Patents by Inventor Masahiro Nigo

Masahiro Nigo has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 10008893
    Abstract: In an interior permanent magnet motor, each of permanent magnets has a radially-inner magnet contour surface, a radially-outer magnet contour surface, and a pair of side-end magnet contour surfaces. Each of magnet insertion holes has a radially-inner insertion hole contour surface, a radially-outer insertion hole contour surface, and a pair of side-end insertion hole contour surfaces. The radially-outer magnet contour surface and the radially-outer insertion hole contour surface are each formed by a first arc surface. The radially-inner magnet contour surface and the radially-inner insertion hole contour surface are each formed by a second arc surface and at least one straight surface configured to suppress movement of the permanent magnet along the magnet insertion hole having an arc shape.
    Type: Grant
    Filed: August 26, 2014
    Date of Patent: June 26, 2018
    Assignee: Mitsubishi Electric Corporation
    Inventors: Masahiro Nigo, Kazuchika Tsuchida, Kazuhiko Baba
  • Patent number: 9929610
    Abstract: A permanent magnet embedded electric motor includes a slit and a flux barrier. A hole defining portion of a magnet insertion hole includes an extended portion. The extended portion projects toward an interpolar core portion in a rotor core in an area positioned further on an outer side of a circumferential direction with respect to a width-direction end surface of a permanent magnet. (Lb) is larger than (La), and (Lc) is smaller than (Ld), where the (La) represents a distance between the slit and the core outer peripheral surface; the (Lb) represents a distance between the slit and an outer peripheral-side surface of the permanent magnet; the (Lc) represents a shortest distance between the extended portion and the interpolar core portion; and the (Ld) represents a thickness of the permanent magnet.
    Type: Grant
    Filed: October 29, 2013
    Date of Patent: March 27, 2018
    Assignee: Mitsubishi Electric Corporation
    Inventors: Masahiro Nigo, Naohiro Oketani, Koji Yabe, Kazuhiko Baba
  • Publication number: 20180062462
    Abstract: A rotor of a permanent-magnet-embedded electric motor includes an annular rotor core having a plurality of magnet insertion holes formed in a circumferential direction, and permanent magnets inserted into the magnet insertion holes, respectively. The rotor core is formed by alternately stacking a first core block and a second core block in an axial direction of the rotor core, the first core block not having slits between each of the magnet insertion holes and a circumferential surface of the rotor core, and the second core block having the slits between each of the magnet insertion holes and the circumferential surface of the rotor core. One of the slits and one end of the permanent magnet are arrayed in a radial direction, and the other slit and the other end of the permanent magnet are arrayed in the radial direction.
    Type: Application
    Filed: June 15, 2015
    Publication date: March 1, 2018
    Inventors: Atsushi ISHIKAWA, Masahiro NIGO
  • Patent number: 9899897
    Abstract: A permanent magnet buried type electric motor includes a rotator having a rotator core and a stator. The rotator core includes: a plurality of magnet accommodating holes formed as many as the number of poles; a plurality of permanent magnets; air holes through which a coolant and a refrigerant oil pass; and a fastening hole. The magnet accommodating hole is formed into a shape that projects toward a radially inner side and is recessed toward a radially outer side. The air hole portions and the fastening holes are arranged so as to be alternately positioned. The air hole portion is formed into such a shape that includes a portion extending in an arc shape along an outer peripheral surface of a rotary shaft in a circumferential direction of the rotator core so that an area of the air hole portion is larger than an area of the fastening hole.
    Type: Grant
    Filed: December 21, 2012
    Date of Patent: February 20, 2018
    Assignee: Mitsubishi Electric Corporation
    Inventors: Kazuhiko Baba, Masahiro Nigo, Kazuchika Tsuchida
  • Patent number: 9876402
    Abstract: An interior permanent magnet motor includes a stator and a rotor. The rotor includes a rotor core formed by laminating a plurality of plate members. The rotor core has a plurality of magnet insertion holes formed therein, into which corresponding permanent magnets are respectively inserted. At least one slit and at least one caulked portion are formed between a rotor outer peripheral surface of the rotor and a radially-outer insertion hole contour surface of the magnet insertion hole. At least a part of the caulked portion is positioned between a pair of width extended lines of the slit.
    Type: Grant
    Filed: September 18, 2014
    Date of Patent: January 23, 2018
    Assignee: Mitsubishi Electric Corporation
    Inventors: Kazuchika Tsuchida, Masahiro Nigo, Kazuhiko Baba, Atsushi Ishikawa, Tomoaki Oikawa
  • Patent number: 9853510
    Abstract: An interior permanent magnet motor includes a stator and a rotor rotatably arranged so as to be opposed to the stator. The rotor includes a rotor core having a plurality of magnet insertion holes formed therein, into which corresponding permanent magnets are respectively inserted. The plurality of permanent magnets and the plurality of magnet insertion holes are each formed into an arc shape that is convex toward a center side of the rotor. When a shortest distance between the adjacent magnet insertion holes is defined as an inter-pole shortest distance (L), a ratio of the inter-pole shortest distance (L) to an outer diameter (D) of the rotor is 0.035?L/D?0.045.
    Type: Grant
    Filed: December 19, 2014
    Date of Patent: December 26, 2017
    Assignee: Mitsubishi Electric Corporation
    Inventors: Atsushi Ishikawa, Kazuhiko Baba, Masahiro Nigo, Kazuchika Tsuchida
  • Patent number: 9800105
    Abstract: A rotor core includes a plurality of first electromagnetic steel plates that are stacked in an axial direction and a plurality of second electromagnetic steel plates that are stacked in an axial direction at both ends of the electromagnetic steel plate group thereof. The first electromagnetic steel plates are provided therein with magnet insertion holes and first flux barriers. The second electromagnetic steel plates are provided therein with the magnet insertion holes, second flux barriers, and projections that regulate the positions of the magnets. The second electromagnetic steel plates are stacked at at least one of the axial direction ends of the electromagnetic steel plate group including the plurality of first electromagnetic steel plates and are provided at a position overhanging the axial direction end of a stator core.
    Type: Grant
    Filed: November 1, 2012
    Date of Patent: October 24, 2017
    Assignee: Mitsubishi Electric Corporation
    Inventors: Masahiro Nigo, Naohiro Oketani, Koji Yabe, Kazuhiko Baba
  • Publication number: 20170294814
    Abstract: In a permanent magnet embedded electric motor, a rotor iron core of a rotor disposed on an inner diameter side of a stator includes: a plurality of first slits that are formed on a radial direction outer side of a magnet insertion hole, and communicate with the magnet insertion hole; a plurality of second slits formed at positions opposed to and spaced apart from the first slits; inter-slit iron core portions formed between the first slits and the second slits; outer side iron core portions formed between the second slits and an outer circumferential surface of the rotor iron core; space portions communicating with rotating direction end portions of the magnet insertion hole; and thin iron core portions that are formed between the space portions and the outer circumferential surface of the rotor iron core, and extend in a rotating direction.
    Type: Application
    Filed: October 7, 2014
    Publication date: October 12, 2017
    Inventors: Kazuhiko BABA, Masahiro NIGO, Atsushi ISHIKAWA
  • Patent number: 9762096
    Abstract: An interior permanent magnet motor includes: a rotor; a stator; and a plurality of permanent magnets respectively inserted into a plurality of magnet insertion holes formed in a rotor core, the rotor core being formed by laminating a plurality of magnetic steel sheets, the magnetic steel sheets including first magnetic steel sheets each not having a magnet stopper in the magnet insertion hole, and second magnetic steel sheets each having magnet stoppers at both end portions of the magnet insertion hole, the rotor core including a laminate of the magnetic steel sheets in a lamination mode in which, when Hn represents a distance between an upper end surface of the second magnetic steel sheet and an upper end surface of the n-th second magnetic steel sheet, a progression of differences of Hn is a geometric progression.
    Type: Grant
    Filed: February 20, 2013
    Date of Patent: September 12, 2017
    Assignee: Mitsubishi Electric Corporation
    Inventors: Naohiro Oketani, Masahiro Nigo, Kazuhiko Baba, Koji Yabe
  • Patent number: 9762098
    Abstract: A rotor of an interior permanent magnet motor includes a rotor core having a plurality of magnet insertion holes, a shaft, a plurality of rare-earth magnets, and a pair of magnet fixing members. One surface of the magnet fixing member is provided with a plurality of pairs of tongue-like portions, and the tongue-like portions are inserted into the magnet insertion holes. On each of both sides in a rotary shaft direction, the rare-earth magnets have both end surfaces in a rotor circumferential direction sandwiched by a corresponding pair of tongue-like portions. An interval between the tongue-like portions includes, at a position separated from a base position, an interval that is smaller than the width of the rare-earth magnet in the rotor circumferential direction.
    Type: Grant
    Filed: October 2, 2013
    Date of Patent: September 12, 2017
    Assignee: Mitsubishi Electric Corporation
    Inventors: Naohiro Oketani, Masahiro Nigo, Kazuhiko Baba, Koji Yabe
  • Patent number: 9647501
    Abstract: A rotor outer peripheral surface includes first arcs and second arcs. The first arc is positioned in a magnetic pole center portion. The second arc is positioned in an inter-pole portion. The first arc bulges toward a radially outer side to a higher degree than the second arc. An air gap is varied in a manner of being increased as approaching from each of the magnetic pole center portions to the adjacent inter-pole portions. A hole defining portion of a magnet insertion hole on the radially outer side has a curvature of a third arc, and a hole defining portion of the magnet insertion hole on a radially inner side has a curvature of a fourth arc. An opening angle of a tooth tip portion, an opening angle of the first arc, and an opening angle of the third arc coincide with each other.
    Type: Grant
    Filed: February 14, 2013
    Date of Patent: May 9, 2017
    Assignee: Mitsubishi Electric Corporation
    Inventors: Masahiro Nigo, Kazuhiko Baba, Kazuchika Tsuchida
  • Patent number: 9634531
    Abstract: In an interior permanent magnet motor, at least one magnetic pole center slit and a plurality of side slits are formed between a rotor outer peripheral surface of a rotor and a radially-outer insertion hole contour surface of a magnet insertion hole. The plurality of side slits are formed so that at least one side slit is formed on each of both sides of the magnetic pole center slit in a width direction. The area of the magnetic pole center slit is smaller than the area of each of the plurality of side slits. A width of each of the plurality of side slits is larger than an interval between the adjacent slits.
    Type: Grant
    Filed: September 25, 2013
    Date of Patent: April 25, 2017
    Assignee: Mitsubishi Electric Corporation
    Inventors: Kazuhiko Baba, Masahiro Nigo, Kazuchika Tsuchida, Atsushi Ishikawa
  • Publication number: 20170110944
    Abstract: In an interior permanent magnet motor, a magnet insertion hole of a rotor core is curved into an arc shape, and a convex portion side of the arc shape is arranged on a center side of a rotor. The magnet insertion hole has a first line, a second line, and a pair of third lines. The first line is located on the radially outer side of the second line. Each of the third lines connects the first line and the second line to each other. The first line includes an arc portion and a pair of concave portions. Each of the concave portions is located at an end of the arc portion of the first line.
    Type: Application
    Filed: April 16, 2015
    Publication date: April 20, 2017
    Applicant: Mitsubishi Electric Corporation
    Inventors: Masahiro NIGO, Kazuhiko BABA, Kazuchika TSUCHIDA
  • Publication number: 20170098970
    Abstract: An end of each of slits of a rotor on a magnet insertion hole side has a triangular shape. A slit inner-side line of each of the slits includes an apex and a pair of side ends. An interval between each of the pair of side ends and the magnet insertion hole is larger than an interval between the apex and the magnet insertion hole, and an interval between the apex and the magnet insertion hole is larger than a plate thickness of each of steel plates forming a rotor core.
    Type: Application
    Filed: April 28, 2014
    Publication date: April 6, 2017
    Inventors: Kazuchika TSUCHIDA, Tomoaki OIKAWA, Masahiro NIGO, Naohiro OKETANI
  • Publication number: 20170070109
    Abstract: Provided is an interior permanent magnet motor, including: a rotor including a plurality of permanent magnets; and a stator. The rotor further includes a rotor core. The rotor core has a plurality of magnet insertion holes. A plurality of slits are formed in a region of the rotor core, which is located on a radially outer side of the magnet insertion holes. At least two of the slits are formed so that a core region sandwiched between the two slits has a portion increased toward the radially outer side.
    Type: Application
    Filed: April 22, 2014
    Publication date: March 9, 2017
    Inventors: Masahiro NIGO, Kazuchika TSUCHIDA
  • Publication number: 20170070112
    Abstract: Provided is an interior permanent magnet motor, including: a stator; and a rotor, in which an outline of each of magnet insertion holes includes a radially inner-side line, a radially outer-side line, a pair of side lines, a pair of first round portions, and a pair of second round portions, in which a thin portion is formed between an outer peripheral surface of the rotor and each of the side lines, in which each of the first round portions is provided between a corresponding end of the corresponding radially outer-side line and a corresponding end of the corresponding side line, and in which each of the second round portions is provided between a corresponding end of the corresponding radially inner-side line and a corresponding end of the corresponding side line.
    Type: Application
    Filed: July 1, 2014
    Publication date: March 9, 2017
    Inventors: Atsushi ISHIKAWA, Kazuhiko BABA, Masahiro NIGO, Kazuchika TSUCHIDA
  • Patent number: 9577483
    Abstract: A rotor includes a plurality of magnets, and an annular rotor core having a plurality of magnet insertion holes formed in a circumferential direction, into which the magnets are respectively inserted, in which each of the magnet insertion holes is formed with a protruding portion A on an inner wall surface on an inner diameter side in a radial direction of the rotor, and each of the magnets is formed with a recessed portion that is fitted to the protruding portion A when the magnet is inserted into the magnet insertion holes. With this configuration, fixation of the magnets is facilitated, and generation of chipping and vibration noise due to a movement of the magnets at the time of activation or rotation can be suppressed, thereby enabling to provide the rotor having high quality and high reliability.
    Type: Grant
    Filed: April 6, 2012
    Date of Patent: February 21, 2017
    Assignee: Mitsubishi Electric Corporation
    Inventors: Kazuchika Tsuchida, Masahiro Nigo
  • Patent number: 9472986
    Abstract: A rotor includes a rotor iron core in which magnet insertion holes that are arrayed in a radial direction so as to be convex toward an inner peripheral side are provided for each magnetic pole, and in which the magnet insertion holes are arranged in a circumferential direction according to the number of magnetic poles, and flat-shaped permanent magnets that are inserted respectively in the magnet insertion holes, wherein the magnet insertion holes, which are arranged on an innermost peripheral side and adjacent to each other in a circumferential direction are provided in such a manner that the width of the magnet insertion hole gradually becomes larger toward the inner peripheral side such that the width of the iron core between the adjacent magnet insertion holes in a circumferential direction is constant in a radial direction.
    Type: Grant
    Filed: December 26, 2011
    Date of Patent: October 18, 2016
    Assignee: Mitsubishi Electric Corporation
    Inventors: Kazuchika Tsuchida, Masahiro Nigo
  • Publication number: 20160276886
    Abstract: An interior permanent magnet motor includes a stator and a rotor. The rotor includes a rotor core having a plurality of magnet receiving holes, and a plurality of permanent magnets are received in each of the magnet receiving holes. A plurality of slits are formed at a part between an outer peripheral surface of the rotor and an outer-side defining line of the each of the magnet receiving holes. At least one space portion is secured between the plurality of permanent magnets, and the space portion is opposed to any one of the plurality of slits in a direction parallel to a magnetic pole center line.
    Type: Application
    Filed: December 5, 2013
    Publication date: September 22, 2016
    Inventors: Kazuhiko BABA, Masahiro NIGO, Kazuchika TSUCHIDA, Atsushi ISHIKAWA
  • Publication number: 20160261154
    Abstract: An interior permanent magnet motor includes a stator and a rotor rotatably arranged so as to be opposed to the stator. The rotor includes a rotor core having a plurality of magnet insertion holes formed therein, into which corresponding permanent magnets are respectively inserted. The plurality of permanent magnets and the plurality of magnet insertion holes are each formed into an arc shape that is convex toward a center side of the rotor. When a shortest distance between the adjacent magnet insertion holes is defined as an inter-pole shortest distance (L), a ratio of the inter-pole shortest distance (L) to an outer diameter (D) of the rotor is 0.035?L/D?0.045.
    Type: Application
    Filed: December 19, 2014
    Publication date: September 8, 2016
    Inventors: Atsushi ISHIKAWA, Kazuhiko BABA, Masahiro NIGO, Kazuchika TSUCHIDA