JP4528015B2 - Low iron loss internal motor - Google Patents

Description

  The present invention relates to a technique for fixing an iron core of an electric motor, and more particularly to a technique for reducing iron loss of an iron core for an electric motor manufactured by stacking and integrating punched electromagnetic steel sheets.

  In recent years, there has been a demand for improved efficiency of various electric devices from the viewpoint of energy saving. Although the efficiency of electrical equipment is affected by various factors, iron loss, which is a loss generated in the iron core of an electric motor, occupies a relatively large specific gravity. Therefore, recently, electrical steel sheets with less iron loss are used. The case is increasing. As a method of manufacturing a laminated stator and laminated rotor of an inversion motor using such an electromagnetic steel sheet, a steel sheet is punched out, a predetermined number of sheets are laminated as a unit iron core, and bolt tightening, caulking, and welding are used. It is generally fixed.

  Further, the laminated stator is fixed to a case surrounding the stator through a winding coil assembling process. The method of fixing the stator to the case is to use a bolt tightening mold that passes the bolt through the hole that passes through the bolt in the stacking direction to fix the bolt to the case, and an inner diameter that is almost the same as the outer diameter of the stator. A shrink-fitting mold or the like that can be shrink-fitted into a case is generally used. However, in the shrink-fit type, a high compressive stress is generated in the entire stator, and this compressive stress increases iron loss in the electric motor. Also, in bolt fixing, a high compressive stress is locally generated, which also increases the iron loss in the electric motor. {For example, IEEJ rotating machine research material RM-95-27 (January 1995) (non- Patent Document 1)}.

  As described above, one of the causes for increasing the iron loss of the stator of the electric motor is the compressive stress generated in the stator. As shown in FIG. 1, it is generally known that iron loss increases when compressive stress is generated in the direction of magnetic flux (Non-Patent Document 1). In the case of a conventional electric motor, methods for fixing the stator to the case include shrink fitting and fixing with bolts. In shrink fitting, a high circumferential compressive stress is generated in almost the entire yoke portion of the stator. Due to this compressive stress, the iron loss of the electric motor is greatly increased. Even when the bolt is fixed to the case, a high compressive stress is locally generated in the vicinity of the bolt contact position of the stator due to tightening of the bolt. In this way, if a partial high compressive stress region exists in the magnetic path, the flow of magnetic flux is hindered at that portion, and iron loss increases.

  Japanese Unexamined Patent Application Publication No. 2002-136003 (Patent Document 1) is a technique for reducing the adverse effects due to the compressive stress of the stator. This technology is to relieve stress by making a hole in a part of the stator, but this does not sufficiently relieve stress, and it also has a gap in the magnetic path with high magnetic resistance. Conversely, the efficiency of the motor may be reduced.

Electrical Engineering Rotating Machine Research Material RM-95-27 (January 1995) JP 2002-136003 A

Any fixing method generates a compressive stress inside the stator and increases iron loss. By compressing and fixing uniformly in the laminating direction, the compressive stress generated inside the stator is generated throughout, but the magnitude is small. Therefore, the iron loss of the electric motor only increases slightly.
An object of the present invention is to provide an internal rotation type motor that uniformly disperses the compressive stress generated inside the stator for an electric motor at a low level and prevents an increase in iron loss.

In order to solve the above problems, the gist of the present invention is as follows.
In an electric motor having a stator and a rotor that are integrated into a predetermined shape by punching a steel plate and laminating a plurality of sheets, the stator is arranged on the inside, and the stator is arranged on the outside. The flat plate is disposed between the flat plate and the case, and the flat plate is fixed to the case outside the stator by six or more bolts arranged at equal intervals in the circumferential direction . This is a low iron loss inversion motor characterized in that a disc spring is sandwiched therebetween .

  According to the present invention, an effect of reducing iron loss by 5% or more can be obtained as compared with a conventional electric motor in which a stator is directly fixed to a case with a bolt.

  The inventors of the present invention have invented the electric motor described below, considering that the inevitable compressive stress caused by fixing can be uniformly dispersed at a low level so as to be harmless or less affected. As shown in the vertical cross-sectional view shown in FIG. 2 and the horizontal cross-sectional view shown in FIG. 3, the electric motor 9 including the rotor 5 disposed on the inner side, the stator 6 disposed on the outer side, the case 7, and the fixing plate 8. The rotor 5 in which the rotating shaft 17 is inserted is fixed to the case via the bearing 10 (however, it can rotate). Further, the stator 6 is disposed between the fixing flat plate 8 and the case 7 so that the lower surface 11 of the stator 6 around which the winding 16 is wound is in contact with the case, and the upper surface 12 is in contact with the fixing flat plate 8. .

  The fixing flat plate 8 has an annular shape larger than the outer periphery of the stator 6 so that it can be fixed to the case 7 outside the stator 6, and has a plurality of bolt holes 13 on the outer peripheral portion. An annular disc spring 14 is sandwiched between the fixing flat plate 8 and the case 7, and the bolt 15 passes through the bolt hole 13 and the disc spring 14 of the fixing flat plate 8 and is fastened to the case 7. Since the stator upper surface 12 is uniformly pressed by the fixing flat plate 8, a sufficient sum of the pressing forces can be secured even at a low pressure, and the compression stress generated inside the stator 6 can be suppressed to a low level because of the low pressure. In addition, an increase in iron loss can be suppressed.

  The fixing flat plate may be fixed to the case with bolts or the like, or a screw thread may be cut on the outer periphery of the fixing flat plate and the inner periphery of the case contacting the outer periphery of the fixing flat plate, and the fixing flat plate body may be fixed to the case as a screw. Although it is good, in order to suppress an increase in production equipment cost, it is desirable to use bolts that are common to conventional production methods. Further, the number of bolts is preferably 3 or more in order to make the fixing flat plate horizontal, and in order to make the force more uniform, 6 or more bolts are preferably arranged in the circumferential direction.

  Further, as shown in FIG. 4 which is a horizontal sectional view, the flat plate need not be a single plate, and may be composed of a plurality of fixing flat plates 34 that are independent of each other. However, in order to fix the stator to the case more uniformly, as shown in FIGS. 2 and 3, since the fixing flat plate is integral and the outer periphery of the stator is generally circular, it is annular. It is desirable.

  As an example of the present invention, the electric motor shown in FIG. 2 of the above-described embodiment was prepared, and the fixing flat plate was annular and fixed by six bolts equally arranged on the circumference. In the electric motor of the present invention, the iron loss was reduced by 5% as compared with the conventional electric motor in which the stator is directly fixed to the case by the bolt.

It is a figure which shows the residual stress dependence of an iron loss. It is a vertical sectional view of the electric motor of the example of the present invention. It is a horizontal sectional view of the electric motor of the example of the present invention. It is a horizontal sectional view of the electric motor of the example of the present invention.

Explanation of symbols

1 Dependence of iron loss on residual stress at magnetic flux density of 0.7 T 2 Dependence of iron loss on residual stress at magnetic flux density of 1.0 T 3 Dependence of iron loss on residual stress at magnetic flux density of 1.3 T 4 Iron at magnetic flux density of 1.5 T Residual Stress Dependence of Loss 5 Rotor 6 Stator 7 Case 8 Stator Fixing Plate 9 Electric Motor of Example of the Invention 10 Bearing 11 Stator Bottom 12 Stator Top 13 Bolt Hole 14 Disc Spring 15 Bolt 16 Winding 17 Axis of rotation


Patent applicant: Nippon Steel Corporation
Attorney Attorney Shiina and others 1

Claims (1)

In an electric motor having a stator and a rotor that are integrated into a predetermined shape by punching a steel plate and laminating a plurality of sheets, the stator is arranged on the inside, and the stator is arranged on the outside. The flat plate is disposed between the flat plate and the case, and the flat plate is fixed to the case outside the stator by six or more bolts arranged at equal intervals in the circumferential direction . A low iron loss inversion motor characterized in that a disc spring is sandwiched between them .

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