【発明の詳細な説明】[Detailed description of the invention]
発明の技術分野
本発明は開口部が小さいスロツトを等配する回
転電機の鉄心に関する。
発明の技術的背景
一般に開口部が小さいスロツト、すなわち半閉
スロツトを等配する回転電機の鉄心は第１図のよ
うに、鉄心１にスロツト２を等配して配置して中
心線Ａに合致し、スロツト２の溝巾より小さい開
口部３が設けられ、歯部４はスロツト２にはさま
れ、歯頭５は開口部４にはさまれ等配されてい
る。かかる従来の半閉スロツトを有する固定子鉄
心は各スロツト２にコイルを装着して励磁した時
の磁束密度分布を第２図に示す。すなわち歯頭５
に対向する回転子鉄心の表面にホール素子等を取
付けて回転させて磁束密度を検出すると、第２図
のように横軸を位置、縦軸を磁束密度とすると磁
束密度の波形６が得られる。磁束密度は当然では
あるが、開口部３の位置では低く歯頭５の位置で
は高い第１図のスロツト間隔ｔの周期になる。
背景技術の問題点
しかしながら、開口部３毎の磁束密度の脈動
は、結果として開口部３の数に関連した溝高調波
となり、回転電機においては電磁的な騒音を発生
する原因となつている。特にこの溝高調波が関連
して構造物に共振する場合には大きな騒音となる
欠点があつた。
発明の目的
本発明は前記欠点に鑑みなされたもので、溝高
調波を小さくして電磁的な騒音を少なくする回転
電機の鉄心を提供することを目的とする。
発明の概要
すなわち、スロツトの中心に対して開口部の中
心を隣接するスロツトで互に反対にずらすように
形成することによつて、磁束密度の開口部毎の脈
動の周期はずれて２種類の周期で脈動して溝高調
波は低くなる。
発明の実施例
以下本発明を図面に示す一実施例について説明
する。第３図において第１図と同じ作用をする部
分は同一符号としたので説明は省略する。鉄心１
にスロツト２を等配して設け、スロツト２の中心
線Ａに対し開口部３の中心線Ｂは距離e1ずらし、
隣接するスロツト２においては中心線Ａに対し開
口部３の中心線Ｂを反対方向に距離e2ずらして設
けている。更に隣接するスロツト２においても開
口部３の位置を反対方向に距離e1ずらして設け、
以下同じように順次開口部３を配置する。その結
果スロツト２の間隔ｔに対し、開口部３の間隔
t1、t2は2t＝t1＋t2となり、開口部３の間隔は順次
t1、t2、t1、t2……となる。
次に作用を説明する。第３図のスロツト形状に
対し第２図と同様に磁束密度の分布を測定する第
４図のように横軸を位置、縦軸を磁束密度とする
と磁束密度の波形７が得られる。磁束密度は開口
部３の位置にて低く、歯頭５にて高く、開口部３
毎の脈動の周期は開口部３の間隔t1とt2との２種
類が交互にくる形となる。従つて開口部３の数に
関連した溝高調波は第２図と同一成分の溝高調波
は小さくなり、別成分の高調波が新たに生じる。
第１図の溝形状と第３図の溝形状との溝高調波
の磁束密度の大きさを４極、7.5kW、固定子鉄心
のスロツト数48の３相誘導電動機において回転子
鉄心の歯部の表面にホール素子を取付けて検出し
た結果を次表に示す。
TECHNICAL FIELD OF THE INVENTION The present invention relates to an iron core for a rotating electric machine in which slots with small openings are evenly distributed. Technical Background of the Invention In general, the iron core of a rotating electric machine has slots with small openings, that is, semi-closed slots, which are arranged evenly, as shown in Fig. 1, where the slots 2 are arranged evenly on the iron core 1 and aligned with the center line A. Accordingly, an opening 3 smaller than the groove width of the slot 2 is provided, the teeth 4 are sandwiched between the slots 2, and the tooth heads 5 are sandwiched between the openings 4 and are equally spaced. FIG. 2 shows the magnetic flux density distribution of such a conventional stator core having semi-closed slots when a coil is attached to each slot 2 and excited. That is, tooth head 5
When a Hall element or the like is attached to the surface of the rotor core facing the rotor core and rotated to detect the magnetic flux density, as shown in Figure 2, where the horizontal axis is the position and the vertical axis is the magnetic flux density, a waveform 6 of the magnetic flux density is obtained. . Naturally, the magnetic flux density is low at the position of the opening 3 and high at the position of the tooth head 5, at a period corresponding to the slot interval t shown in FIG. Problems with the Background Art However, the pulsations in the magnetic flux density for each opening 3 result in groove harmonics related to the number of openings 3, which causes electromagnetic noise in rotating electric machines. Particularly, when the groove harmonics are related to and resonate with a structure, there is a drawback that a large amount of noise is generated. OBJECTS OF THE INVENTION The present invention was made in view of the above-mentioned drawbacks, and an object of the present invention is to provide an iron core for a rotating electrical machine that reduces groove harmonics and electromagnetic noise. Summary of the Invention In other words, by forming adjacent slots so that the centers of the openings are shifted oppositely from the center of the slot, the period of pulsation of the magnetic flux density for each opening is varied, resulting in two types of periods. pulsates and the groove harmonics become low. Embodiment of the Invention An embodiment of the present invention shown in the drawings will be described below. In FIG. 3, parts having the same functions as those in FIG. 1 are designated by the same reference numerals, and therefore their explanations will be omitted. Iron core 1
The slots 2 are equally spaced, and the center line B of the opening 3 is shifted by a distance e 1 from the center line A of the slot 2.
In the adjacent slot 2, the center line B of the opening 3 is shifted from the center line A by a distance e2 in the opposite direction. Furthermore, in the adjacent slot 2, the position of the opening 3 is shifted in the opposite direction by a distance e 1 ,
Thereafter, the openings 3 are arranged one after another in the same manner. As a result, the distance between the openings 3 and the distance t between the slots 2 is
t 1 and t 2 are 2t = t 1 + t 2 , and the intervals of the openings 3 are sequentially
t 1 , t 2 , t 1 , t 2 .... Next, the action will be explained. For the slot shape shown in FIG. 3, the distribution of magnetic flux density is measured in the same manner as in FIG. 2. If the horizontal axis is the position and the vertical axis is the magnetic flux density as shown in FIG. 4, a waveform 7 of the magnetic flux density is obtained. The magnetic flux density is low at the opening 3 and high at the tooth head 5;
The period of each pulsation is such that two types of intervals t 1 and t 2 of the openings 3 alternate. Therefore, regarding the groove harmonics related to the number of openings 3, the groove harmonics having the same components as those in FIG. 2 become smaller, and harmonics with different components are newly generated. The magnitude of the magnetic flux density of the groove harmonics between the groove shape in Fig. 1 and the groove shape in Fig. 3 is calculated by comparing the magnitude of the magnetic flux density of the groove harmonics between the teeth of the rotor core in a 4-pole, 7.5kW, 3-phase induction motor with 48 slots in the stator core. The following table shows the detection results obtained by attaching a Hall element to the surface of the
【表】
運転条件は固定子に定格電圧を印加し無負荷運
転にて行つた。３相でスロツト数が48の場合、最
も大きい溝高調波は基本波４極の23倍と25倍の極
数を持つものであり、第１図の溝形状に比べ第３
図の溝形状において、この溝高調波が非常に小さ
くなつている。この23倍と25倍の溝高調波が関連
して騒音は小さくなる。
他の実施例として第３図の溝形状を回転子鉄心
に用いても同じ作用が得られる。
発明の効果
以上のように本発明によれば、回転電機の鉄心
においてスロツトの中心に対してスロツトより小
さい巾の開口部の中心を隣接するスロツトで互に
反対方向にずらして形成するようにしたので、溝
高調波の磁束密度を減少して、電磁的な騒音を小
さくでき、また溝高調波が関連した異常トルクを
小さくすることができるなどのすぐれた効果があ
る。[Table] The operating conditions were no-load operation with the rated voltage applied to the stator. In the case of 3 phases and 48 slots, the largest groove harmonics have 23 and 25 times the number of poles of the fundamental wave 4 poles, and compared to the groove shape in Figure 1, the 3rd
In the groove shape shown in the figure, the groove harmonics are extremely small. The noise is reduced due to the groove harmonics of 23 times and 25 times. As another embodiment, the same effect can be obtained by using the groove shape shown in FIG. 3 in the rotor core. Effects of the Invention As described above, according to the present invention, in the iron core of a rotating electrical machine, the centers of the openings having a width smaller than the slot are shifted in opposite directions from the center of the slot in adjacent slots. Therefore, the magnetic flux density of groove harmonics can be reduced, electromagnetic noise can be reduced, and abnormal torque related to groove harmonics can be reduced, which are excellent effects.
【図面の簡単な説明】[Brief explanation of drawings]
第１図は従来の回転電機の鉄心を示す展開図、
第２図は第１図の磁束密度分布図、第３図は本発
明の回転電機の鉄心の一実施例を示す展開図、第
４図は第３図の磁束密度分布図である。
１……鉄心、２……スロツト、３……開口部、
４……歯部、５……歯頭。
Figure 1 is an exploded view showing the iron core of a conventional rotating electrical machine.
2 is a magnetic flux density distribution diagram of FIG. 1, FIG. 3 is a developed view showing an embodiment of the iron core of a rotating electrical machine of the present invention, and FIG. 4 is a magnetic flux density distribution diagram of FIG. 3. 1... iron core, 2... slot, 3... opening,
4...Tooth part, 5...Tooth head.