JP2008118840A - Electric motor stator, electric motor stator manufacturing method, and electric motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stator that suppresses magnetic-flux leakage occurring at a teeth part or a back yoke part of a stator, a stator manufacturing method, and a motor provided with the stator. <P>SOLUTION: A motor stator includes each annular back yoke part and a plurality of teeth parts protruding in a radial direction of each back yoke part. A magnetic shield is provided onto at least either the side face of each teeth part or the side face of each back yoke part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electric motor stator, an electric motor stator manufacturing method, and electric motor technology.

  The electric motor includes a stator and a rotor, and the stator and the rotor interact electromagnetically, thereby rotating the rotor and generating a driving force.

  FIG. 1 is a schematic view of a stator used in an electric motor. As shown in FIG. 1, the stator 1 includes an annular back yoke portion 10 and a plurality of teeth portions 12 protruding in the radial direction of the back yoke portion 10. Each of the plurality of tooth portions 12 includes a coil (not shown) in which windings are concentratedly wound. FIG. 2 is an enlarged schematic view of the stator 1 in the dotted frame x shown in FIG. Generally, the stator 1 includes a stator split core (2a, 2b, 2c,...) Including back yoke split portions (10a, 10b, 10c,...) And teeth portions (12a, 12b, 12c,...). ...) are arranged in an annular shape. As described above, each of the tooth portions 12a, 12b, and 12c has coils (16a, 16b, and 16c) around which windings are concentrated.

  FIG. 3 is a schematic diagram showing the flow of magnetic flux of the stator 1 shown in FIG. As shown in FIG. 3, the rotor 14 constituting the electric motor is disposed on the inner peripheral side of the stator 1, and the rotor 14 is composed of permanent magnets (18a, 18b, 18c) in which N poles and S poles are alternately arranged. , ...). During operation of the electric motor, for example, by passing a current through the coil 16a of the tooth portion 12a, the adjacent permanent magnet 18a in the tooth portion 12a, in the back yoke divided portion 10a, in the back yoke divided portion 10b, in the tooth portion 12b, Magnetic flux flows to the permanent magnet 18c (arrow a shown in FIG. 3). An arrow a shown in FIG. 3 represents an ideal magnetic flux flow when the electric motor is operating. At this time, the electric motor generates a stable torque.

  However, in the case of a motor used for a hybrid vehicle, an electric vehicle, or the like that requires a high output among the electric motors, in addition to the ideal magnetic flux flow (arrow a) shown in FIG. Magnetic flux leakage occurs in which magnetic flux leaks from the back yoke split portion 10a to the outside. When this magnetic flux leakage occurs, the motor torque decreases.

  An example of magnetic flux leakage occurring in the stator 1 will be described below. FIG. 4 is a schematic diagram of the stator 1 shown in FIG. 2, and is a diagram for explaining an example of magnetic flux leakage from a tooth portion to another tooth portion. At the time of operation of a motor that requires high output, as shown by an arrow b in FIG. 4, from the permanent magnet 18a into the tooth portion 12a, the back yoke division portion 10a, the back yoke division portion 10b, and the teeth portion 12b. Although the magnetic flux flows, there is a case where the magnetic flux does not flow into the permanent magnet 18c but flows into the teeth portion 12a (magnetic flux leakage). In particular, in order to prevent the coils (16a, 16b, 16c,...) From being removed from the teeth parts (12a, 12b, 12c,...), The teeth parts (12a, 12b, 12c,...) When the collar (20a, 20b, 20c,...) Is provided in the collar, from the collar to another collar (for example, from the collar 20b of the teeth 12b to the collar 20a of the teeth 12a). ) Is likely to occur. When such a magnetic flux leakage occurs, the magnetic flux emitted from the permanent magnet 18a does not flow to the permanent magnet 18c, that is, a so-called closed circuit state of the magnetic flux, so that the magnetic flux density between the stator and the rotor is reduced and the motor torque is reduced. descend.

  FIG. 5 is a schematic diagram of the stator 1 shown in FIG. 2 and is a view for explaining an example of magnetic flux leakage from the tooth portion to the back yoke portion. As indicated by an arrow c in FIG. 5, the magnetic flux flowing from the permanent magnet 18a into the tooth portion 12a and into the back yoke split portion 10a is transferred from the tooth portion 12a to the outside of the tooth portion 12a, the back yoke split portion 10a (or back). There is a case where it flows into the yoke dividing portion 10b) (magnetic flux leakage). Thus, the magnetic flux flowing from the inside of the tooth portion 12a to the outside of the tooth portion 12a crosses a nearby coil (for example, the coil 16a), and thus once flows into the coil 16a. At this time, the coil 16a generates an eddy current due to the flow of magnetic flux and causes an eddy current loss (iron loss). Due to this eddy current loss, the torque of the motor decreases. Further, the above-described magnetic flux leakage is a typical example, and magnetic flux leakage may occur everywhere in the tooth portion 12 and the back yoke portion 10 shown in FIG. 1 during operation of a motor that requires high output. is there.

  For example, Patent Document 1 proposes a motor that does not leak magnetic flux leaking from the stator to the outside of the motor by providing a leakage flux shield between the stator and the motor frame.

  Further, for example, Patent Document 2 discloses a motor that prevents magnetic flux leaking from the tooth portion of the stator from flowing into the coil by providing a magnetic flux shielding member on the side surface of the coil wound around the tooth portion of the stator. Proposed.

Japanese Utility Model Publication No. 64-47547 JP 2000-341917 A

  However, in the motors of Patent Documents 1 and 2, the magnetic flux leaking from the stator is not leaked to the outside, or the magnetic flux leaking from the teeth portion of the stator is not passed to the coil, but occurs in the teeth portion or back yoke portion of the stator. Magnetic flux leakage cannot be suppressed.

  The present invention is a stator capable of suppressing magnetic flux leakage that occurs in a tooth portion or a back yoke portion of the stator, a method for manufacturing the stator, and an electric motor including the stator.

  The present invention is a stator of an electric motor including an annular back yoke portion and a plurality of teeth portions protruding in a radial direction of the back yoke portion, and includes a side surface of the teeth portion and a side surface of the back yoke portion. At least one of them is provided with a magnetic shield.

  Further, the present invention is a stator of an electric motor including an annular back yoke portion and a plurality of teeth portions protruding in the radial direction of the back yoke portion, and a magnetic flux flowing in the teeth portion when the electric motor is in operation. A magnetic shield is provided on a side surface of the teeth portion that is substantially parallel and a side surface of the back yoke portion that is substantially parallel to the magnetic flux flowing in the back yoke portion.

  In the stator of the electric motor, it is preferable that the magnetic shield is made of flat powder.

  In the stator of the electric motor, the back yoke portion and the teeth portion are made of magnetic powder, and the magnetic shield is made of magnetic powder having a volume average particle size smaller than the volume average particle size of the magnetic powder. It is preferable to be configured.

  Moreover, in the stator of the electric motor, the magnetic powder of the magnetic shield is preferably flat powder.

  In the stator of the electric motor, the volume average particle size of the magnetic powder of the back yoke portion and the tooth portion is in the range of 50 μm to 500 μm, and the volume average particle size of the magnetic powder of the magnetic shield is 10 μm. It is preferable that it is in the range of -50 μm or less.

  Moreover, in the stator of the electric motor, the magnetic powder of the magnetic shield is preferably an Fe—Si based alloy, and the Si content in the Fe—Si based alloy is preferably 1 to 3 wt%.

  The present invention is also a method for manufacturing a stator of an electric motor including an annular back yoke portion and a plurality of tooth portions protruding in a radial direction of the back yoke portion, wherein the side surface of the tooth portion and the back yoke are provided. A magnetic shield is pressure-molded on at least one of the side surfaces of the part.

  Further, the present invention is an electric motor having a stator of an electric motor including an annular back yoke portion and a plurality of teeth portions projecting in a radial direction of the back yoke portion, wherein the stator of the electric motor includes the die portion. A magnetic shield is provided on at least one of the side surface and the side surface of the back yoke portion.

  According to the present invention, by providing a magnetic shield on at least one of the side surface of the tooth portion and the side surface of the back yoke portion, the stator capable of suppressing magnetic flux leakage at the tooth portion or the back yoke portion and the stator. An electric motor provided with can be provided.

  In addition, according to the present invention, magnetic flux leakage at the tooth portion or the back yoke portion can be suppressed by press-molding the magnetic shield on at least one of the side surface of the tooth portion and the side surface of the back yoke portion. A method for manufacturing a stator that can be provided can be provided.

  Embodiments of the present invention will be described below.

  FIG. 6 is a schematic diagram showing an example of the configuration of the stator according to the embodiment of the present invention. As shown in FIG. 6, the stator 3 includes an annular back yoke portion 22, a plurality of teeth portions 24 protruding in the radial direction of the back yoke portion 22, and a magnetic shield (not shown).

  Even if the stator 3 includes a plurality of stator split cores each having a back yoke split portion and a tooth portion arranged in an annular shape, the plurality of teeth portions are arranged in the annular back yoke portion. There is no particular limitation. In the present embodiment, an example in which a plurality of stator split cores are arranged in a ring shape will be described below.

  FIG. 7 is an enlarged schematic view of the stator 3 in the dotted frame y shown in FIG. FIG. 8A is a schematic cross-sectional view of the stator split core 4 taken along line AA shown in FIG. 7, and FIG. 8B is a schematic cross-section of the stator split core 4 taken along line BB shown in FIG. FIG. As shown in FIG. 7 or 8, the stator split core 4 includes a back yoke split portion 22a, a teeth portion 24a, and a magnetic shield 26 (shown in FIG. 8). Further, as shown in FIG. 7, the tooth portion 24a has a coil 32a around which windings are concentrated.

  As shown in FIG. 8, the teeth part 24a is provided with the main-body part 28a and the collar part 30a. The collar portion 30a is for preventing the coil 32a from coming off from the main body portion 28a. In the case where the coil 32a is fixed to the main body portion 28a with resin or the like, the flange portion 32a is not necessarily provided.

  The magnetic shield 26 may be provided on at least one of the side surface of the tooth portion 24a and the side surface of the back yoke dividing portion 22a. The side surface of the tooth portion 24a is a surface (for example, shown in FIGS. 8 (A) and 8 (B)) where the permanent magnet (for example, shown in FIG. 3) of the rotor disposed on the inner peripheral side of the stator 1 and the teeth portion 24a face each other. A side surface other than the arrow I) is pointed out, and the side surface of the back yoke dividing portion 22a indicates a side surface other than the surface in contact with the other back yoke dividing portion (arrow II in FIG. 8A).

  The magnetic shield 26 is not limited to the one provided on the side surface of the tooth portion 24a and the entire side surface of the back yoke divided portion 22a as in the stator divided core 4 of the present embodiment shown in FIG. It may be provided on a part of the side surface of the yoke dividing portion 22a. The side surface of the tooth portion 24a and a part of the side surface of the back yoke dividing portion 22a are, for example, the side surface of the collar portion 30a where the collar portion 30a and the other collar portion face each other (dotted line frame z1 in FIG. 8A). An L-shaped side surface (dotted line frame z2 in FIG. 8A) that switches from the main body portion 28a constituting the teeth portion 24a to the back yoke dividing portion 22a. As described above, the side surface and the L-shaped side surface of the flange portion 30a are typical places where magnetic flux leakage occurs, and at least by providing the magnetic shield 26 on the side surface and L-shaped side surface of the flange portion 30a. The magnetic flux leakage can be prevented, and the reduction in the torque of the electric motor can be reduced.

  9A is a schematic cross-sectional view of a stator split core according to another embodiment taken along line AA shown in FIG. 7, and FIG. 9B is another view taken along line BB shown in FIG. It is a schematic cross section of the stator split core according to the embodiment. Arrows m and n shown in FIGS. 9A and 9B indicate ideal magnetic fluxes flowing in the stator split core 5 when the electric motor is in operation. As described above, among motors that require high output among electric motors, magnetic flux leakage occurs throughout the stator. Therefore, as shown in FIGS. 9A and 9B, the magnetic shield 26 is substantially parallel to the magnetic flux flowing in the side surface of the tooth portion 24a substantially parallel to the magnetic flux flowing in the tooth portion 24a and in the back yoke dividing portion 22a. It is preferable to be provided on the side surface of the back yoke dividing portion 22a. Further, as in the stator split core 4 of the present embodiment shown in FIG. 8, it is more preferable that the magnetic shield 26 is provided on the entire side surface of the teeth portion and the side surface of the back yoke split portion.

  FIG. 10 is a schematic cross-sectional view showing the configuration of the magnetic shield used in this embodiment. As shown in FIG. 10, the magnetic shield 26 is formed to have a predetermined thickness by laminating the long axis (major axis) X of the flat powder 29 in the thickness direction of the magnetic shield 26. Further, the major axis (major axis) X of the flat powder 29 is aligned with the length direction of the magnetic shield 26. Here, the flat powder has a ratio (aspect ratio = X / Y) between the major axis (major axis) X of the flat powder and the minor axis (minor axis) Y of the flat powder shown in FIG. Say. The major axis X of the flat powder and the minor axis Y of the flat powder can be measured with a measuring microscope (Olympus, STM6 type).

  An arrow c shown in FIG. 10 is a magnetic flux. As indicated by an arrow c, the magnetic flux hardly flows in the direction perpendicular to the long axis X of the flat powder 29, that is, in the thickness direction of the magnetic shield 26, and easily flows along the long axis X of the flat powder 29. Therefore, since the magnetic shield 26 becomes a domain wall of the magnetic flux (arrow c) that is about to leak from the stator, magnetic flux leakage can be suppressed.

  As the flat powder 29, for example, pure Fe-based, Fe-Si-based, Fe-Co-based, Fe-Cr-based, Fe-Cr-Ni-based, Fe-Si-Al-based Fe-based metals (alloys), Cu And particles of Al-based metals and Al-based metals.

  Moreover, the aspect ratio of the flat powder 29 may be 1.5 or more, but a range of 6 to 10 is preferable.

  The major axis X (major axis) of the flat powder 29 is preferably in the range of 50 to 1000 μm, and more preferably in the range of 180 to 500 μm. Further, the minor axis Y (minor axis) of the flat powder 29 is preferably in the range of 5 to 500 μm, and more preferably in the range of 30 to 100 μm. If the major axis of the flat powder and the average thickness of the flat powder are outside the above ranges, the strength of the magnetic shield 26 may be reduced.

  The thickness of the magnetic shield 26 is not particularly limited as long as it can prevent magnetic flux leakage from the stator, but is preferably in the range of 5 to 1000 μm.

  The magnetic shield 26 is obtained, for example, by putting flat powder 29 into a mold or the like and press-molding it with a pressure of 700 MPa to 1600 MPa.

  Alternatively, the magnetic shield 26 may be obtained, for example, by mixing the flat powder 29 and an organic binder with a kneader or the like and molding the obtained kneaded material with an injection molding machine or an extrusion molding machine. As the organic binder, thermoplastic resins such as polyamide, polyester, polycarbonate, polyethersulfone and polyethersulfide, and thermosetting resins such as epoxy resin, acrylic resin and urea resin can be used.

  11A is a schematic cross section of the stator split core 4 taken along the lines AA and BB shown in FIG. 7 when the material of the teeth and the back yoke split constituting the stator split core is magnetic powder. FIG. On the other hand, FIG. 11 (b) shows the stator divided core 4 taken along lines AA and BB shown in FIG. 7 when the material of the teeth and the back yoke divided parts constituting the stator divided core is an electromagnetic steel plate. It is a schematic cross section. As shown in FIGS. 11 (a) and 11 (b), the teeth portion 24a and the back yoke divided portion 22a constituting the divided stator core 4 of the present embodiment are obtained by press-molding magnetic powder 38, an electromagnetic steel plate. 33 may be obtained by laminating 33 in the thickness direction of the divided stator core 4 (arrow s shown in FIG. 11 (b)) and integrally molding by adhesion or the like.

  The shape of the magnetic powder 38 is not particularly limited, either spherical or flat. Examples of the magnetic powder 38 include pure Fe-based, Fe-Si-based, Fe-Co-based, Fe-Cr-based, Fe-Cr-Ni-based, and Fe-Si-Al-based metals (alloys). On the other hand, the electromagnetic steel sheet 33 may be a non-oriented electrical steel sheet or a directional electrical steel sheet.

  FIG. 14 is a schematic cross-sectional view showing another example of the configuration of the stator split core 4 along the line AA in FIG. As shown in FIG. 14, the back yoke dividing portion 22a and the teeth portion 24a are formed of a magnetic powder 38a, and the magnetic shield 26 is a magnetic powder having a volume average particle size smaller than the volume average particle size of the magnetic powder 38a. This is a molded body of 38b.

  By using magnetic powder 38b having a volume average particle size smaller than the volume average particle size of magnetic powder 38a used for back yoke dividing portion 22a and teeth portion 24a for magnetic shield 26, the domain wall per unit volume of magnetic shield 26 is used. Therefore, the magnetic flux leakage of the stator can be suppressed.

  In addition, the magnetic powder 38b of the magnetic shield 26 having a volume average particle size smaller than the magnetic powder 38a of the back yoke divided portion 22a and the tooth portion 24a is more preferably flat powder. As described above, if the magnetic shield 26 is a flat powder molded body, magnetic flux hardly flows in the thickness direction of the magnetic shield 26 (for example, as shown in FIG. 10). Therefore, the magnetic shield 26 becomes a domain wall with respect to the magnetic flux that leaks from the back yoke portion 22a and the tooth portion 24a more effectively, and the magnetic flux leakage of the stator can be suppressed.

  Further, by reducing the volume average particle size of the magnetic powder 38b used for the magnetic shield 26 from the volume average particle size of the magnetic powder 38a used for the back yoke split portion 22a and the tooth portion 24a, the eddy current loss of the stator can be reduced. It can also be reduced. If the motor drive frequency is increased to increase the motor rotation speed, the magnetic flux concentrates on the stator surface (that is, the surface of the tooth portion 24a or the back yoke split portion 22a), and eddy current loss increases. FIG. 15 is a diagram showing the relationship between the volume average particle diameter of the magnetic powder constituting the compact and the eddy current loss of the compact. As shown in FIG. 15, if the volume average particle diameter of the magnetic powder constituting the compact is reduced, the eddy current loss of the compact is reduced. Therefore, even if the drive frequency of the motor is increased and the magnetic flux is concentrated on the surface of the stator, the volume average particle size is smaller than the volume average particle size of the magnetic powder 38a used for the back yoke divided portion 22a and the tooth portion 24a. Since the magnetic powder 38b (magnetic shield 26) is on the surface of the stator, eddy current loss of the stator can be reduced. Eddy current loss can be measured with a BH analyzer (SY-8232, manufactured by Iwasaki Tsushinki Co., Ltd.).

  The volume average particle size of the magnetic powder 38a of the back yoke divided portion 22a and the tooth portion 24a is preferably in the range of 50 μm to 500 μm. If the volume average particle size of the magnetic powder 38a of the back yoke divided portion 22a and the teeth portion 24a is outside the above range, the strength of the stator may be reduced, or the iron loss may be significantly deteriorated. The volume average particle size of the magnetic powder 38b of the magnetic shield 26 is preferably in the range of 10 μm to less than 50 μm. When the volume average particle size of the magnetic powder 38b of the magnetic shield 26 is smaller than 10 μm, the hysteresis loss may be significantly deteriorated, and when it is 50 μm or more, the eddy current loss of the stator may be increased. The volume average particle diameter can be measured with a measuring microscope (Olympus, STM6 type), a laser diffraction particle size distribution measuring device, or the like.

  As described above, examples of the magnetic powder 38b of the magnetic shield 26 include pure Fe-based, Fe-Si-based, Fe-Co-based, Fe-Cr-based, etc., which reduce the eddy current loss of the stator. In terms of this, an Fe—Si based alloy is preferable, and an Fe—Si based alloy in which the content of Si in the Fe—Si based alloy is 1 to 3 wt% is more preferable. FIG. 16 is a diagram showing the relationship between the Si content and the eddy current loss of the compact when the magnetic powder of the compact is an Fe—Si alloy. As shown in FIG. 16, the eddy current loss decreases as the Si content in the Fe—Si alloy increases. If the content of Si in the Fe—Si based alloy is more than 3% by weight, the strength of the magnetic shield may be lowered.

  The stator 3 according to the present embodiment is obtained by arranging the stator split core 4 shown in FIG. 7 in an annular shape, and then fixing the outer periphery with a nonmagnetic ring or the like, shrink fitting, and integrating. Further, the stator 3 according to the present embodiment is not limited to the one constituted by the stator split core 4 having the magnetic shield 26. For example, the stator may be a stator in which the stator split core 4 having the magnetic shield 26 and the stator split core not having the magnetic shield (used conventionally) are alternately or randomly arranged.

  Thus, the stator which concerns on this embodiment can suppress magnetic flux leakage by providing a magnetic shield in a teeth part and a back yoke part. Therefore, even when the stator according to the present embodiment is used in a motor that requires high output, it is possible to suppress a decrease in torque of the motor.

  Next, a method for manufacturing the stator according to the present embodiment will be described.

  In the stator manufacturing method according to the present embodiment, a magnetic shield is pressure-molded on at least one of the side surface of the tooth portion and the side surface of the back yoke portion.

  The case where magnetic powder is used for the teeth portion and the back yoke portion constituting the stator according to the present embodiment will be described below as an example.

  FIG. 12 is a diagram for explaining the stator manufacturing method according to the present embodiment. A mold 32 shown in FIG. 12 shows a partial cross section of a mold for forming the stator according to the present embodiment. The mold 32 has a back yoke forming part 34 for forming a back yoke part and a teeth forming part 36 for forming a tooth part.

  As shown in FIG. 12, the magnetic shield is pressure-molded by attaching the magnetic shield 26 described above to the mold 32 by an adhesive or the following method, and then applying the magnetic powder 38 described above to the mold. It is charged and pressed. The pressure for pressure molding is preferably in the range of 700 to 1600 MPa, and more preferably in the range of 1100 to 1600 MPa. Outside the above range, the magnetic shield 26 may not be formed on the side surfaces of the tooth portion and the back yoke portion.

  Further, the pressure molding of the magnetic shield is not necessarily limited to the above. For example, the magnetic shield 26 may be bonded to a pressure-molded product obtained by putting the magnetic powder 38 into the mold 32 and press-molded with an adhesive or the like. Alternatively, the above-described flat powder 29 is attached to the mold 32 by an adhesive or the following method, and after pressure forming and forming a magnetic shield, the magnetic powder 38 is introduced and pressure forming (the pressure is It may be within the above range). Further, or after the flat powder 29 is attached to the mold 32 with an adhesive or the following method, the magnetic powder 38 is charged and pressure-molded (the pressure is in the above range). Good.

  As a method of attaching the flat powder 29 or the magnetic shield 26 to the mold 32, the flat powder 29 or the magnetic shield 26 may be attached to the mold 32 by generating static electricity in the mold 32. By generating static electricity in the mold 32, it is possible to prevent the flat powder 29 or the magnetic shield 26 from being peeled off from the mold 32 before pressure molding.

  Alternatively, the flat powder 29 or the magnetic shield 26 may be attached to the mold 32 by applying a magnetic field to the mold 32. By applying a magnetic field to the mold 32, it is possible to prevent the flat powder 29 or the magnetic shield 26 from being peeled off from the mold 32 before pressure molding.

  Alternatively, the flat powder 29 and the binder resin described above may be mixed and the kneaded material may be applied to the mold 32. Since the kneaded product is viscous, it is possible to suppress the flat powder 29 from being peeled off from the mold 32 before pressure molding by surface tension.

  In addition, it is preferable to apply a lubricant such as mineral oil, synthetic oil, or grease to the mold 32 before the flat powder 29 or the magnetic shield 26 is attached to the mold 32. By applying the lubricant, the stator according to the present embodiment after pressure molding can be easily peeled off from the mold 32.

  Next, the case where an electromagnetic steel plate is used for the teeth portion and the back yoke portion constituting the stator according to the present embodiment will be described below as an example.

  In the case of using an electromagnetic steel sheet, the magnetic shield is pressure-formed by attaching the magnetic shield to an integrated stator by laminating a plurality of electromagnetic steel sheets punched by a pressing device or the like with an adhesive or the like.

  As described above, in the stator manufacturing method according to the present embodiment, it is possible to manufacture a stator in which magnetic flux leakage is suppressed by providing the magnetic shields on the back yoke portion and the tooth portion constituting the stator.

  Next, an electric motor including the stator according to the present embodiment will be described.

  FIG. 13 is a schematic diagram illustrating an example of the configuration of the electric motor according to the present embodiment. The electric motor is not particularly limited, such as a pulse motor such as an AC motor, an SR motor, or a claw pole type motor. In the present embodiment, an SR motor (hereinafter simply referred to as a motor) will be described as an example. As shown in FIG. 13, the motor 6 includes a stator 40, a rotor 42, a frame (not shown) that accommodates the stator 40 and the rotor 42. The stator 40 has the same configuration as the above-described stator (for example, the stator 3 shown in FIG. 6), and at least one of the side surfaces of the tooth portions (50a, 50b,...) And the back yoke portion 52. And a magnetic shield (not shown). The stator 40 is fixed inside the frame.

  The rotor 42 includes a shaft 44 and a rotor core 46. As shown in FIG. 13, the rotor 42 has a rotor core 46 fixed around a shaft 44 disposed in the center. Further, the rotor 42 is inserted and arranged so as to have a predetermined gap between the rotor 42 and the stator 40.

  The rotor core 46 is provided with a plurality of permanent magnets (48a, 48b,...). Further, the rotor core 46 is configured by laminating and integrating a plurality of the above-described electromagnetic steel plates punched by a pressing device. The configuration of the rotor core 46 is not limited to this, and the rotor core 46 may be formed by putting the magnetic powder into a mold and press-molding it. The shaft 44 is supported on the frame body via a bearing (not shown).

  Next, the operation of the motor 6 according to this embodiment will be described. For example, when a current is passed through a coil (not shown) of the teeth portion 50a of the stator 40, a magnetic flux flows from the permanent magnet 48a into the teeth portion 50a, and the permanent magnet 48a is attracted to the teeth portion 50a. Furthermore, by passing a current through a coil (not shown) of another tooth portion 50b, another permanent magnet 48b is attracted to the tooth portion 50b. By continuously performing this, the rotor 42 rotates and torque is generated.

  The magnetic flux generated from the permanent magnet 48a flows through the tooth portion 50a to the back yoke portion 52. However, when the magnetic flux leaks from the teeth portion 50a and the back yoke portion 52, the force that attracts the permanent magnet 48a becomes weak, and the torque decreases. Since the motor 6 according to this embodiment includes magnetic shields on the side surfaces of the teeth portions (50a, 50b,...) And the back yoke portion 52, the teeth portions (50a, 50b,...) And the back yoke. Magnetic flux leakage from the part 52 can be suppressed.

  As described above, the motor according to the present embodiment has been described with reference to FIG. 13. However, the configuration of the motor is not limited to this, and may be, for example, an embedded motor in which a permanent magnet is embedded in a rotor core. Even if there are design changes within a range not departing from the gist of the present invention, they are included in the present invention.

It is a schematic diagram of the stator used for an electric motor. It is an expansion schematic diagram of the stator 1 in the dotted-line frame x shown in FIG. It is a schematic diagram which shows the flow of the magnetic flux of the stator 1 shown in FIG. It is a schematic diagram of the stator 1 shown in FIG. 2, Comprising: It is a figure for demonstrating an example of the magnetic flux leakage from a teeth part to another teeth part. It is a schematic diagram of the stator 1 shown in FIG. 2, Comprising: It is a figure for demonstrating an example of the magnetic flux leakage from a teeth part to a back yoke part. It is a schematic diagram which shows an example of a structure of the stator which concerns on embodiment of this invention. It is an expansion schematic diagram of the stator 3 in the dotted-line frame y shown in FIG. It is a schematic cross section of the stator split core 4 shown in FIG. FIG. 8 is a schematic cross-sectional view of a stator split core according to another embodiment shown in FIG. 7. It is a schematic cross section which shows the structure of the magnetic shield used for this embodiment. FIG. 8 is a schematic cross-sectional view of the stator split core 4 taken along the lines AA and BB shown in FIG. 7 when the materials of the teeth and the back yoke split constituting the stator split core are magnetic powder and an electromagnetic steel plate. It is a figure for demonstrating the manufacturing method of the stator which concerns on this embodiment. It is a schematic diagram which shows an example of a structure of the electric motor which concerns on this embodiment. It is a schematic cross section which shows another example of a structure of the stator division | segmentation core 4 in the AA of FIG. It is a figure which shows the relationship between the volume average particle diameter of the magnetic powder which comprises a molded object, and the eddy current loss of a molded object. It is a figure which shows the relationship between Si content and eddy current loss of a molded object in case the magnetic powder of a molded object is a Fe-Si type alloy.

Explanation of symbols

  1, 3, 40 Stator, 2a, 2b, 2c, 4, 5 Stator split core, 6 Motor, 10, 22, 52 Back yoke part, 10a, 10b, 10c, 22a Back yoke split part, 12, 12a, 12b, 12c, 24, 24a, 50a, 50b Teeth part, 14, 42 Rotor, 16a, 16b, 16c, 32a Coil, 18a, 18b, 18c Permanent magnet, 20a, 20b, 20c, 30a collar part, 26 Magnetic shield, 28a Body Part, 29 flat powder, 32 mold, 33 electromagnetic steel plate, 34 back yoke forming part, 36 teeth forming part, 38, 38a, 38b magnetic powder, 44 shaft, 46 rotor core, 48a, 48b permanent magnet.

Claims (9)

A stator of an electric motor including an annular back yoke portion and a plurality of teeth portions protruding in a radial direction of the back yoke portion,
A stator for an electric motor comprising a magnetic shield on at least one of a side surface of the teeth portion and a side surface of the back yoke portion. A stator of an electric motor including an annular back yoke portion and a plurality of teeth portions protruding in a radial direction of the back yoke portion,
An electric motor comprising a magnetic shield on a side surface of the tooth portion substantially parallel to the magnetic flux flowing in the tooth portion and a side surface of the back yoke portion substantially parallel to the magnetic flux flowing in the back yoke portion during operation of the electric motor. Stator.   The stator of an electric motor according to claim 1 or 2, wherein the magnetic shield is made of flat powder.   3. The stator of the electric motor according to claim 1, wherein the back yoke portion and the teeth portion are made of magnetic powder, and the magnetic shield is a volume average particle smaller than a volume average particle size of the magnetic powder. A stator for an electric motor, characterized by comprising magnetic powder having a diameter.   The stator of an electric motor according to claim 4, wherein the magnetic powder of the magnetic shield is a flat powder.   The stator of the electric motor according to claim 4 or 5, wherein the volume average particle size of the magnetic powder of the back yoke part and the tooth part is in the range of 50 µm to 500 µm, and the volume of the magnetic powder of the magnetic shield. An average particle size is in a range of 10 μm or more to less than 50 μm.   It is a stator of the electric motor of any one of Claims 4-6, Comprising: The magnetic powder of the said magnetic shield is a Fe-Si type alloy, and content of Si in the said Fe-Si type alloy is 1 A stator for an electric motor, which is ˜3% by weight. A method for manufacturing a stator of an electric motor, comprising: an annular back yoke portion; and a plurality of teeth portions protruding in a radial direction of the back yoke portion,
A method of manufacturing a stator for an electric motor, comprising: forming a magnetic shield on at least one of a side surface of the teeth portion and a side surface of the back yoke portion. An electric motor having a stator of an electric motor including an annular back yoke portion and a plurality of teeth portions protruding in a radial direction of the back yoke portion,
The electric motor includes a stator having a magnetic shield on at least one of a side surface of the die portion and a side surface of the back yoke portion.