

【０００１】
【発明の属する技術分野】
本発明は、磁気ヘッド部材等の搭載部材を直線方向へ移動させるリニアアクチュエータに係り、特に、駆動力の向上と高速かつスムーズに移動できるリニアアクチュエータの改良に関するものである。
【０００２】
【従来の技術】
この種のリニアアクチュエータとして、例えば、図４に示された部品にて構成されるものが知られている。すなわち、このリニアアクチュエータａは、鉄等の軟磁性材料で構成されかつ長方形状の平面部b1とこの長さ方向両端側から下方へ伸びる前面部b2並びに後面部b3を有する軟磁性上側ハウジングｂと、上記平面部b1の内面でその左右両縁部に取付けられた一対の帯状上側永久磁石ｃと、これ等永久磁石が取付けられた軟磁性上側ハウジングｂと対称形状を有する軟磁性下側ハウジングｄと、軟磁性上側並びに下側ハウジングｂ、ｄの前面部と後面部にその両端部が取付けられると共に上記永久磁石に対しそれぞれ平行に配置される一対の軟磁性磁気ヨークe1、e2と、筒部形状に形成されその筒部内略中央部に磁気ヘッド部材等の搭載部材ｆが取付けられると共にこの搭載部材ｆを中央にしてその両側の筒部内に上記軟磁性磁気ヨークe1、e2がそれぞれ遊嵌される駆動コイルｇとでその主要部が構成され、図５（Ａ）に示すような構造体に組立てられるものである。
【０００３】
尚、駆動コイルｇ筒部の外側には一対の係止部材g1、g2が付設されており、これ等係止部材g1、g2が図５（Ｂ）に示す棒状ガイドｈに係合して駆動コイルｇが直線方向へ移動可能に支持されるようになっている。また、このリニアアクチュエータにおいては搭載部材ｆ（但し、図５Ａ、Ｂでは図示せず）として長尺の磁気ヘッド部材が組込まれている関係上、軟磁性上側並びに下側ハウジングｂ、ｄの前面部と後面部には切欠部が形成されているが、これ等ハウジングｂ、ｄから外部へ出没することのない搭載部材が組込まれるものにおいては上記切欠部の形成が省略される場合もある。また、軟磁性上側ハウジングｂと軟磁性下側ハウジングｄについてもその一方が省略された構造のリニアアクチュエータも知られている。また、図５（Ａ）に示されたリニアアクチュエータのハウジングは一対の軟磁性上側並びに下側ハウジングｂ、ｄで構成されているが、予め図５（Ａ）のハウジング形状に成形された単一の軟磁性ハウジングで構成されたリニアアクチュエータも知られている。
【０００４】
【発明が解決しようとする課題】
ところで、図５（Ａ）に示されたリニアアクチュエータａにおいて上記永久磁石ｃで発生した磁束の大半は図５（Ｂ）に示すように対向側の磁気ヨークe1、e2へ導かれるが、その一部については軟磁性材料で構成された軟磁性ハウジングｂ、ｄの存在によりその平面部側へ漏れ易く、かつ、駆動コイルｇの中央部付近では図５（Ｂ）に示すように駆動コイルｇに鎖交する磁束の流線方向が他の部位と逆向きになっている。
【０００５】
このため、駆動コイルｇに鎖交する逆向きの磁束が存在する分、リニアアクチュエータａの駆動力が低下してしまう問題点があった。
【０００６】
また、上記軟磁性ハウジングｂ、ｄ平面部側への磁束の漏れは平面部の長さ方向に亘り存在し、かつ、その漏れ具合も長さ方向に亘って均一とは限らないため、リニアアクチュエータ中心部αを通る長さ方向（すなわち駆動コイルｇの移動方向）に亘る磁界分布もばらつき易かった。
【０００７】
このため、上記磁界分布のばらつきに起因して駆動コイルｇの移動方向に対するリニアアクチュエータの駆動力もばらつき易く、磁気ヘッド部材等搭載部材ｆを高速かつスムーズに移動することが困難となる問題点を有していた。
【０００８】
本発明はこの様な問題点に着目してなされたもので、その課題とするところは、上記永久磁石より生ずる磁束が有効に利用されるような構造を採ることにより駆動力の向上と高速かつスムーズに移動可能なリニアアクチュエータを提供することにある。
【０００９】
【課題を解決するための手段】
すなわち、請求項１に係る発明は、
矩形状平面部とこの長さ方向両端側から上方若しくは下方へ伸びる前面並びに後面部を有する軟磁性ハウジングと、
上記軟磁性ハウジングにおける矩形状平面部の長さ方向に亘りその内面かつ左右両縁部に互いに平行に取付けられた一対の帯状永久磁石と、
軟磁性ハウジングにおける前面並びに後面部にその両端部が取付けられると共に一対の帯状永久磁石に対し平行に配置された一対の軟磁性磁気ヨークと、
筒部形状に形成されこの筒部に搭載部材が取付けられると共に上記筒部内に一対の磁気ヨークがそれぞれ遊嵌されかつ筒部の開放方向に亘り移動可能に支持された駆動コイルを備え、
上記駆動コイルに取付けられた搭載部材が駆動コイルの移動に伴い軟磁性ハウジングの上記前面部と後面部間を進退するリニアアクチュエータを前提とし、
上記軟磁性ハウジングの矩形状平面部における永久磁石の取付け部以外の部位に低透磁率部を形成したことを特徴とするものである。
【００１０】
また、請求項２に係る発明は、
請求項１記載の発明に係るリニアアクチュエータを前提とし、
上記矩形状平面部における永久磁石の取付け部以外の部位に開口を設けて上記低透磁率部が形成されていることを特徴とし、
請求項３に係る発明は、
上記矩形状平面部における永久磁石の取付け部以外の部位に開口を設けかつこの開口を非磁性材料により閉止して上記低透磁率部が形成されていることを特徴とするものである。
【００１１】
そして、請求項１〜３記載の発明に係るリニアアクチュエータによれば、
軟磁性ハウジングの矩形状平面部における永久磁石の取付け部以外の部位に低透磁率部が形成されているため、永久磁石からの上記軟磁性ハウジングにおける矩形状平面部への磁束の漏れを大幅に低減させることが可能となる。
【００１２】
更に、矩形状平面部へ漏れる磁束が低減されたことにより、上記駆動コイルに鎖交する逆向きの磁束量も減少させることができ、かつ、駆動コイルの移動方向に対する磁界分布のばらつきも抑制させることが可能となる。
【００１３】
尚、請求項１〜３に係るリニアアクチュエータは、上述した軟磁性上側ハウジングと軟磁性下側ハウジングのいずれか一方を省略した構造のリニアアクチュエータに関するものであるが、以下に説明する請求項４〜６に係るリニアアクチュエータは軟磁性上側ハウジングと軟磁性下側ハウジングとでそのハウジングが構成されるリニアアクチュエータに関するものである。
【００１４】
すなわち、請求項４に係る発明は、
矩形状平面部とこの長さ方向両端側から下方へ伸びる上側前面並びに上側後面部を有する軟磁性上側ハウジングと、
上記軟磁性上側ハウジングにおける矩形状平面部の長さ方向に亘りその内面かつ左右両縁部に互いに平行に取付けられた一対の帯状上側永久磁石と、
矩形状平面部とこの長さ方向両端側から上方へ伸びると共に上記軟磁性上側ハウジングの上側前面部と上側後面部に位置整合された下側前面並びに下側後面部を有する軟磁性下側ハウジングと、
上記軟磁性下側ハウジングにおける矩形状平面部の長さ方向に亘りその内面かつ左右両縁部に互いに平行に配置されると共に一対の上記上側永久磁石に対しても平行に取付けられた一対の帯状下側永久磁石と、
軟磁性上側並びに下側ハウジングにおける上側並びに下側前面部と上側並びに下側後面部にその両端部が取付けられると共に上記上側並びに下側永久磁石に対しそれぞれ平行に配置された一対の軟磁性磁気ヨークと、
筒部形状に形成されこの筒部に搭載部材が取付けられると共に上記筒部内に一対の磁気ヨークがそれぞれ遊嵌されかつ筒部の開放方向に亘り移動可能に支持された駆動コイルを備え、
上記駆動コイルに取付けられた搭載部材が駆動コイルの移動に伴い軟磁性上側並びに下側ハウジングの上側並びに下側前面部と上側並びに下側後面部間を進退するリニアアクチュエータを前提とし、
上記軟磁性上側並びに下側ハウジングの各矩形状平面部における上側並びに下側永久磁石の取付け部以外の部位に低透磁率部をそれぞれ形成したことを特徴とするものである。
【００１５】
また、請求項５に係る発明は、
請求項４記載のリニアアクチュエータを前提とし、
上記軟磁性上側並びに下側ハウジングの各矩形状平面部における上側並びに下側永久磁石の取付け部以外の部位に開口を設けて上記低透磁率部が形成されていることを特徴とし、
請求項６に係る発明は、
上記軟磁性上側並びに下側ハウジングの各矩形状平面部における上側並びに下側永久磁石の取付け部以外の部位に開口を設けかつこの開口を非磁性材料により閉止して上記低透磁率部が形成されていることを特徴とするものである。
【００１６】
尚、請求項４〜６に係るリニアアクチュエータにおいて上記軟磁性上側ハウジングと軟磁性下側ハウジングについては、従来と同様に、別体の軟磁性上側並びに下側ハウジングでこれを構成してもよく、あるいは、請求項４〜６に係るリニアアクチュエータのハウジング形状に予め成形された単一の軟磁性ハウジングでこれを構成してもよく任意である。
【００１７】
【発明の実施の形態】
以下、本発明の実施の形態について図面を参照して詳細に説明する。
【００１８】
この実施の形態に係るリニアアクチュエータは請求項５に係る発明を具体化したものである。
【００１９】
まず、このリニアアクチュエータは、図１に示すように鉄等の軟磁性材料で構成されかつ長方形状の平面部１０とこの長さ方向両端側から下方へ伸びる前面部１１並びに後面部１２を有すると共に上記平面部１０の略中央部位に長方形状の開口１３が設けられた軟磁性上側ハウジング１と、上記平面部１０の内面でその左右両縁部に取付けられた一対の帯状上側永久磁石９と、これ等永久磁石９が取付けられた軟磁性上側ハウジング１と対称形状を有する軟磁性下側ハウジング２と、鉄等の軟磁性材料で構成されかつ上記軟磁性上側並びに下側ハウジング１、２の前面部と後面部にその両端部が取付けられると共に上記永久磁石９に対しそれぞれ平行に配置される一対の軟磁性磁気ヨーク３１、３２と、筒部形状に形成されその筒部内略中央部に磁気ヘッド部材等の搭載部材４が取付けられると共にこの搭載部材４を中央にしてその両側の筒部内に上記軟磁性磁気ヨーク３１、３２がそれぞれ遊嵌される駆動コイル５とでその主要部が構成され、図２（Ａ）に示すような構造体に組立てられるものである。
【００２０】
尚、駆動コイル５筒部の外側には従来と同様に一対の係止部材６１、６２が付設されており、これ等係止部材６１、６２が図２（Ｂ）に示す棒状ガイド７に係合して駆動コイル５が直線方向へ移動可能に片側支持されるようになっている。また、このリニアアクチュエータにおいても搭載部材４（但し、図２Ａ、Ｂでは図示せず）として長尺の磁気ヘッド部材が組込まれている関係上、軟磁性上側並びに下側ハウジング１、２の前面部と後面部に切欠部を形成しているが、これ等ハウジング１、２から外部へ出没することのない搭載部材が組込まれるものについては上記切欠部を省略してもよい。また、上記軟磁性下側ハウジング２については永久磁石９が取付けられた上記軟磁性上側ハウジング１と対象形状を有するハウジングが適用されているが、永久磁石９を取付けた軟磁性上側ハウジング１の構造が前後左右において対称性を具備するものであるなら、軟磁性上側ハウジング１と軟磁性下側ハウジング２について同一構造のハウジングでこれ等を構成してもよい。
【００２１】
そして、この実施の形態に係るリニアアクチュエータ１００によれば、軟磁性上側並びに下側ハウジング１、２の平面部１０に長方形状の開口１３が設けられているため、この開口１３部位の透磁率は上記平面部１０におけるその他の部位に較べて著しく低くなっている。
【００２２】
このため、図２（Ｂ）に示すように永久磁石９からの上記軟磁性上側並びに下側ハウジング１、２における平面部１０への磁束の漏れを大幅に低減させることが可能となり、かつ、上記駆動コイル５に鎖交する逆向きの磁束量も減少させることができると共に、駆動コイル５の移動方向に対する磁界分布のばらつきも抑制させることが可能となる。
【００２３】
従って、駆動力の大幅な向上が図れると共に、磁気ヘッド部材等搭載部材４を高速かつスムーズに移動させることが可能となる。
【００２４】
更に、上記軟磁性上側並びに下側ハウジング１、２の平面部１０に開口１３が設けられていることから、その分、各ハウジング重量の低減も図れるためリニアアクチュエータの軽量化が可能となる。
【００２５】
尚、上記開口１３を非磁性材料であるアルミニウム、銅等の金属あるいはナイロン、ポリプロピレン等の合成樹脂により閉止する構造を採ってもよい。
【００２６】
【実施例】
以下、本発明の実施例について具体的に説明する。
【００２７】
［実施例］
この実施例に係るリニアアクチュエータは、図１〜図２に示された実施の形態に係るリニアアクチュエータと同一の構造を有するものである。
【００２８】
尚、この実施例に係るリニアアクチュエータのハウジング寸法については、駆動コイル５移動方向の長さ寸法が４５ｍｍ、幅寸法が２２ｍｍ、高さ寸法が１４ｍｍに設定され、また、開口１３の長さ寸法が３４ｍｍ、幅寸法が８ｍｍにそれぞれ設定されている。また、４つの永久磁石９については、長さが４０ｍｍ、幅が７．２ｍｍ、厚さが２ｍｍで、最大磁気エネルギー積が６ＭＧＯｅ相当の希土類系帯状磁石が用いられている。また、リニアアクチュエータの中心部α（図２Ｂ参照）に関して点対称となるように４つの永久磁石９の着磁方向を考慮して配置している。
【００２９】
そして、この実施例に係るリニアアクチュエータの駆動コイル５に鎖交する磁束、すなわち、図２（Ｂ）に示すようにリニアアクチュエータの中心部αを通り駆動コイル５の移動方向に亘る磁界分布（磁束密度分布）を測定したところ図３のグラフ図に示すような結果が得られた。
【００３０】
［比較例］
比較例に係るリニアアクチュエータは、上記軟磁性上側並びに下側ハウジング１、２の平面部１０に開口１３が設けられていない点を除き実施例に係るリニアアクチュエータと同一である。
【００３１】
そして、この比較例に係るリニアアクチュエータについても実施例と同様に上記磁界分布（磁束密度分布）を測定した。
【００３２】
この結果も図３のグラフ図に示す。
【００３３】
そして、図３のグラフ図から明らかなように実施例に係るリニアアクチュエータは比較例に係るリニアアクチュエータと較べて上記磁界分布（磁束密度分布）が駆動コイル５の移動方向に亘り均一で、従って、磁気ヘッド部材等搭載部材４を高速かつスムーズに移動できることが確認された。
【００３４】
【発明の効果】
請求項１〜３記載の発明に係るリニアアクチュエータによれば、
軟磁性ハウジングの矩形状平面部における永久磁石の取付け部以外の部位に低透磁率部が形成され、
また、請求項４〜６記載の発明に係るリニアアクチュエータによれば、
軟磁性上側並びに下側ハウジングの各矩形状平面部における上側並びに下側永久磁石の取付け部以外の部位に低透磁率部が形成されているため、
永久磁石からの上記軟磁性ハウジングにおける矩形状平面部への磁束の漏れを大幅に低減させることが可能となり、かつ、矩形状平面部へ漏れる磁束が低減されたことにより上記駆動コイルに鎖交する逆向きの磁束量も減少させることができると共に駆動コイルの移動方向に対する磁界分布のばらつきも抑制させることが可能となる。
【００３５】
従って、駆動力の大幅な向上が図れると共に、磁気ヘッド部材等の搭載部材を高速かつスムーズに移動させることが可能となる効果を有する。
【図面の簡単な説明】
【図１】実施の形態に係るリニアアクチュエータの構成部品の概略斜視図。
【図２】図２（Ａ）は実施の形態に係るリニアアクチュエータの概略斜視図、図２（Ｂ）は図２（Ａ）のＢ−Ｂ面断面図。
【図３】実施例並びに比較例に係るリニアアクチュエータの駆動コイルの移動方向とその磁束密度との関係を示すグラフ図。
【図４】従来例に係るリニアアクチュエータの構成部品の概略斜視図。
【図５】図５（Ａ）は従来例に係るリニアアクチュエータの概略斜視図、図５（Ｂ）は図５（Ａ）のＢ−Ｂ面断面図。
【符号の説明】
１軟磁性上側ハウジング
２軟磁性下側ハウジング
５駆動コイル
９永久磁石
１０平面部
１１前面部
１２後面部
１３開口
３１軟磁性磁気ヨーク
３２軟磁性磁気ヨーク
１００リニアアクチュエータ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a linear actuator that moves a mounting member such as a magnetic head member in a linear direction, and more particularly, to an improvement in a driving force and a linear actuator that can move smoothly at high speed.
[0002]
[Prior art]
As this type of linear actuator, for example, one constituted by the components shown in FIG. 4 is known. That is, the linear actuator a includes a soft magnetic upper housing b made of a soft magnetic material such as iron and having a rectangular plane portion b1, a front portion b2 extending downward from both ends in the length direction, and a rear portion b3. A pair of belt-like upper permanent magnets c attached to the left and right edges on the inner surface of the flat part b1, and a soft magnetic lower housing d having a symmetrical shape with the soft magnetic upper housing b to which these permanent magnets are attached. A pair of soft magnetic magnetic yokes e1, e2 whose both ends are attached to the front and rear surface portions of the soft magnetic upper and lower housings b, d and parallel to the permanent magnets, and a cylindrical portion A mounting member f such as a magnetic head member is attached to a substantially central portion of the cylindrical portion, and the soft magnetic magnetic yokes e1 and e2 are provided in the cylindrical portions on both sides of the mounting member f with the mounting member f in the center. The main part is composed of the loosely-fitted drive coil g, and is assembled into a structure as shown in FIG.
[0003]
A pair of locking members g1 and g2 are attached to the outer side of the drive coil g cylindrical portion, and these locking members g1 and g2 are engaged with the rod-shaped guide h shown in FIG. The coil g is supported so as to be movable in the linear direction. Further, in this linear actuator, since a long magnetic head member is incorporated as a mounting member f (not shown in FIGS. 5A and 5B), the soft magnetic upper side and the front portions of the lower housings b and d are installed. In the rear surface portion, a notch is formed. However, in the case where a mounting member that does not protrude outside from the housings b and d is incorporated, the formation of the notch may be omitted. A linear actuator having a structure in which one of the soft magnetic upper housing b and the soft magnetic lower housing d is omitted is also known. Further, the linear actuator housing shown in FIG. 5 (A) is composed of a pair of soft magnetic upper and lower housings b and d. However, the linear actuator is previously molded into the housing shape shown in FIG. 5 (A). A linear actuator composed of a soft magnetic housing is also known.
[0004]
[Problems to be solved by the invention]
Incidentally, most of the magnetic flux generated by the permanent magnet c in the linear actuator a shown in FIG. 5A is guided to the opposing magnetic yokes e1 and e2, as shown in FIG. 5B. The portion is easily leaked to the flat portion side due to the presence of the soft magnetic housings b and d made of a soft magnetic material, and in the vicinity of the central portion of the drive coil g, the drive coil g is formed as shown in FIG. The streamline direction of the interlinkage magnetic flux is opposite to that of other parts.
[0005]
For this reason, there is a problem that the driving force of the linear actuator a is reduced by the presence of the reverse magnetic flux interlinking with the driving coil g.
[0006]
In addition, since the leakage of magnetic flux to the plane part side of the soft magnetic housings b and d exists in the length direction of the plane part, and the leakage state is not always uniform in the length direction, the linear actuator The magnetic field distribution along the length direction passing through the central portion α (that is, the moving direction of the drive coil g) was also likely to vary.
[0007]
For this reason, the driving force of the linear actuator with respect to the moving direction of the driving coil g easily varies due to the variation in the magnetic field distribution, and it is difficult to move the mounting member f such as the magnetic head member smoothly at high speed. Was.
[0008]
The present invention has been made paying attention to such problems, and the problem is to improve the driving force and increase the speed by adopting a structure in which the magnetic flux generated from the permanent magnet is effectively used. An object of the present invention is to provide a linear actuator that can move smoothly.
[0009]
[Means for Solving the Problems]
That is, the invention according to claim 1
A soft magnetic housing having a rectangular planar portion and a front surface and a rear surface portion extending upward or downward from both ends in the length direction;
A pair of band-like permanent magnets attached in parallel to each other on the inner surface and the left and right edges of the rectangular flat portion in the soft magnetic housing;
A pair of soft magnetic yokes whose both ends are attached to the front surface and rear surface portion of the soft magnetic housing and arranged in parallel to the pair of band-shaped permanent magnets;
A mounting member is formed in the shape of the cylindrical portion, and a mounting member is attached to the cylindrical portion, and a pair of magnetic yokes are loosely fitted in the cylindrical portion, and are provided so as to be movable in the opening direction of the cylindrical portion,
Assuming that the mounting member attached to the drive coil is a linear actuator that moves back and forth between the front and rear surfaces of the soft magnetic housing as the drive coil moves,
A low magnetic permeability portion is formed in a portion other than the attachment portion of the permanent magnet in the rectangular flat portion of the soft magnetic housing.
[0010]
The invention according to claim 2
Based on the linear actuator according to the invention of claim 1,
The low magnetic permeability portion is formed by providing an opening in a portion other than the attachment portion of the permanent magnet in the rectangular planar portion,
The invention according to claim 3
The low-permeability portion is formed by providing an opening in a portion of the rectangular flat portion other than the permanent magnet mounting portion and closing the opening with a nonmagnetic material.
[0011]
And according to the linear actuator which concerns on invention of Claims 1-3,
Since the low magnetic permeability portion is formed in a portion other than the permanent magnet mounting portion in the rectangular flat portion of the soft magnetic housing, the leakage of magnetic flux from the permanent magnet to the rectangular flat portion in the soft magnetic housing is greatly reduced. It can be reduced.
[0012]
Further, since the magnetic flux leaking to the rectangular plane portion is reduced, the amount of magnetic flux in the reverse direction linked to the drive coil can be reduced, and the variation in the magnetic field distribution with respect to the direction of movement of the drive coil is also suppressed. It becomes possible.
[0013]
In addition, although the linear actuator which concerns on Claims 1-3 is related with the linear actuator of the structure which abbreviate | omitted any one of the soft-magnetic upper housing mentioned above or a soft-magnetic lower housing, Claims 4- demonstrated below 6 relates to a linear actuator in which a soft magnetic upper housing and a soft magnetic lower housing constitute the housing.
[0014]
That is, the invention according to claim 4
A soft magnetic upper housing having a rectangular planar portion and an upper front surface and an upper rear surface portion extending downward from both ends in the length direction;
A pair of strip-like upper permanent magnets attached in parallel to each other on the inner surface and the left and right edges of the rectangular planar portion in the soft magnetic upper housing;
A soft magnetic lower housing having a rectangular flat portion and a lower front surface and a lower rear surface portion which are extended upward from both ends in the longitudinal direction and aligned with the upper front surface portion and the upper rear surface portion of the soft magnetic upper housing; ,
A pair of strips arranged in parallel with each other on the inner surface and both left and right edges of the rectangular flat portion of the soft magnetic lower housing along the length direction and attached in parallel to the pair of upper permanent magnets A lower permanent magnet,
A pair of soft magnetic magnetic yokes whose both ends are attached to the upper side of the soft magnetic upper side and the lower housing, the lower front side, the upper side, and the lower rear side and are arranged in parallel to the upper and lower permanent magnets. When,
A mounting member is formed in the shape of the cylindrical portion, and a mounting member is attached to the cylindrical portion, and a pair of magnetic yokes are loosely fitted in the cylindrical portion, and are provided so as to be movable in the opening direction of the cylindrical portion,
Assuming that the mounting member attached to the drive coil is a linear actuator that moves back and forth between the soft magnetic upper side and the lower housing upper side and the lower front side and upper side and the lower rear side as the drive coil moves,
Low magnetic permeability portions are formed in portions other than the upper and lower permanent magnet mounting portions in the rectangular flat portions of the soft magnetic upper and lower housings, respectively.
[0015]
The invention according to claim 5
Based on the linear actuator according to claim 4,
The low magnetic permeability portion is formed by providing an opening in a portion other than the upper and lower permanent magnet mounting portions in each rectangular flat portion of the soft magnetic upper and lower housings,
The invention according to claim 6
An opening is provided in a portion other than the upper and lower permanent magnet mounting portions in each rectangular flat portion of the soft magnetic upper and lower housings, and the opening is closed with a nonmagnetic material to form the low magnetic permeability portion. It is characterized by that.
[0016]
In the linear actuators according to claims 4 to 6, the soft magnetic upper housing and the soft magnetic lower housing may be constituted by separate soft magnetic upper and lower housings as in the prior art. Alternatively, the linear actuator according to any one of claims 4 to 6 may be configured by a single soft magnetic housing that is preliminarily formed in the shape of the housing.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0018]
The linear actuator according to this embodiment embodies the invention according to claim 5.
[0019]
First, as shown in FIG. 1, the linear actuator is made of a soft magnetic material such as iron and has a rectangular flat surface portion 10 and a front surface portion 11 and a rear surface portion 12 extending downward from both ends in the length direction. A soft magnetic upper housing 1 in which a rectangular opening 13 is provided at a substantially central portion of the flat portion 10; a pair of upper permanent magnets 9 attached to both left and right edges of the inner surface of the flat portion 10; A soft magnetic lower housing 2 having a symmetrical shape with the soft magnetic upper housing 1 to which these permanent magnets 9 are attached, and a front surface of the soft magnetic upper and lower housings 1 and 2 made of a soft magnetic material such as iron. And a pair of soft magnetic magnetic yokes 31 and 32 that are arranged in parallel to the permanent magnet 9 and both ends thereof are attached to the central portion and the rear surface portion, and a substantially central portion in the cylindrical portion. A mounting member 4 such as a magnetic head member is attached to the drive coil 5 and the soft magnetic magnetic yokes 31 and 32 are loosely fitted in the cylindrical portions on both sides of the mounting member 4 in the center. It is constructed and assembled into a structure as shown in FIG.
[0020]
A pair of locking members 61 and 62 are attached to the outside of the cylinder portion of the drive coil as in the prior art, and these locking members 61 and 62 are engaged with the rod-shaped guide 7 shown in FIG. In addition, the drive coil 5 is supported on one side so as to be movable in the linear direction. Also in this linear actuator, the long magnetic head member is incorporated as the mounting member 4 (not shown in FIGS. 2A and 2B), so that the upper side of the soft magnetic upper side and the front side of the lower housings 1 and 2 are incorporated. Although the notch is formed in the rear surface, the notch may be omitted for those in which a mounting member that does not protrude from the housings 1 and 2 is incorporated. The soft magnetic lower housing 2 has the same shape as the soft magnetic upper housing 1 to which the permanent magnet 9 is attached. The structure of the soft magnetic upper housing 1 to which the permanent magnet 9 is attached. However, the soft magnetic upper housing 1 and the soft magnetic lower housing 2 may be composed of housings having the same structure.
[0021]
According to the linear actuator 100 according to this embodiment, since the rectangular opening 13 is provided in the flat portion 10 of the soft magnetic upper side and the lower housings 1 and 2, the permeability of the opening 13 part is as follows. It is significantly lower than the other parts of the flat portion 10.
[0022]
For this reason, as shown in FIG. 2 (B), it is possible to significantly reduce the leakage of magnetic flux from the permanent magnet 9 to the flat portion 10 in the upper and lower housings 1 and 2, and the above-mentioned It is possible to reduce the amount of magnetic flux in the reverse direction interlinked with the drive coil 5 and to suppress variations in the magnetic field distribution with respect to the moving direction of the drive coil 5.
[0023]
Accordingly, the driving force can be greatly improved, and the mounting member 4 such as the magnetic head member can be moved at high speed and smoothly.
[0024]
Further, since the openings 13 are provided in the flat portions 10 of the soft magnetic upper and lower housings 1 and 2, the weight of each housing can be reduced accordingly, and thus the weight of the linear actuator can be reduced.
[0025]
The opening 13 may be closed with a nonmagnetic material such as aluminum or copper, or a synthetic resin such as nylon or polypropylene.
[0026]
【Example】
Examples of the present invention will be specifically described below.
[0027]
[Example]
The linear actuator according to this example has the same structure as the linear actuator according to the embodiment shown in FIGS.
[0028]
As for the housing dimensions of the linear actuator according to this embodiment, the length dimension in the moving direction of the drive coil 5 is set to 45 mm, the width dimension is set to 22 mm, the height dimension is set to 14 mm, and the length dimension of the opening 13 is set. 34 mm and the width dimension are set to 8 mm, respectively. For the four permanent magnets 9, rare earth-based strip magnets having a length of 40 mm, a width of 7.2 mm, a thickness of 2 mm, and a maximum magnetic energy product equivalent to 6 MGOe are used. Further, the four permanent magnets 9 are arranged in consideration of the magnetization directions so as to be point-symmetric with respect to the central portion α (see FIG. 2B) of the linear actuator.
[0029]
And the magnetic flux linked to the drive coil 5 of the linear actuator according to this embodiment, that is, the magnetic field distribution (magnetic flux) passing through the central portion α of the linear actuator and moving in the direction of movement of the drive coil 5 as shown in FIG. When the density distribution was measured, the results shown in the graph of FIG. 3 were obtained.
[0030]
[Comparative example]
The linear actuator according to the comparative example is the same as the linear actuator according to the embodiment except that the opening 13 is not provided in the planar portion 10 of the soft magnetic upper side and the lower housings 1 and 2.
[0031]
And also about the linear actuator which concerns on this comparative example, the said magnetic field distribution (magnetic flux density distribution) was measured similarly to the Example.
[0032]
This result is also shown in the graph of FIG.
[0033]
As is clear from the graph of FIG. 3, the magnetic field distribution (magnetic flux density distribution) of the linear actuator according to the embodiment is uniform over the moving direction of the drive coil 5 as compared with the linear actuator according to the comparative example. It was confirmed that the mounting member 4 such as a magnetic head member can be moved at high speed and smoothly.
[0034]
【The invention's effect】
According to the linear actuator which concerns on invention of Claims 1-3,
A low magnetic permeability portion is formed in a portion other than the attachment portion of the permanent magnet in the rectangular flat portion of the soft magnetic housing,
Moreover, according to the linear actuator which concerns on invention of Claims 4-6,
Since the low magnetic permeability portion is formed in a portion other than the upper and lower permanent magnet mounting portions in each rectangular flat portion of the soft magnetic upper and lower housings,
It is possible to significantly reduce the leakage of magnetic flux from the permanent magnet to the rectangular planar portion in the soft magnetic housing, and the magnetic flux leaking to the rectangular planar portion is reduced, thereby interlinking with the drive coil. The amount of magnetic flux in the reverse direction can be reduced, and the variation in magnetic field distribution with respect to the direction of movement of the drive coil can be suppressed.
[0035]
Therefore, the driving force can be greatly improved and the mounting member such as the magnetic head member can be moved at high speed and smoothly.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view of components of a linear actuator according to an embodiment.
2A is a schematic perspective view of the linear actuator according to the embodiment, and FIG. 2B is a cross-sectional view taken along the line BB in FIG. 2A.
FIG. 3 is a graph showing a relationship between a moving direction of a drive coil and a magnetic flux density of a linear actuator according to an example and a comparative example.
FIG. 4 is a schematic perspective view of components of a linear actuator according to a conventional example.
5A is a schematic perspective view of a linear actuator according to a conventional example, and FIG. 5B is a cross-sectional view taken along a line BB in FIG. 5A.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Soft magnetic upper housing 2 Soft magnetic lower housing 5 Drive coil 9 Permanent magnet 10 Planar part 11 Front surface part 12 Rear surface part 13 Opening 31 Soft magnetic magnetic yoke 32 Soft magnetic magnetic yoke 100 Linear actuator

Claims

A soft magnetic housing having a rectangular planar portion and a front surface and a rear surface portion extending upward or downward from both ends in the length direction;
A pair of band-like permanent magnets attached in parallel to each other on the inner surface and the left and right edges of the rectangular flat portion in the soft magnetic housing;
A pair of soft magnetic yokes whose both ends are attached to the front surface and rear surface portion of the soft magnetic housing and arranged in parallel to the pair of band-shaped permanent magnets;
A mounting member is formed in the shape of the cylindrical portion, and a mounting member is attached to the cylindrical portion, and a pair of magnetic yokes are loosely fitted in the cylindrical portion, and are provided so as to be movable in the opening direction of the cylindrical portion,
In the linear actuator in which the mounting member attached to the drive coil advances and retracts between the front surface portion and the rear surface portion of the soft magnetic housing as the drive coil moves.
A linear actuator, wherein a low magnetic permeability portion is formed in a portion of the soft magnetic housing other than a permanent magnet mounting portion in a rectangular flat portion.

2. The linear actuator according to claim 1, wherein the low magnetic permeability portion is formed by providing an opening in a portion of the rectangular flat portion other than the permanent magnet mounting portion.

2. The linear portion according to claim 1, wherein an opening is provided in a portion of the rectangular flat portion other than the attachment portion of the permanent magnet, and the opening is closed with a nonmagnetic material to form the low magnetic permeability portion. Actuator.

A soft magnetic upper housing having a rectangular planar portion and an upper front surface and an upper rear surface portion extending downward from both ends in the length direction;
A pair of strip-like upper permanent magnets attached in parallel to each other on the inner surface and the left and right edges of the rectangular planar portion in the soft magnetic upper housing;
A soft magnetic lower housing having a rectangular flat portion and a lower front surface and a lower rear surface portion which are extended upward from both ends in the longitudinal direction and aligned with the upper front surface portion and the upper rear surface portion of the soft magnetic upper housing; ,
A pair of strips arranged in parallel with each other on the inner surface and both left and right edges of the rectangular flat portion of the soft magnetic lower housing along the length direction and attached in parallel to the pair of upper permanent magnets A lower permanent magnet,
A pair of soft magnetic magnetic yokes whose both ends are attached to the upper side of the soft magnetic upper side and the lower housing, the lower front side, the upper side, and the lower rear side and are arranged in parallel to the upper and lower permanent magnets. When,
A mounting member is formed in the shape of the cylindrical portion, and a mounting member is attached to the cylindrical portion, and a pair of magnetic yokes are loosely fitted in the cylindrical portion, and are provided so as to be movable in the opening direction of the cylindrical portion,
In the linear actuator in which the mounting member attached to the drive coil moves back and forth between the soft magnetic upper side and the lower housing upper side and the lower front side and upper side and the lower rear side as the drive coil moves,
A linear actuator characterized in that low magnetic permeability portions are formed in portions other than the upper and lower permanent magnet mounting portions in each of the rectangular flat portions of the soft magnetic upper and lower housings.

5. The low magnetic permeability portion is formed by providing openings in portions other than the upper and lower permanent magnet mounting portions in each rectangular flat portion of the soft magnetic upper and lower housings. The linear actuator described.

An opening is provided in a portion other than the upper and lower permanent magnet mounting portions in each rectangular flat portion of the soft magnetic upper and lower housings, and the opening is closed with a nonmagnetic material to form the low magnetic permeability portion. The linear actuator according to claim 4, wherein the linear actuator is provided.