Motor

Abstract

To provide a motor capable of preventing reduction in heat dissipation property.SOLUTION: A motor 1 comprises: a rotor core 11 in which a plurality of electromagnetic steel plates 15 are laminated; a plurality of magnet insertion holes 12 disposed at predetermined intervals in a circumferential direction of the rotor core 11; and a magnet 13 inserted into each magnet insertion hole 12 and fixed by a resin mold 14 filling the magnet insertion hole 12. The resin mold 14 consists of a resin and a filler. The filler includes two kinds of a first filler 21 and a second filler 22 having different particle diameters.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an electric motor. [Background technology]

[0002] An example of a conventional motor in this technical field is described in Patent Document 1. The electric motor described in Patent Document 1 includes a rotor core having magnet insertion holes extending in the direction of the rotation axis, magnets inserted into the magnet insertion holes, and a resin mold that fills the space between the magnets and the magnet insertion holes so as to cover the ends of the magnets in the direction of the rotation axis. The rotor core is formed from multiple electromagnetic steel plates stacked along the direction of the rotation axis. A filler such as ceramics is added to the resin mold to improve thermal conductivity and strength. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-139231 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned electric motor, the rotor core is manufactured by punching and laminating electromagnetic steel sheets, which causes unevenness on the inner wall surfaces of the electromagnetic steel sheets surrounding the magnet insertion holes due to the punching process. Furthermore, when the magnets inserted into the magnet insertion holes are filled with a resin mold, if the particle size of the filler contained in the resin mold is larger than the size of the unevenness, the filler will not fill the unevenness sufficiently. If the filler is not filled sufficiently, the contact area between the filler and the electromagnetic steel sheets will be small, which will reduce the heat dissipation performance of the electromagnetic steel sheets.

[0005] The present invention has been made to solve such technical problems, and has an object to provide an electric motor that can prevent a decrease in heat dissipation performance. [Means for solving the problem]

[0006] The electric motor of the present invention comprises a rotor core formed by stacking a plurality of electromagnetic steel plates, a plurality of magnet insertion holes arranged at predetermined intervals along the circumferential direction of the rotor core, and magnets inserted into each magnet insertion hole and fixed by a resin mold filled in the magnet insertion hole, wherein the resin mold is composed of resin and filler, and the filler has a plurality of different particle sizes.

[0007] In the electric motor according to the present invention, the resin mold is composed of resin and filler, and the filler has multiple types of different particle sizes. Therefore, by combining filler with a particle size that fits into the irregularities on the inner wall surface of the electromagnetic steel sheet surrounding the magnet insertion hole and filler with a particle size that fits into the gap between the inner wall surface of the electromagnetic steel sheet surrounding the magnet insertion hole and the magnet, it is possible to increase the heat dissipation paths for the electromagnetic steel sheet and the magnet. As a result, it is possible to prevent a decrease in the heat dissipation performance of the electric motor. [Effects of the Invention]

[0008] According to the present invention, it is possible to prevent a decrease in the heat dissipation performance of the electric motor. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view showing a rotor of an electric motor according to an embodiment. [Figure 2] FIG. 2 is a plan view showing a rotor of the electric motor according to the embodiment. [Figure 3] FIG. 2 is a schematic diagram illustrating two types of fillers having different particle sizes. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of an electric motor according to the present invention will be described with reference to the drawings. The electric motor 1 of this embodiment is used as a drive source for hybrid vehicles or electric vehicles, for example, and is an interior permanent magnet motor (IPM motor) in which magnets (permanent magnets) 13 are embedded inside a rotor core 11. In the case of an IPM motor, reluctance torque can be utilized in addition to magnet torque resulting from the attractive / repulsive forces between the coil and magnet.

[0011] Although not shown, the electric motor 1 mainly comprises an annular stator around which a plurality of coils are wound, a rotor 10 rotatably arranged inside the stator, and a case that houses the stator and rotor 10. The stator and case can be of a known structure, and therefore a description thereof will be omitted here.

[0012] FIG. 1 is a perspective view showing a rotor of an electric motor according to an embodiment, and FIG. 2 is a plan view showing the rotor of an electric motor according to an embodiment. The rotor 10 has a cylindrical rotor core 11 with a central hole. The rotating shaft of the electric motor 1 is fitted into the central hole. The rotor core 11 is formed by laminating a plurality of annular electromagnetic steel sheets 15, each with an axial hole formed in the center, along the direction of the rotation axis L. The axial hole forms the central hole mentioned above. The thickness of each electromagnetic steel sheet 15 is, for example, 0.5 mm or less, but is not limited to this.

[0013] The rotor core 11 is provided with a plurality of magnet insertion holes 12 (16 in this embodiment) that extend along the direction of the rotation axis L so as to penetrate the rotor core 11. As shown in Fig. 2, the 16 magnet insertion holes 12 are arranged at predetermined intervals along the circumferential direction of the rotor core 11. Adjacent magnet insertion holes 12 form a V-shape or an inverted V-shape.

[0014] A magnet 13 is fitted into each magnet insertion hole 12. Magnet 13 is a permanent magnet and has a rectangular parallelepiped shape. Magnet 13 is inserted into magnet insertion hole 12 so that its longitudinal direction is parallel to the direction of rotation axis L, and is fixed to magnet insertion hole 12 by resin mold 14.

[0015] For the magnet 13, neodymium magnets, ferrite magnets, Sm-Co magnets, alnico magnets, etc. are used. Further, the bulk types of magnets mainly include sintered magnets, bonded magnets, etc., but are not limited thereto.

[0016] The resin mold 14 is filled between the inner wall surface of the electromagnetic steel sheet 15 surrounding the magnet insertion hole 12 and the magnet 13 so as to fix the magnet 13 inserted into the magnet insertion hole 12 to the magnet insertion hole 12. That is, the resin mold 14 is configured to surround the magnet 13 inserted into the magnet insertion hole 12.

[0017] The resin mold 14 is composed of a resin and a filler. The resin may be a thermosetting resin or a thermoplastic resin. As the thermosetting resin, epoxy resin, modified epoxy resin typified by vinyl ester resin, phenol resin, melamine resin, urea resin, unsaturated polyester resin, alkyd resin, polyurethane resin, thermosetting polyimide resin, etc. can be used. As the thermoplastic resin, polyether ether ketone, polyphenylene sulfide, polyacrylate ester, polyimide, polyamide, etc. can be used. And from the viewpoint of enhancing the moldability and heat resistance of the resin mold 14, a thermosetting resin is preferable.

[0018] On the other hand, examples of the filler include ceramics such as alumina and zirconia, but are not limited thereto. Note that the material of the filler is preferably non-magnetic and an insulator.

[0019] Also, in the present embodiment, the filler has a plurality of different particle sizes. More specifically, the filler includes those having at least two different particle sizes (the first filler 21 and the second filler 22). As shown in FIG. 3, for example, when the thickness of each electromagnetic steel sheet 15 is d and the maximum distance between the magnet 13 inserted into the magnet insertion hole 12 and the inner wall surface of the electromagnetic steel sheet 15 surrounding the magnet insertion hole 12 is X, the particle size P1 of the first filler 21 satisfies d / 2≦P1≦X, and the particle size P2 of the second filler 22 satisfies P2<d / 2.

[0020] Here, the thickness of the electromagnetic steel sheet 15 refers to the thickness of the electromagnetic steel sheet in the direction of the rotation axis L, and the particle diameters P1 and P2 refer to the diameters when each particle is a perfect sphere.

[0021] When the resin mold 14 containing at least two types of fillers having different particle diameters is filled into the magnet insertion hole 12 to fix the magnet 13, as shown in FIG. 3, since the particle diameter P1 of the first filler 21 satisfies the relationship of d / 2 ≤ P1 ≤ X, it can enter (or in other words, fill) between the magnet 13 inserted into the magnet insertion hole 12 and the inner wall surface of the electromagnetic steel sheet 15 surrounding the magnet insertion hole 12. On the other hand, since the particle diameter P2 of the second filler 22 satisfies the relationship of P2 < d / 2, it can enter the irregularities of the inner wall surface of the electromagnetic steel sheet 15 surrounding the magnet insertion hole 12 (more specifically, the gaps between the inner wall surfaces of the electromagnetic steel sheets 15 adjacent in the direction of the rotation axis L).

[0022] [[ID=II]]

[0023] In this way, the contact points and contact areas between the magnet 13 and the first filler 21, between the first filler 21 and the second filler 22, and between the second filler 22 and the electromagnetic steel sheet 15 can be increased respectively. Therefore, since the heat conduction paths by the first filler 21 and the second filler 22 increase, it becomes possible to improve the heat dissipation performance of the electric motor 1.In the electric motor 1 according to this embodiment, the filler contained in the resin mold 14 has at least two different particle sizes (first filler 21 and second filler 22). Therefore, by combining the first filler 21 having a particle size P1 that fits into the gap between the magnet 13 and the inner wall surface of the electromagnetic steel sheet 15 surrounding the magnet insertion hole 12 and the second filler 22 having a particle size P2 that fits into the unevenness of the inner wall surface of the electromagnetic steel sheet 15 surrounding the magnet insertion hole 12, it is possible to increase the number of heat dissipation paths for the electromagnetic steel sheet 15 and the magnet 13. That is, by setting particle sizes that are optimal for the thermal conductivity of the gap between the magnet 13 and the inner wall surface of the electromagnetic steel sheet 15 surrounding the magnet insertion hole 12, and for the unevenness of the inner wall surface of the electromagnetic steel sheet 15 surrounding the magnet insertion hole 12, it is possible to improve the heat dissipation performance of the electromagnetic steel sheet 15 and the magnet 13. As a result, it is possible to prevent a decrease in the heat dissipation performance of the electric motor 1.

[0024] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various design modifications can be made without departing from the spirit of the present invention as set forth in the claims. [Explanation of symbols]

[0025] 1: electric motor, 10: rotor, 11: rotor core, 12: magnet insertion hole, 13: magnet, 14: resin mold, 21: first filler, 22: second filler, L: rotating shaft

Claims

[Claim 1] a rotor core formed by laminating a plurality of electromagnetic steel sheets; a plurality of magnet insertion holes arranged at predetermined intervals along the circumferential direction of the rotor core; Magnets inserted into the magnet insertion holes and fixed by resin molds filled in the magnet insertion holes; Equipped with the resin mold is composed of a resin and a filler, The electric motor is characterized in that the filler has a plurality of different particle sizes.

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