Interior Permanent Magnet Rotor and Method for Manufacturing the Same

{
  "publication_number": "US2017070111A1",
  "country": "US",
  "kind": "A1",
  "title": "Interior Permanent Magnet Rotor and Method for Manufacturing the Same",
  "abstract": "An interior permanent magnet rotor restrains demagnetization of permanent magnets embedded in a core. Each permanent magnet is formed by joining a first portion and a second portion at a connection. The first and second portions extend from the outer side toward the inner side in the radial direction of the core. The outer end faces of the first and second portions in the radial direction of the core extend in an orientation direction as viewed in section perpendicular to the axial direction. The outside diameter of the core gradually increases from the boundaries between a single magnetic pole and magnetic poles adjoining the single magnetic pole toward the middle of the single magnetic pole in the circumferential direction of the core.",
  "claims": [
    "1. An interior permanent magnet rotor, comprising: a core made of a soft magnetic material; and a permanent magnet embedded in the core, wherein, the permanent magnet includes a first portion and a second portion each extending from an outer side toward an inner side in a radial direction of the core, the first portion and the second portion adjoin each other, the first portion and the second portion form a single magnetic pole, an orientation direction in outer end portions of the first and second portions of the single magnetic pole in the radial direction of the core is such a direction that goes further away from a center of the core toward a middle of the single magnetic pole in a circumferential direction of the core, and outermost end faces of the first and second portions in the radial direction of the core extend in the orientation direction of the permanent magnet as viewed in section perpendicular to an axial direction of the core. 2. The interior permanent magnet rotor according to claim 1, wherein, an outside diameter of the core gradually increases from portions of the core which face the outermost end faces of the first and second portions in the radial direction of the core toward the middle of the single magnetic pole in the circumferential direction of the core. 3. The interior permanent magnet rotor according to claim 2, wherein, the outside diameter of the core gradually increases from boundaries between the single magnetic pole and magnetic poles adjoining the single magnetic pole on both sides toward the middle of the single magnetic pole in the circumferential direction of the core. 4. The interior permanent magnet rotor according to claim 1, wherein, a length of the permanent magnet in the orientation direction is shorter on the inner side in the radial direction of the core than on the outer side in the radial direction of the core. 5. A method for manufacturing the interior permanent magnet rotor according to claim 1, comprising: filling an insertion hole of the core with a magnet material that is a material of the permanent magnet; and orienting/magnetizing by applying a magnetic field to the magnet material in the insertion hole in the radial direction of the core."
  ],
  "description_excerpt": "1. Field of the Invention\n\nThe present invention relates to interior permanent magnet rotors having permanent magnets embedded in a core and methods for manufacturing the same.\n\n2. Description of the Related Art\n\nFor example, United States Patent Application Publication No. 2015/0137629 describes a rotor including permanent magnets extending from the outer side toward the inner side in the radial direction of a core.\n\nIn one possible manufacturing process of this rotor, insertion holes are formed in the core, and a magnetic field is applied from the outside of the core in the radial direction to a material of the permanent magnets (magnet material) filling the insertion holes. In this case, a magnetic path in the magnet material may decrease in the outer ends of the magnet material in the radial direction of the core. If the magnetic path in the magnet material decreases in the outer ends of the magnet material in the radial direction of the core, the permanent magnets have a shorter length in the orientation direction in their outer ends in the radial direction of the core. When an electric motor is driven, the outer parts of the permanent magnets in the radial direction of the core tend to be subjected to a reverse magnetic field opposite to that of the magnetic flux of the permanent magnets. When subjected to the reverse magnetic field, the permanent magnets are more likely to be demagnetized as their length in the orientation direction is shorter.",
  "cpc": [
    "H02K 1/2713",
    "H02K 1/27",
    "H02K 1/2766",
    "H02K 15/03",
    "H02K 2201/03",
    "H02K 29/03"
  ],
  "ipc": [
    "H02K 1/27",
    "H02K 15/03"
  ],
  "assignees": [
    "JTEKT Corp"
  ],
  "inventors": [
    "Naotake Kanda",
    "Yoshiyuki Shibata",
    "Yoshihiro Oono"
  ],
  "filing_date": "2016-08-25",
  "publication_date": "2017-03-09",
  "priority_date": "2015-09-07",
  "application_number": "US-201615247327-A",
  "family_id": "56852194",
  "cited_by_count": 9,
  "citations": [
    "US20040212266A1",
    "US20080224558A1",
    "US20130307365A1",
    "US20150137648A1",
    "US20140225469A1"
  ]
}