永久磁石モータは、回転速度を高くして小形軽量化を図っている。更に小形化を図るため、回転子の磁石にＮｄ−Ｆｅ−Ｂ合金やＳｍ−Ｃｏ合金等の高エネルギー磁石を使用している。一般に、磁石材料は機械的な強度が弱く、高速回転での使用を可能にするために回転子の磁石表面を補強材で補強することが多い。補強材としては、軽量で高強度のカーボン繊維やセラミック繊維が使用されている。
前述の従来技術は、特開平１０−２１０６９０号公報に開示されているように、Ｎｄ−Ｆｅ−Ｂ合金やＳｍ−Ｃｏ合金等の磁石を焼結した後で、回転子の外周や内周にカーボン繊維等を配置するとともに、セラミック繊維やカーボン繊維等を混入した樹脂材で一体に固める方法である。
上記従来技術においては、Ｎｄ−Ｆｅ−Ｂ合金やＳｍ−Ｃｏ合金等の磁石を焼結した後に、補強材としてのカーボン繊維等を樹脂を用いて磁石に貼り付けている。このため、カーボン繊維等が回転子の磁石表面と固定子の間に介在することになり、磁石表面と固定子の間のギャップ長が増加することになる。一方、同じ磁束密度を得るために、磁石の大きさは、ギャップ長に比例して大きくなる。磁石が大きくなると遠心力が大きくなり、補強材も増量する必要がある。そのために従来技術では磁石モータの大幅な小形化が難しかった。
また、従来技術では磁石を一旦焼結しているため、寸法精度が出し難くなる。このため、特開平１０−２１０６９０号公報では、焼結後に外周を研削して精度を確保しているが、加工工程が増えるので高価となる不具合があった。本発明の目的は、このような不具合を解消し、更に小形軽量で生産性の優れた安価な永久磁石モータを提供することである。Permanent magnet motors are designed to be smaller and lighter by increasing the rotational speed. In order to further reduce the size, high-energy magnets such as Nd—Fe—B alloy and Sm—Co alloy are used for the rotor magnet. In general, the magnet material is weak in mechanical strength, and the magnet surface of the rotor is often reinforced with a reinforcing material in order to enable use at high speed. As the reinforcing material, lightweight and high-strength carbon fibers or ceramic fibers are used.
As disclosed in Japanese Patent Application Laid-Open No. 10-210690, the above-described conventional technique is applied to the outer periphery or inner periphery of the rotor after sintering a magnet such as Nd—Fe—B alloy or Sm—Co alloy. This is a method in which carbon fibers and the like are arranged and are integrally hardened with a resin material mixed with ceramic fibers or carbon fibers.
In the above prior art, after sintering a magnet such as Nd—Fe—B alloy or Sm—Co alloy, carbon fiber or the like as a reinforcing material is attached to the magnet using a resin. For this reason, carbon fibers or the like are interposed between the rotor magnet surface and the stator, and the gap length between the magnet surface and the stator increases. On the other hand, in order to obtain the same magnetic flux density, the size of the magnet increases in proportion to the gap length. As the magnet becomes larger, the centrifugal force becomes larger and the amount of reinforcing material needs to be increased. Therefore, it has been difficult for the prior art to significantly reduce the size of the magnet motor.
Further, in the prior art, since the magnet is once sintered, it is difficult to obtain dimensional accuracy. For this reason, in Japanese Patent Application Laid-Open No. 10-210690, accuracy is ensured by grinding the outer periphery after sintering, but there is an inconvenience that it is expensive because the number of processing steps increases. An object of the present invention is to provide an inexpensive permanent magnet motor which eliminates such problems and is small and light and excellent in productivity.
本発明は、複数の電機子巻線を施した固定子と、この固定子の内周に配置した永久磁石を有する回転子を備え、この永久磁石は磁石粉末、たとえば、Ｎｄ−Ｆｅ−Ｂ合金と、補強材、たとえば、カーボンの粒、短線、又はメッシュの混合体とを一括して型に入れてバインダー、たとえば、樹脂で固めたボンド磁石を用いるものである。これにより、ボンド磁石の機械的な強度を確保できるので、磁石の外周に補強材を設けることが不要になる。補強材を除去できれば、永久磁石と固定子のギャップを小さく出来、小形軽量化が可能となる。更に、一括して型に入れ、樹脂で固めるので、寸法精度も確保でき、仕上げの再加工が不要になり、生産性を向上できる。
上記のように磁石粉末と補強材を一体に樹脂で固めるので、生産性が向上し、精度向上ができ、その結果小形で安価な永久磁石モータを実現できる。The present invention includes a stator having a plurality of armature windings and a rotor having a permanent magnet disposed on the inner periphery of the stator, the permanent magnet being magnet powder, for example, an Nd-Fe-B alloy. And a reinforcing material, for example, carbon particles, short wires, or a mixture of meshes, are collectively put into a mold, and a binder magnet, for example, a bonded magnet hardened with a resin is used. Thereby, since the mechanical strength of the bonded magnet can be ensured, it is not necessary to provide a reinforcing material on the outer periphery of the magnet. If the reinforcing material can be removed, the gap between the permanent magnet and the stator can be reduced, and the size and weight can be reduced. Furthermore, since it is put into a mold and hardened with resin, dimensional accuracy can be ensured, finishing rework is not required, and productivity can be improved.
Since the magnet powder and the reinforcing material are integrally hardened with resin as described above, productivity can be improved and accuracy can be improved. As a result, a small and inexpensive permanent magnet motor can be realized.
本発明の永久磁石モータを３相、２極のモータに適用した実施例を図面を用いて説明する。
永久磁石モータの一実施例を示す図１において、固定子２は、固定子ヨーク５に設けられた２４個のスロット６と、それらのスロット６に施された３相の巻線７を備えている。固定子２の内側に回転子１が配置され、回転子１は、ボンド磁石３と磁性体である回転子ヨーク４で構成され、回転軸８に固定されている。ボンド磁石３は、Ｎｄ−Ｆｅ−Ｂ合金等の磁石粉末と、補強材、たとえば、カーボンの粒又は短線の混合体を樹脂で固めたものである。
従来のこの種のモータは、遠心力による回転子１の破壊を回避するために、回転子１の外周を補強材で取り巻いており、回転子１に設けられた磁石の外周と、固定子２の内周とのギャップ、距離が大きくなっていた。しかしながら、本発明のボンド磁石３は、遠心力に対する耐性が大きく、補強材によってその外周を取り巻く必要がない。回転子２の外周は直接ボンド磁石３の表面が露出しているので、ボンド磁石３の外周と固定子２とのギャップ、距離を小さくすることができる。このギャップは、モータの容量によって異なるが約０．４〜０．６ｍｍである。
図２に本発明のボンド磁石３の内部の詳細構造を模式的に示した。ボンド磁石３の内部は、Ｎｄ−Ｆｅ−Ｂ合金の磁石粉末３１の中にカーボンの補強材３２が混在されており、それを樹脂３３で固めている。このように補強材３２を磁石粉末３１内に分布させて配置すると、その強度が格段に強化され、ボンド磁石３の表面に補強材を配置しなくとも十分な強度を保持できる。このため、ボンド磁石３の外周に補強材を巻いて補強する必要がなくなるため、ボンド磁石３の外周と固定子２の内周のギャップを０．４〜０．６ｍｍにすることが可能となった。これにより、小形軽量化と生産性の向上を図ることができる。
本実施例では、磁石粉末３１として、Ｎｄ−Ｆｅ−Ｂ合金の磁石粉末３１を使用したが、Ｓｍ−Ｃｏ磁石やフェライト磁石など永久磁石に属するものであれば何でもよい。また、補強材３２として、本実施例ではカーボンの粒や短線で構成したが、ボンド磁石３の所定の機械強度が確保できるならば、カーボンに限らずガラス、セラミックや金属を用いてもよい。
図３は、本発明の回転子３の他の実施例であり、ボンド磁石３はメッシュ状のカーボン繊維３を外周に配置し、Ｎｄ−Ｆｅ−Ｂ合金の磁石粉末３１と樹脂３３を流し込み一体に固めたボンド磁石３の内部を一部詳しく模式的に示した。ボンド磁石３の内部は図示のように、メッシュ状にしたカーボン等の補強材３２をボンド磁石３の表面に配置し、Ｎｄ−Ｆｅ−Ｂ合金の磁石粉末３１と樹脂３３をそこに流し込んで固めたものである。カーボンの補強材３２のメッシュ内部にも磁石粉末３１が入り込むため、図２の実施例よりも磁石の強度向上を図ることが可能となり、より一層、小形軽量化ができる。
本実施例でも、磁石粉末３１としてＮｄ−Ｆｅ−Ｂ合金の磁石粉末を挙げたが、磁石粉末３１は他にＳｍ−Ｃｏ合金やフェライトなど永久磁石に属するものであれば何でもよい。また、補強材３２としてカーボンの粒や短線で構成したが、ボンド磁石３の所定の機械強度が確保できるならば、カーボンに限らずガラス繊維、セラミック繊維や金属繊維を用いてもよい。
図４は本発明のボンド磁石３を作る場合の装置の一例を示す。この例は磁石粉末３１と補強材３２、樹脂３３を混練して成形型に流し込む方法である。成形型は下型１０と上型１１の２つ割れの型で構成する。作成手順としては、まず成形型に混練した磁石粉末３１と補強材３２、樹脂３３を混合圧力容器１４から注入パイプ１３を通して流し込む。
次に圧力を加えて樹脂を型の隅々まで入り込ませ、樹脂が固まったら下型１０と上型１１を外してボンド磁石３を取り出す。そして、図３の補強材３２のメッシュを使う場合は下型の外周にカーボン等の補強材メッシュ３２を挿入し、上型をかぶせて成形型に混練した磁石粉末３１と樹脂３３を混合圧力容器１４から注入パイプ１３を介して流し込んで固めることによって作成する。
特に磁石粉末３１が異方性の場合は、柔らかいうちにボンド磁石３に磁界を加えた後、固めれば、磁石粉末の方向が揃い、より強い磁石が得られる。その目的で、磁界を発生する磁界発生コイル１５を成形型の両サイドに配置してある。磁石粉末が等方性の場合は、混合体が固まる前でも後でも良い。
図５は本発明のボンド磁石３と回転子ヨーク４、回転軸８を一体に作る場合の装置の一例を示す。図４と同じ記号は同じ動作をする物である。この例も図４と同様に成形型は下型１０と上型１１の２つ割れの型で、下型の中に回転軸８と回転子ヨーク４を図示のように挿入し、上型をかぶせて成形型に混練した磁石粉末３１と補強材３２、樹脂３３を混合圧力容器１４から注入パイプ１３を介して流し込み、圧力を加えて樹脂を型の隅々まで注入し、樹脂が固まったら下型１０と上型１１を外して、ボンド磁石３、回転子ヨーク４および回転軸８が一体化した回転子を取り出す。
また、図３のカーボンやセラミック等の補強材３２のメッシュを使う場合は、下型の外周にカーボンメッシュ３２を挿入し、上型をかぶせて成形型に混練した磁石粉末３１と樹脂３３を混合圧力容器１４から注入パイプ１３を介して流し込んで固める。また、この例でもボンド磁石３に磁界を加えて固めれば、磁石粉末の方向が揃い、より強い磁石が得られるため、磁界を発生する磁界発生コイル１５を成形型の両サイドに配置してある。
以上の例では３相２極、２４スロットの例で示したが相数、極数、スロット数が変わっても同じ効果を得ることが出来ることはいうまでもない。
本発明によれば、小形軽量で生産性の優れた安価な磁石モータを得ることが可能となる。An embodiment in which the permanent magnet motor of the present invention is applied to a three-phase, two-pole motor will be described with reference to the drawings.
In FIG. 1 showing an embodiment of a permanent magnet motor, the stator 2 includes 24 slots 6 provided in the stator yoke 5 and three-phase windings 7 provided in the slots 6. Yes. A rotor 1 is disposed inside the stator 2, and the rotor 1 is composed of a bond magnet 3 and a rotor yoke 4 that is a magnetic body, and is fixed to a rotating shaft 8. The bond magnet 3 is obtained by solidifying a magnet powder such as an Nd—Fe—B alloy and a reinforcing material, for example, a mixture of carbon grains or short wires with a resin.
In this type of conventional motor, in order to avoid the destruction of the rotor 1 due to centrifugal force, the outer periphery of the rotor 1 is surrounded by a reinforcing material, the outer periphery of the magnet provided in the rotor 1, and the stator 2. The gap and the distance from the inner circumference of was increased. However, the bonded magnet 3 of the present invention has high resistance to centrifugal force, and there is no need to surround the outer periphery with a reinforcing material. Since the surface of the bond magnet 3 is directly exposed on the outer periphery of the rotor 2, the gap and distance between the outer periphery of the bond magnet 3 and the stator 2 can be reduced. This gap is approximately 0.4 to 0.6 mm, although it varies depending on the capacity of the motor.
FIG. 2 schematically shows the detailed structure inside the bonded magnet 3 of the present invention. Inside the bonded magnet 3, a carbon reinforcing material 32 is mixed in a magnet powder 31 of an Nd—Fe—B alloy, which is solidified by a resin 33. When the reinforcing material 32 is distributed and arranged in the magnet powder 31 as described above, the strength is remarkably strengthened, and sufficient strength can be maintained without arranging the reinforcing material on the surface of the bond magnet 3. For this reason, since it is not necessary to wrap the reinforcing material around the outer periphery of the bond magnet 3 and reinforce it, the gap between the outer periphery of the bonded magnet 3 and the inner periphery of the stator 2 can be set to 0.4 to 0.6 mm. It was. Thereby, it is possible to reduce the size and weight and improve the productivity.
In this embodiment, the Nd—Fe—B alloy magnet powder 31 is used as the magnet powder 31, but anything may be used as long as it belongs to a permanent magnet such as an Sm—Co magnet or a ferrite magnet. In the present embodiment, the reinforcing material 32 is composed of carbon grains or short wires. However, as long as the predetermined mechanical strength of the bonded magnet 3 can be secured, glass, ceramic, or metal may be used instead of carbon.
FIG. 3 shows another embodiment of the rotor 3 according to the present invention. The bonded magnet 3 has a mesh-like carbon fiber 3 arranged on the outer periphery, and a magnet powder 31 of Nd—Fe—B alloy and a resin 33 are poured and integrated. A part of the interior of the bonded magnet 3 is shown in detail schematically. As shown in the figure, the inside of the bond magnet 3 is provided with a mesh-like reinforcing material 32 such as carbon on the surface of the bond magnet 3, and the Nd—Fe—B alloy magnet powder 31 and the resin 33 are poured into the magnet and hardened. It is a thing. Since the magnet powder 31 also enters the inside of the mesh of the carbon reinforcing material 32, it is possible to improve the strength of the magnet as compared with the embodiment of FIG. 2, and the size and weight can be further reduced.
Also in this embodiment, the magnet powder 31 is an Nd—Fe—B alloy magnet powder, but the magnet powder 31 may be anything other than a permanent magnet such as an Sm—Co alloy or ferrite. Further, although the reinforcing material 32 is composed of carbon grains or short wires, glass fiber, ceramic fiber, or metal fiber may be used instead of carbon as long as the predetermined mechanical strength of the bonded magnet 3 can be ensured.
FIG. 4 shows an example of an apparatus for making the bonded magnet 3 of the present invention. In this example, the magnet powder 31, the reinforcing material 32, and the resin 33 are kneaded and poured into a mold. The mold is composed of a two-part mold of a lower mold 10 and an upper mold 11. As a preparation procedure, first, the magnet powder 31, the reinforcing material 32, and the resin 33 kneaded in the mold are poured from the mixed pressure vessel 14 through the injection pipe 13.
Next, pressure is applied to allow the resin to enter every corner of the mold. When the resin has hardened, the lower mold 10 and the upper mold 11 are removed, and the bonded magnet 3 is taken out. When the mesh of the reinforcing material 32 shown in FIG. 3 is used, a reinforcing material mesh 32 such as carbon is inserted into the outer periphery of the lower mold, and the magnet powder 31 and the resin 33 kneaded in the molding mold with the upper mold covered are mixed pressure vessel It is created by pouring from 14 through an injection pipe 13 and solidifying.
In particular, when the magnet powder 31 is anisotropic, if a magnetic field is applied to the bonded magnet 3 while it is soft and then hardened, the direction of the magnet powder is aligned and a stronger magnet is obtained. For this purpose, magnetic field generating coils 15 for generating a magnetic field are arranged on both sides of the mold. When the magnet powder is isotropic, it may be before or after the mixture is hardened.
FIG. 5 shows an example of an apparatus for making the bonded magnet 3 of the present invention, the rotor yoke 4 and the rotating shaft 8 integrally. The same symbols as those in FIG. 4 indicate the same operations. In this example as well, as shown in FIG. 4, the mold is a split mold of the lower mold 10 and the upper mold 11, and the rotary shaft 8 and the rotor yoke 4 are inserted into the lower mold as shown in the figure, and the upper mold is The magnet powder 31, the reinforcing material 32, and the resin 33, which are covered and kneaded into the mold, are poured from the mixing pressure vessel 14 through the injection pipe 13, and the resin is injected to every corner of the mold by applying pressure. The mold 10 and the upper mold 11 are removed, and the rotor in which the bond magnet 3, the rotor yoke 4 and the rotating shaft 8 are integrated is taken out.
When the mesh of the reinforcing material 32 such as carbon or ceramic shown in FIG. 3 is used, the carbon powder 32 is inserted into the outer periphery of the lower die, and the magnet powder 31 and the resin 33 mixed with the upper die are kneaded with the upper die. It is poured from the pressure vessel 14 through the injection pipe 13 and hardened. Also in this example, if a magnetic field is applied to the bonded magnet 3 and hardened, the direction of the magnet powder is aligned and a stronger magnet can be obtained. Therefore, magnetic field generating coils 15 that generate a magnetic field are arranged on both sides of the mold. is there.
In the above example, the example of three phases, two poles, and 24 slots is shown, but it goes without saying that the same effect can be obtained even if the number of phases, the number of poles, and the number of slots are changed.
According to the present invention, it is possible to obtain an inexpensive magnet motor that is small and light and has excellent productivity.
