JP4075441B2

JP4075441B2 - Manufacturing method of motor rotor

Info

Publication number: JP4075441B2
Application number: JP2002116256A
Authority: JP
Inventors: 靖治竹綱; 博佐藤; 靖西隈
Original assignee: Toyota Motor Corp
Current assignee: Toyota Motor Corp
Priority date: 2002-04-18
Filing date: 2002-04-18
Publication date: 2008-04-16
Anticipated expiration: 2022-04-18
Also published as: JP2003319620A

Description

【０００１】
【発明の属する技術分野】
この発明は、電動機ロータの製造方法に関し、特に、電気自動車などの電動機で用いられる電動機ロータの製造方法に関するものである。
【０００２】
【従来の技術】
近年、電動機を駆動源とした電気自動車や、電動機とガソリンエンジンなど複数種類の駆動源を有する、いわゆるハイブリッドカーが実用化されてきている。このような電気自動車などには、駆動源としての機能と、発電機としての機能を有する電動機が搭載されている。
【０００３】
電動機は回転可能な電動機ロータを有する。電動機ロータは、通常、磁性体からなるロータコアと、そのロータコアに接触する磁石とを有する構造とされる。
【０００４】
電動機ロータの製造方法は、たとえば特開平７−１７７７１２号公報に開示されている。上記公報に開示された電動機ロータでは、ロータコアとしてのヨークと、永久磁石とが焼結により接合されている。
【０００５】
【発明が解決しようとする課題】
上記公報に開示された製造方法では、永久磁石の粉末成形体と、ロータコア（ヨーク）の粉末成形体とをそれぞれ別々の工程で作製する。ロータコアの粉末成形体は孔を有する。このロータコアの粉末成形体の孔内に磁石の粉末成形体を挿入し、高温で焼結することにより、磁石をロータコアに接合させる。
【０００６】
上述のような方法では、焼結して製造したロータコアと磁石の間に隙間が生じるという問題がある。このように、ロータコアと磁石との間に隙間が生じると、この隙間が磁気抵抗となり、モータの性能が低下する。具体的には、モータの効率が低下するとともに、モータのトルク変動が生じる。
【０００７】
そこで、この発明は上述のような問題点を解決するためになされたものであり、ロータコアと磁石との間の隙間をなくし、優れた特性を発揮することが可能な電動機ロータを提供することを目的とする。
【０００８】
【課題を解決するための手段】
この発明に従った電動機ロータの製造方法は、ロータコアと、そのロータコアと接触する磁石とを備えた電動機ロータの製造方法であって、ロータコアとなる第１の粉末と、第１の粉末に接触し、磁石となる第２の粉末とを含み、第１の粉末と第２の粉末とが接触した状態で圧縮されて成形された圧粉体を準備する工程と、圧粉体を焼結する工程とを備える。
【０００９】
このような工程を備えた電動機ロータの製造方法に従えば、成形体同士を接触させて焼結する製造方法に比べて、ロータコアとなる第１の粉末と、磁石となる第２の粉末とが接触した状態で圧縮されて圧粉体が成形される。そのため、接触面同士が噛み合うため、圧粉体を焼結して得られる電動機ロータでは、ロータコアと磁石との間の隙間がなくなる。その結果、磁気抵抗が低減すると同時に、均一な磁界が形成される。これにより、モータの効率が向上するとともに、トルク変動を減少させることができる。
【００１０】
また、圧粉体を準備する工程は、前記円筒状のロータコアの内周形状を規定する外壁部を有する円柱状の第１部材と、前記円筒状のロータコアの外周形状を規定する内壁部を有する円筒状の第３部材と、前記第１部材の外壁部と前記第３部材の内壁部との間の円環状空間に配置される円環状部材であって、前記磁石の所定形状に対応する孔を有し、前記第１部材の外壁部と前記第３部材の内壁部とに接触して前記円環状の軸方向に移動可能な第２部材と、前記第２部材の前記孔に対応する外形形状を有し、前記孔に嵌め合わされ、前記孔の中で摺動可能な第４部材と、を準備する第１工程と、前記第１部材と前記第３部材とで囲まれた領域に前記円環状空間が生じるように、第４部材は移動させずそのままにして前記第２部材を前記円環状の軸方向に移動させ、前記円環状空間内に、前記ロータコアとなる前記第１の粉末を充填し、前記第１の粉末を、前記第１部材と前記第２部材との間で囲まれた前記円環状空間内であって、かつ前記移動されていない前記第４部材を取り囲むように配置する第２工程と、前記円筒状のロータコアの外周形状と同じ形状の外壁部を有する円筒状の第５部材を準備し、前記第４部材を取り囲むようにして円環状に充填された前記第１の粉末の充填上面と、前記第１部材の上面とに、前記第５部材の底面を接触させ、前記第５部材の前記外壁部を前記第３部材の前記内壁部に接触させながら、前記第５部材をその円筒状の軸方向に移動させて前記第１の粉末を圧縮する工程であって、前記第１部材と前記第３部材との間の径方向の間隔距離を変えず、前記第５部材の前記底面で、前記充填上面と前記第１部材の上面と前記第４部材の上面とを、前記第５部材の円筒状の軸方向に押し下げ、前記第４部材は、前記第１部材、前記第２部材、前記第３部材および前記第５部材で囲まれた領域に残して、前記第１の粉末を圧縮して前記ロータコアを成形する第３工程と、前記第５部材を前記ロータコアから離して取り除き、続いて、前記第４部材を前記第２部材の前記孔の中で移動させて、前記第２部材と前記第４部材の頂面の高さを同一とするようにして、前記ロータコアから前記第４部材を引抜き、前記ロータコアに前記磁石の所定形状に対応する孔を形成する第４工程と、前記ロータコアに形成された孔内に前記第２の粉末を充填する第５工程と、再び前記第５部材を準備し、前記形成された孔に前記第２の粉末が充填された前記ロータコアの上面に、前記第５部材の底面を接触させ、前記第５部材の前記外壁部を前記第３部材の前記内壁部に接触させながら、前記第５部材をその円筒状の軸方向に移動させて、前記第２部材と前記第４部材の頂面の高さを同一としたまま、前記第１の粉末と前記第２の粉末とを圧縮し、前記圧粉体を得る第６工程と、を含む。この場合、ロータコア部の孔内に第２の粉末を充填した後、ロータコア部と第２の粉末とを圧縮することにより、ロータコア部内に磁石部が埋込まれ、実際の製品に即した形状の電動機ロータを製造することができる。
また、前記第２工程は、前記第１の粉末として、ニッケル−鉄粉末を用い、前記第５工程は、前記第２の粉末として、ネオジム−鉄−ホウ素粉末を用いることが好ましい。
【００１１】
また好ましくは、前記圧粉体を準備する工程は、前記第１工程において、外周部に凹部と凸部とが形成された前記第４部材と、前記第４部材に接触して前記第４部材の凹部と凸部とに嵌り合う凹部と凸部が内周部に形成された前記第２部材とを準備し、前記第２工程から前記第６工程を行うことで、前記第１の粉末を含み、前記磁石の所定形状に対応する孔であって内周部の表面に凹凸が形成された孔を有する前記ロータコアと、前記第２の粉末を含み、前記凹凸に嵌り合う外周部の形状を有する前記磁石とを含む前記圧粉体を準備する。この場合、ロータコア部と磁石部との接触面積が増加するため、第１および第２の粉末の絡まりが強固となり、ロータコア部と磁石部との間の隙間が減少する。
【００１２】
【発明の実施の形態】
以下、この発明の実施の形態について、図面を参照して説明する。
【００１３】
（実施の形態１）
図１は、この発明の実施の形態１に従って製造された電動機ロータの平面図である。図２は、図１中のＩＩ−ＩＩ線に沿った断面図である。図１を参照して、電動機ロータ１００は、ベース体としてのロータコア１と、ロータコア１に埋込まれた磁石２とを有する。図１で示す電動機ロータ１００は、いわゆる、磁石式の駆動用電動機（モータ）で用いられるものであり、このような磁石式のモータは、燃費向上を目的とした電気自動車およびハイブリッド車などに搭載される。ロータコア１はリング状（環状）であり、軟磁性粒子を焼結することにより形成されている。ロータコア１および磁石２は、ロータコア１の中心を回転軸として所定方向に回転する。
【００１４】
ロータコア１を構成する材料としては、たとえば、ニッケル−鉄合金が用いられる。これに、さまざまな添加物を添加することができる。
【００１５】
磁石２は、永久磁石により構成される。この永久磁石として、たとえばネオジム−鉄−ボロン焼結型磁石、フェライト磁石または希土類ボンド磁石などを用いることができる。
【００１６】
図２を参照して、ロータコア１は円筒状であり、その円筒の一部分に磁石２が埋込まれている。ロータコア１の長さと磁石２の長さは等しい。そのため、磁石２は、ロータコア１を貫通するように設けられる。ロータコア１で囲まれる空間内には、電動機の回転軸などが配置され、この回転軸を中心としてロータコア１および磁石２が回転する。
【００１７】
次に、図１および図２で示す電動機ロータの製造方法を図３〜図８に従って説明する。なお、図３〜図８は、図１中のＩＩＩ−ＩＩＩ線に沿った断面図である。まず、図３を参照して、第１工程として、第１部材１１、第２部材１２、第３部材１３および第４部材１４を準備する。第１部材１１と第２部材１２とは接触している。第２部材１２内に第４部材１４が嵌め合わされている。第４部材１４は、第２部材１２に対して接触して摺動することが可能である。第２部材１２に接触するように第３部材１３が設けられている。
【００１８】
図４を参照して、第２工程として、第２部材１２を矢印で示す方向に移動させる。これにより、第１部材１１と第３部材１３とで囲まれた領域に空間が生じる。この空間内に、ロータコアとなる第１の粉末２１を充填する。第１の粉末２１としては、たとえばニッケル−鉄粉末を用いることができる。第１の粉末２１は、第１部材１１と第２部材１３との間で囲まれた空間であって、かつ第４部材１４を取り囲むように配置される。
【００１９】
図５を参照して、第３工程として第１の粉末２１を第５部材１５で圧縮する。具体的には、第１部材１１と第３部材１３との間の距離を変えず、第５部材１５を、第１部材１１、第３部材１３、および第４部材１４と接触させながら第５部材１５で第１粉末２１を圧縮する。このとき、第４部材１４は、第１部材１１、第２部材１２、第３部材１３および第５部材１５で囲まれた領域に残す。これにより、第１の粉末２１が圧縮されてロータコア部２５が成形される。ロータコア部２５は、第１の粉末２１の圧粉体である。
【００２０】
図６を参照して、第４工程として、第５部材１５をロータコア部２５から離す。続いて、第４部材１４を矢印で示す方向に移動させる。ロータコア部２５から第４部材１４が引抜かれることにより、ロータコア部２５に孔２１ｈが形成される。
【００２１】
図７を参照して、第５工程として、ロータコア部２５の孔２１ｈ内に第２の粉末２２を充填する。第２の粉末２２は、永久磁石となる粉末であり、たとえばネオジム−鉄−ホウ素粉末を用いることができる。また、フェライト粉末でもよい。
【００２２】
図８を参照して、第６工程として、第１部材１１、第２部材１２、第３部材１３および第５部材１５を用いて、第１の粉末２１と第２の粉末２２とを圧縮する。このとき、第２部材１２と第４部材１４の頂面の高さを同一とする。このように、第１の粉末２１と第２の粉末２２を圧縮することにより、第１の粉末２１により構成され、ロータコアとなるロータコア部２５と、第１の粉末２１に接触し、第２の粉末２２を含み、磁石となる磁石部２６とにより構成される圧粉体２３を得ることができる。
【００２３】
最後に、圧粉体２３を温度８００℃〜１３００℃の条件で焼結することにより、図１および図２で示すロータコア１と磁石２により構成される電動機ロータ１００を得ることができる。
【００２４】
このような電動機ロータの製造方法に従えば、図３〜図８で示したように、第１の粉末２１と第２の粉末２２を接触させ、これらを圧縮することにより圧粉体２３を成形する。この圧粉体２３を焼結することでロータコア１と磁石２からなる電動機ロータ１００を得ることができるため、第１の粉末２１と第２の粉末２２との界面では、第１の粉末２１と第２の粉末２２とが十分に噛み合う。
【００２５】
すなわち、第１の粉末２１により構成されるロータコア部２５と、第２の粉末２２により構成される磁石部２６では、その界面で隙間がなくなり、ロータコア部２５から磁石部２６に近づくにつれて第１の粉末２１の割合が減少し、第２の粉末２２の割合が増加するようになる。そのため、ロータコアと磁石とが強固に結合するため、この部分での磁気抵抗が低減するとともに、均一な磁界を形成することができる。その結果、モータの効率が向上するとともに、トルク変動を減少させることができる。
【００２６】
また、ロータコア１と磁石２との間の密着性を向上させるために金属箔を入れるような技術に比べて、製造工程を増加させることなくロータコア１と磁石２との間の隙間をなくすことができる。さらに、上述のような金属箔を入れる技術では、ロータコア１と磁石２との間の隙間をなくするために金属箔の厚み、ロータコアの磁石を挿入するための孔および磁石の厚みの寸法を精度よく管理する必要がある。これに対して、本発明では、上述のような金属箔を挿入しないため、寸法を厳密に管理する必要がなくなり、製造が容易となる。
【００２７】
（実施の形態２）
図９は、この発明の実施の形態２に従った方法で製造された電動機ロータの平面図である。図１０は、図９のＸで囲んだ部分を拡大して示す平面図である。図９および図１０を参照して、この発明の実施の形態２に従った電動機ロータ１００では、ロータコア１の表面に凸部１ａと凹部１ｂとが形成されている。この凸部１ａと凹部１ｂで囲まれる領域に磁石２が埋込まれている。
【００２８】
磁石２は凸部２ａと凹部２ｂとを有し、ロータコア１の凸部１ａが磁石２の凹部２ｂに嵌り合う。同様に、ロータコア１の凹部１ｂに磁石２の凸部２ａが嵌り合う。なお、図１０では、凸部１ａおよび２ａならびに凹部１ｂおよび２ｂの形状は円弧状としたが、これに限らず、三角形状、鋸状、四角形状の凸部１ａおよび２ａならびに凹部１ｂおよび２ｂを形成してもよい。
【００２９】
図９および図１０で示す電動機ロータ１００の製造方法は、図３で示す第２および第４部材１２および１４の形状を実施の形態１と異ならせる。すなわち、第４部材１４に図１０で示すような凹部および凸部を形成する。これに対応して、第４部材１４と接触する第２部材１２の面にも、第４部材１４の凹部および凸部と嵌り合う凹部および凸部を形成する。これにより、図４および図５で示す工程において所定の空間に第１の粉末２１を充填し、この第１の粉末２１を第５部材１５で圧縮してロータコア部２５を形成した場合に、このロータコア部２５の表面に凸部および凹部が形成される。
【００３０】
第４部材１４をロータコア部２５から引抜いて、孔２１ｈを形成したときには、孔２１ｈの表面には、凹部および凸部が形成されている。孔２１ｈ内に第２の粉末２２を充填した後これらを圧縮することで、凸部および凹部を有する磁石部２６と、ロータコア部２５を備えた圧粉体２３を得ることができる。
【００３１】
その後、圧粉体２３を焼結すれば図９および図１０で示される電動機ロータを製造することができる。
【００３２】
このように構成された、この発明の実施の形態２に従って電動機ロータでは、実施の形態１に従った電動機ロータと同様の効果がある。
【００３３】
さらに、ロータコア１の凸部１ａおよび凹部１ｂと、磁石２の凹部２ｂおよび凸部２ａが互いに嵌り合っているため、磁石２の外周部とロータコア１の内周部との接触面積が増加する。そのため、圧粉体２３を成形するときのロータコア部２５と磁石部２６との接触面積が大きくなってこれらの絡まりが強固になる。その結果、ロータコア部２５と磁石部２６の間の空間をさらに減少させることができる。
【００３４】
以上、この発明の実施の形態について説明したが、ここで示した実施の形態はさまざまに変形することが可能である。まず、電動機ロータ１００の形状として、実施の形態１および２では、円筒状のロータコアに磁石が円周上に配置されているものを示したが、これに限られるものではない。すなわち、磁石２がロータコア１の中心から放射線状に延びるように形成してもよい。この場合、磁石２はロータコア１の半径方向に延びるように形成される。
【００３５】
さらに、磁石２の配置位置としては、実施の形態１および２ともロータコア１内に配置したが、これに限られるものではなく、ロータコア１の外周上に磁石２を配置して、磁石２の一部分をロータコア１の外側へ露出させてもよい。
【００３６】
また、ロータコア１の表面に磁石２を接触させるように配置してもよい。また、ロータコア上の広い面積に磁石２を配置して、磁石２をパンケーキ型としてもよい。
【００３７】
さらに、磁石２およびロータコア１の表面にさまざまな焼入れ、焼なましなどの熱処理を施してもよい。また、必要に応じて、ロータコア１および磁石２の表面にめっきなどの表面処理を施してもよい。
【００３８】
今回開示された実施の形態はすべての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は上記した説明ではなくて特許請求の範囲によって示され、特許請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。
【００３９】
【発明の効果】
この発明に従えば、ロータコア１と磁石２との間の隙間がほとんどない電動機ロータを提供することができる。
【図面の簡単な説明】
【図１】この発明の実施の形態１に従って製造された電動機ロータの平面図である。
【図２】図１中のＩＩ−ＩＩ線に沿った断面図である。
【図３】図１および図２で示す電動機ロータの製造方法の第１工程を示す断面図である。
【図４】図１および図２で示す電動機ロータの製造方法の第２工程を示す断面図である。
【図５】図１および図２で示す電動機ロータの製造方法の第３工程を示す断面図である。
【図６】図１および図２で示す電動機ロータの製造方法の第４工程を示す断面図である。
【図７】図１および図２で示す電動機ロータの製造方法の第５工程を示す断面図である。
【図８】図１および図２で示す電動機ロータの製造方法の第６工程を示す断面図である。
【図９】この発明の実施の形態２に従って製造された電動機ロータの平面図である。
【図１０】図９中のＸで囲んだ部分を拡大して示す平面図である。
【符号の説明】
１ロータコア、２磁石、１１第１部材、１２第２部材、１３第３部材、１４第４部材、１５第５部材、２１第１の粉末、２１ｈ孔、２２第２の粉末、２３圧粉体、２５ロータコア部、２６磁石部、１００電動機ロータ。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing an electric motor rotor, and more particularly to a method for manufacturing an electric motor rotor used in an electric motor such as an electric vehicle.
[0002]
[Prior art]
In recent years, an electric vehicle using an electric motor as a drive source and a so-called hybrid car having a plurality of types of drive sources such as an electric motor and a gasoline engine have been put into practical use. Such an electric vehicle or the like is equipped with an electric motor having a function as a drive source and a function as a generator.
[0003]
The electric motor has a rotatable motor rotor. An electric motor rotor is usually configured to have a rotor core made of a magnetic material and a magnet that contacts the rotor core.
[0004]
A method for manufacturing an electric motor rotor is disclosed in, for example, Japanese Patent Application Laid-Open No. 7-177712. In the motor rotor disclosed in the above publication, a yoke as a rotor core and a permanent magnet are joined by sintering.
[0005]
[Problems to be solved by the invention]
In the manufacturing method disclosed in the above publication, a permanent magnet powder compact and a rotor core (yoke) powder compact are produced in separate steps. The powder compact of the rotor core has holes. The magnet powder compact is inserted into the hole of the rotor core powder compact and sintered at a high temperature to join the magnet to the rotor core.
[0006]
In the method as described above, there is a problem in that a gap is generated between the rotor core manufactured by sintering and the magnet. As described above, when a gap is generated between the rotor core and the magnet, the gap becomes a magnetic resistance, and the performance of the motor is deteriorated. Specifically, the motor efficiency decreases and the motor torque fluctuates.
[0007]
Accordingly, the present invention has been made to solve the above-described problems, and it is an object of the present invention to provide an electric motor rotor that can eliminate the gap between the rotor core and the magnet and exhibit excellent characteristics. Objective.
[0008]
[Means for Solving the Problems]
A method for manufacturing an electric motor rotor according to the present invention is an electric motor rotor manufacturing method including a rotor core and a magnet that contacts the rotor core, the first powder serving as the rotor core, and the first powder being in contact with the first powder. A step of preparing a green compact that is compressed and molded in a state where the first powder and the second powder are in contact with each other, and a step of sintering the green compact. With.
[0009]
According to the method for manufacturing an electric motor rotor including such a process, the first powder that becomes the rotor core and the second powder that becomes the magnet are compared with the manufacturing method in which the compacts are brought into contact with each other and sintered. The green compact is formed by compression in the contact state. For this reason, the contact surfaces mesh with each other, so that there is no gap between the rotor core and the magnet in the motor rotor obtained by sintering the green compact. As a result, the magnetic resistance is reduced and a uniform magnetic field is formed. As a result, the efficiency of the motor can be improved and the torque fluctuation can be reduced.
[0010]
The step of preparing the green compact has a columnar first member having an outer wall that defines the inner peripheral shape of the cylindrical rotor core, and an inner wall that defines the outer peripheral shape of the cylindrical rotor core. A cylindrical third member, and an annular member disposed in an annular space between the outer wall portion of the first member and the inner wall portion of the third member, the hole corresponding to a predetermined shape of the magnet A second member that contacts the outer wall portion of the first member and the inner wall portion of the third member and is movable in the annular axial direction, and an outer shape corresponding to the hole of the second member shaped, is fitted into the hole, the a region surrounded by a first step of preparing a fourth member slidable within said bore, said first member and said third member so that the annular space occurs, the leave to the second member of the annular fourth member is not moved Is moved in a direction, the annularly space, filled with the first powder of said rotor core, said first powder, the circle enclosed between said first member and said second member a in the annular space, and a second step of placing so as to surround the fourth member which is not the mobile, cylindrical fifth member having an outer wall portion of the same shape as the outer peripheral shape of the cylindrical rotor core The bottom surface of the fifth member is brought into contact with the top surface of the first powder filled in an annular shape so as to surround the fourth member and the top surface of the first member, A step of compressing the first powder by moving the fifth member in a cylindrical axial direction while bringing the outer wall portion of the five member into contact with the inner wall portion of the third member, without changing the first member a radial spacing distance between the third member, Serial in the bottom surface of the fifth member, wherein the filling upper surface and the upper surface of the first member and the upper surface of said fourth member, pushed axially cylindrical of the fifth member, said fourth member, said first 1 member, said second member, leaving the region surrounded by the third member and said fifth member, and a third step of forming the rotor core by compressing said first powder, the fifth member The first member is removed away from the rotor core, and then the fourth member is moved in the hole of the second member so that the top surfaces of the second member and the fourth member have the same height. A fourth step of drawing the fourth member from the rotor core and forming a hole corresponding to a predetermined shape of the magnet in the rotor core; and a second step of filling the second powder in the hole formed in the rotor core. 5 steps and preparing the fifth member again, the formed While the bottom surface of the fifth member is brought into contact with the upper surface of the rotor core filled with the second powder in the hole, the outer wall portion of the fifth member is brought into contact with the inner wall portion of the third member, by moving the fifth member in the axial direction of the cylindrical shape, the second member of the height of the top surface of the fourth member while the same compression and the second powder and the first powder And a sixth step of obtaining the green compact. In this case, after the second powder is filled in the hole of the rotor core portion, the rotor core portion and the second powder are compressed, so that the magnet portion is embedded in the rotor core portion, and the shape conforms to the actual product. An electric motor rotor can be manufactured.
The second step preferably uses nickel-iron powder as the first powder, and the fifth step uses neodymium-iron-boron powder as the second powder.
[0011]
Preferably, in the step of preparing the green compact, in the first step, the fourth member having a concave portion and a convex portion formed on an outer peripheral portion thereof, and the fourth member in contact with the fourth member. Preparing the concave member and the second member in which the convex portion is formed on the inner peripheral portion, and performing the sixth step to the sixth step, thereby preparing the first powder. A rotor core having a hole corresponding to a predetermined shape of the magnet and having a hole formed on the surface of the inner periphery, and a shape of the outer periphery including the second powder and fitting to the unevenness. wherein preparing a green compact comprising said magnet having. In this case, since the contact area between the rotor core portion and the magnet portion increases, the entanglement of the first and second powders becomes strong, and the gap between the rotor core portion and the magnet portion decreases.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0013]
(Embodiment 1)
FIG. 1 is a plan view of an electric motor rotor manufactured according to Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. Referring to FIG. 1, an electric motor rotor 100 includes a rotor core 1 as a base body and a magnet 2 embedded in the rotor core 1. The motor rotor 100 shown in FIG. 1 is used in a so-called magnet-type driving motor (motor), and such a magnet-type motor is mounted on an electric vehicle, a hybrid vehicle, or the like for the purpose of improving fuel efficiency. Is done. The rotor core 1 has a ring shape (annular shape) and is formed by sintering soft magnetic particles. The rotor core 1 and the magnet 2 rotate in a predetermined direction with the center of the rotor core 1 as a rotation axis.
[0014]
As a material constituting the rotor core 1, for example, a nickel-iron alloy is used. Various additives can be added to this.
[0015]
The magnet 2 is composed of a permanent magnet. As this permanent magnet, for example, a neodymium-iron-boron sintered magnet, a ferrite magnet, or a rare earth bonded magnet can be used.
[0016]
Referring to FIG. 2, the rotor core 1 is cylindrical, and a magnet 2 is embedded in a part of the cylinder. The length of the rotor core 1 and the length of the magnet 2 are equal. Therefore, the magnet 2 is provided so as to penetrate the rotor core 1. In the space surrounded by the rotor core 1, a rotating shaft of the electric motor is disposed, and the rotor core 1 and the magnet 2 rotate around the rotating shaft.
[0017]
Next, a method for manufacturing the motor rotor shown in FIGS. 1 and 2 will be described with reference to FIGS. 3 to 8 are sectional views taken along line III-III in FIG. First, with reference to FIG. 3, the 1st member 11, the 2nd member 12, the 3rd member 13, and the 4th member 14 are prepared as a 1st process. The first member 11 and the second member 12 are in contact with each other. A fourth member 14 is fitted in the second member 12. The fourth member 14 can slide in contact with the second member 12. A third member 13 is provided so as to contact the second member 12.
[0018]
Referring to FIG. 4, as the second step, second member 12 is moved in the direction indicated by the arrow. As a result, a space is generated in a region surrounded by the first member 11 and the third member 13. This space is filled with the first powder 21 to be the rotor core. As the first powder 21, for example, nickel-iron powder can be used. The first powder 21 is a space surrounded between the first member 11 and the second member 13 and is disposed so as to surround the fourth member 14.
[0019]
Referring to FIG. 5, the first powder 21 is compressed by the fifth member 15 as the third step. Specifically, the fifth member 15 is kept in contact with the first member 11, the third member 13, and the fourth member 14 without changing the distance between the first member 11 and the third member 13. The first powder 21 is compressed by the member 15. At this time, the fourth member 14 is left in a region surrounded by the first member 11, the second member 12, the third member 13, and the fifth member 15. Thereby, the 1st powder 21 is compressed and the rotor core part 25 is shape | molded. The rotor core portion 25 is a green compact of the first powder 21.
[0020]
With reference to FIG. 6, the fifth member 15 is separated from the rotor core portion 25 as the fourth step. Subsequently, the fourth member 14 is moved in the direction indicated by the arrow. By extracting the fourth member 14 from the rotor core portion 25, a hole 21 h is formed in the rotor core portion 25.
[0021]
Referring to FIG. 7, as the fifth step, the second powder 22 is filled into the hole 21 h of the rotor core portion 25. The second powder 22 is a powder that becomes a permanent magnet, and for example, a neodymium-iron-boron powder can be used. Ferrite powder may also be used.
[0022]
Referring to FIG. 8, as the sixth step, first powder 21 and second powder 22 are compressed using first member 11, second member 12, third member 13, and fifth member 15. . At this time, the heights of the top surfaces of the second member 12 and the fourth member 14 are the same. Thus, by compressing the first powder 21 and the second powder 22, the first powder 21 is brought into contact with the rotor core portion 25, which serves as the rotor core, and the first powder 21. It is possible to obtain a green compact 23 that includes the powder 22 and includes a magnet portion 26 that becomes a magnet.
[0023]
Finally, by sintering the green compact 23 at a temperature of 800 ° C. to 1300 ° C., the electric motor rotor 100 constituted by the rotor core 1 and the magnet 2 shown in FIGS. 1 and 2 can be obtained.
[0024]
According to such a method for manufacturing an electric motor rotor, as shown in FIGS. 3 to 8, the first powder 21 and the second powder 22 are brought into contact with each other and compressed to form the green compact 23. To do. By sintering the green compact 23, the electric motor rotor 100 composed of the rotor core 1 and the magnet 2 can be obtained, and therefore, at the interface between the first powder 21 and the second powder 22, The second powder 22 is sufficiently meshed.
[0025]
That is, in the rotor core portion 25 constituted by the first powder 21 and the magnet portion 26 constituted by the second powder 22, there is no gap at the interface, and the first as the rotor core portion 25 approaches the magnet portion 26. The proportion of the powder 21 decreases and the proportion of the second powder 22 increases. Therefore, since the rotor core and the magnet are firmly coupled, the magnetic resistance in this portion is reduced and a uniform magnetic field can be formed. As a result, the efficiency of the motor can be improved and torque fluctuation can be reduced.
[0026]
In addition, the gap between the rotor core 1 and the magnet 2 can be eliminated without increasing the number of manufacturing steps as compared with a technique in which a metal foil is inserted to improve the adhesion between the rotor core 1 and the magnet 2. it can. Further, in the technology for inserting the metal foil as described above, the thickness of the metal foil, the hole for inserting the magnet of the rotor core, and the size of the magnet thickness are accurately determined in order to eliminate the gap between the rotor core 1 and the magnet 2. It is necessary to manage well. On the other hand, in the present invention, since the metal foil as described above is not inserted, it is not necessary to strictly manage the dimensions, and the manufacture becomes easy.
[0027]
(Embodiment 2)
FIG. 9 is a plan view of an electric motor rotor manufactured by the method according to the second embodiment of the present invention. FIG. 10 is an enlarged plan view showing a portion surrounded by X in FIG. With reference to FIGS. 9 and 10, in motor rotor 100 according to the second embodiment of the present invention, convex portion 1 a and concave portion 1 b are formed on the surface of rotor core 1. A magnet 2 is embedded in a region surrounded by the convex portion 1a and the concave portion 1b.
[0028]
The magnet 2 has a convex part 2 a and a concave part 2 b, and the convex part 1 a of the rotor core 1 fits into the concave part 2 b of the magnet 2. Similarly, the convex part 2 a of the magnet 2 fits into the concave part 1 b of the rotor core 1. In FIG. 10, the shape of the convex portions 1a and 2a and the concave portions 1b and 2b is an arc shape. However, the shape is not limited to this, and the triangular, saw-shaped, and quadrangular convex portions 1a and 2a and the concave portions 1b and 2b are formed. It may be formed.
[0029]
The manufacturing method of the motor rotor 100 shown in FIGS. 9 and 10 makes the shapes of the second and fourth members 12 and 14 shown in FIG. 3 different from those of the first embodiment. That is, a concave portion and a convex portion as shown in FIG. 10 are formed in the fourth member 14. Correspondingly, the concave and convex portions that fit the concave and convex portions of the fourth member 14 are also formed on the surface of the second member 12 that contacts the fourth member 14. 4 and FIG. 5, when the first powder 21 is filled in a predetermined space and the first powder 21 is compressed by the fifth member 15 to form the rotor core portion 25, Convex portions and concave portions are formed on the surface of the rotor core portion 25.
[0030]
When the fourth member 14 is pulled out of the rotor core portion 25 to form the hole 21h, a concave portion and a convex portion are formed on the surface of the hole 21h. By filling the second powder 22 into the hole 21h and then compressing them, the green compact 23 including the magnet part 26 having the convex part and the concave part and the rotor core part 25 can be obtained.
[0031]
Thereafter, if the green compact 23 is sintered, the motor rotor shown in FIGS. 9 and 10 can be manufactured.
[0032]
The electric motor rotor configured as described above according to the second embodiment of the present invention has the same effect as the electric motor rotor according to the first embodiment.
[0033]
Furthermore, since the convex part 1a and the concave part 1b of the rotor core 1 and the concave part 2b and the convex part 2a of the magnet 2 are mutually fitted, the contact area of the outer peripheral part of the magnet 2 and the inner peripheral part of the rotor core 1 increases. For this reason, the contact area between the rotor core portion 25 and the magnet portion 26 when the green compact 23 is molded is increased, and these entanglements are strengthened. As a result, the space between the rotor core portion 25 and the magnet portion 26 can be further reduced.
[0034]
Although the embodiment of the present invention has been described above, the embodiment shown here can be variously modified. First, as the shape of the electric motor rotor 100, the first and second embodiments have shown that the magnet is arranged on the circumference of the cylindrical rotor core, but is not limited thereto. That is, the magnet 2 may be formed to extend radially from the center of the rotor core 1. In this case, the magnet 2 is formed so as to extend in the radial direction of the rotor core 1.
[0035]
Further, the arrangement position of the magnet 2 is arranged in the rotor core 1 in both of the first and second embodiments, but is not limited to this, and the magnet 2 is arranged on the outer periphery of the rotor core 1 and a part of the magnet 2 is arranged. May be exposed to the outside of the rotor core 1.
[0036]
Moreover, you may arrange | position so that the magnet 2 may contact the surface of the rotor core 1. FIG. Further, the magnet 2 may be arranged in a wide area on the rotor core so that the magnet 2 is a pancake type.
[0037]
Further, the surfaces of the magnet 2 and the rotor core 1 may be subjected to various heat treatments such as quenching and annealing. Moreover, you may perform surface treatments, such as plating, on the surface of the rotor core 1 and the magnet 2 as needed.
[0038]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
[0039]
【The invention's effect】
According to the present invention, an electric motor rotor having almost no gap between the rotor core 1 and the magnet 2 can be provided.
[Brief description of the drawings]
FIG. 1 is a plan view of an electric motor rotor manufactured in accordance with Embodiment 1 of the present invention.
2 is a cross-sectional view taken along line II-II in FIG.
3 is a cross-sectional view showing a first step of the method for manufacturing the motor rotor shown in FIGS. 1 and 2. FIG.
4 is a cross-sectional view showing a second step of the method of manufacturing the motor rotor shown in FIGS. 1 and 2. FIG.
5 is a cross-sectional view showing a third step of the method of manufacturing the motor rotor shown in FIGS. 1 and 2. FIG.
6 is a cross-sectional view showing a fourth step of the method for manufacturing the motor rotor shown in FIGS. 1 and 2. FIG.
7 is a cross-sectional view showing a fifth step of the method for manufacturing the motor rotor shown in FIGS. 1 and 2. FIG.
8 is a cross-sectional view showing a sixth step of the method of manufacturing the motor rotor shown in FIGS. 1 and 2. FIG.
FIG. 9 is a plan view of an electric motor rotor manufactured in accordance with Embodiment 2 of the present invention.
10 is an enlarged plan view showing a portion surrounded by X in FIG. 9;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rotor core, 2 magnet, 11 1st member, 12 2nd member, 13 3rd member, 14 4th member, 15 5th member, 21 1st powder, 21h hole, 22 2nd powder, 23 compact , 25 rotor core part, 26 magnet part, 100 motor rotor.

Claims

A method for manufacturing an electric motor rotor comprising a cylindrical rotor core and a magnet having a predetermined shape that is embedded in and contacts the rotor core,
The first powder to be the rotor core and the second powder to be in contact with the first powder and to be the magnet are compressed in a state in which the first powder and the second powder are in contact with each other. A step of preparing a green compact molded by the method, and a step of sintering the green compact,
The step of preparing the green compact includes
A columnar first member having an outer wall defining the inner circumferential shape of the cylindrical rotor core ;
A cylindrical third member having an inner wall defining the outer peripheral shape of the cylindrical rotor core;
An annular member disposed in an annular space between an outer wall portion of the first member and an inner wall portion of the third member, the hole having a hole corresponding to a predetermined shape of the magnet, and the first member A second member that is movable in the annular axial direction in contact with the outer wall of the third member and the inner wall of the third member ;
Has an outer shape corresponding to the hole of the second member, wherein is fitted into the hole, a first step of preparing a fourth member slidable within said bore,
Moving the second member in the axial direction of the ring without moving the fourth member so that the annular space is generated in the region surrounded by the first member and the third member; The annular space is filled with the first powder serving as the rotor core, and the first powder is contained in the annular space surrounded by the first member and the second member. And a second step of surrounding the fourth member that has not been moved ,
A cylindrical fifth member having an outer wall portion having the same shape as the outer peripheral shape of the cylindrical rotor core is prepared, and an upper filling surface of the first powder filled in an annular shape so as to surround the fourth member; The bottom surface of the fifth member is brought into contact with the upper surface of the first member, and the outer wall portion of the fifth member is brought into contact with the inner wall portion of the third member, while the fifth member is formed in a cylindrical shape. The first powder is compressed by moving in the axial direction of the first member and the bottom surface of the fifth member without changing the radial distance between the first member and the third member. The filling upper surface, the upper surface of the first member, and the upper surface of the fourth member are pushed down in the cylindrical axial direction of the fifth member, and the fourth member includes the first member, the second member, leaving a region surrounded by the third member and said fifth member, pressure of said first powder A third step of molding the rotor core and,
The fifth member is removed away from the rotor core, and then the fourth member is moved in the hole of the second member to increase the height of the top surfaces of the second member and the fourth member. A fourth step of pulling out the fourth member from the rotor core and forming a hole corresponding to a predetermined shape of the magnet in the rotor core in the same manner ;
A fifth step of filling the second powder in the holes formed in the rotor core;
The fifth member is prepared again, the bottom surface of the fifth member is brought into contact with the upper surface of the rotor core in which the formed powder is filled with the second powder, and the outer wall portion of the fifth member is While contacting the inner wall portion of the third member, the fifth member is moved in the cylindrical axial direction, and the heights of the top surfaces of the second member and the fourth member are kept the same. A sixth step of compressing the first powder and the second powder to obtain the green compact;
A method for manufacturing an electric motor rotor.

The electric motor rotor according to claim 1, wherein the second step uses nickel-iron powder as the first powder, and the fifth step uses neodymium-iron-boron powder as the second powder. Production method.

In the first step, the step of preparing the green compact includes the fourth member having a concave portion and a convex portion formed on an outer peripheral portion thereof, and the concave portion and the convex portion of the fourth member in contact with the fourth member. The magnet includes the first powder by preparing the second member having a concave portion and a convex portion formed on the inner peripheral portion, and performing the sixth step from the second step. The rotor core having a hole corresponding to the predetermined shape and having a hole formed on the surface of the inner periphery, and the magnet having the shape of the outer periphery including the second powder and fitting to the unevenness; The method for manufacturing an electric motor rotor according to claim 1, wherein the green compact containing the powder is prepared.