Patents by Inventor Fumitoshi Yamashita

Fumitoshi Yamashita 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: 10511212
    Abstract: A motor includes poles P having a remanence Mr of 0.9 T or more, a coercivity HcJ of 0.80 MA/m or more, and a maximum energy product (BH)max of 150 kJ/m3 or more, which sets a center point Pc of the magnetic poles in a circumferential direction on a rotor outer circumferential surface to a maximum thickness tmax, wherein when a line connecting the Pc and a rotational axis center Rc is Pc-Rc, a straight line connecting an arbitrary point Px in the circumferential direction on the rotor outer circumferential surface and the Rc is Px-Rc, an apex angle of the lines Pc-Rc and Px-Rc is ?, a number of pole pairs is Pn, a circumferential direction magnetic pole end is Pe, and a magnetic pole end biasing distance ?LPe of the circumferential direction magnetic pole ends Pe is ?×tmax (? is a coefficient).
    Type: Grant
    Filed: February 8, 2018
    Date of Patent: December 17, 2019
    Assignee: MINEBEA MITSUMI INC.
    Inventors: Fumitoshi Yamashita, Osamu Yamada, Shiho Ohya, Akihiro Yamane
  • Publication number: 20180159407
    Abstract: A motor includes poles P having a remanence Mr of 0.9 T or more, a coercivity HcJ of 0.80 MA/m or more, and a maximum energy product (BH)max of 150 kJ/m3 or more, which sets a center point Pc of the magnetic poles in a circumferential direction on a rotor outer circumferential surface to a maximum thickness tmax, wherein when a line connecting the Pc and a rotational axis center Rc is Pc-Rc, a straight line connecting an arbitrary point Px in the circumferential direction on the rotor outer circumferential surface and the Rc is Px-Rc, an apex angle of the lines Pc-Rc and Px-Rc is ?, a number of pole pairs is Pn, a circumferential direction magnetic pole end is Pe, and a magnetic pole end biasing distance ?LPe of the circumferential direction magnetic pole ends Pe is ?×tmax (? is a coefficient).
    Type: Application
    Filed: February 8, 2018
    Publication date: June 7, 2018
    Inventors: Fumitoshi YAMASHITA, Osamu YAMADA, Shiho OHYA, Akihiro YAMANE
  • Publication number: 20160072371
    Abstract: A motor includes poles P having a remanence Mr of 0.9 T or more, a coercivity HcJ of 0.80 MA/m or more, and a maximum energy product (BH)max of 150 kJ/m3 or more, which sets a center point Pc of the magnetic poles in a circumferential direction on a rotor outer circumferential surface to a maximum thickness tmax, wherein when a line connecting the Pc and a rotational axis center Rc is Pc-Rc, a straight line connecting an arbitrary point Px in the circumferential direction on the rotor outer circumferential surface and the Rc is Px-Rc, an apex angle of the lines Pc-Rc and Px-Rc is ?, a number of pole pairs is Pn, a circumferential direction magnetic pole end is Pe, and a magnetic pole end biasing distance ?LPe of the circumferential direction magnetic pole ends Pe is ?×tmax (? is a coefficient).
    Type: Application
    Filed: November 9, 2015
    Publication date: March 10, 2016
    Applicant: MINEBEA CO., LTD.
    Inventors: Fumitoshi YAMASHITA, Osamu YAMADA, Shiho OHYA, Akihiro YAMANE
  • Patent number: 9266311
    Abstract: There is provided the manufacturing method of a laminated magnet film end product, including the steps of: a first step of preparing magnet films, each of the magnet films having a thickness of 40 ?m to 300 ?m, and having a nanocrystalline structure which is magnetically isotropic; a second step of applying a self-bonding resin composition with film formability on each of the magnet films so as to prepare a plurality of self-bonding magnet films, each being composed of a magnet film and a self-bonding layer; a third step of mechanically processing each of the plurality of the self-bonding magnet films so as to be solid or hollow disc; a fourth step of preparing a laminated magnet film by laminating the plurality of self-bonding magnetic films; a fifth step of melting each self-bonding layer of the laminated magnet film and then cooling and solidifying each self-bonding layer so as to integrally rigidify the laminated magnet film; and a sixth step of magnetizing the rigidified laminated magnet film.
    Type: Grant
    Filed: April 21, 2011
    Date of Patent: February 23, 2016
    Assignee: MINEBEA CO., LTD.
    Inventors: Fumitoshi Yamashita, Shinsaku Nishimura, Noboru Menjo
  • Publication number: 20140043125
    Abstract: Provided is a method for producing a fully dense rare earth-iron-based bonded magnet, the method comprising: kneading a non-tacky thermosetting resin composition with rare earth-iron-based magnet flakes to produce a solid granular composite magnetic material; filling the granular composite magnetic material into a cavity, applying a uniaxial pressure higher than or equal to the yield stress of the thermosetting resin composition to the granular composite magnetic material so as to produce a green compact in which voids are reduced as a result of an interaction between brittle fracture of the magnet flakes and plastic deformation of the thermosetting resin composition, the rare earth-iron-based magnet flakes are piled on top of one another highly compact in the direction of the pressure axis, and the mutual positional relations of the magnet flakes are set almost regularly; and heating the green compact to cure the thermosetting resin composition constituting the green compact.
    Type: Application
    Filed: August 6, 2013
    Publication date: February 13, 2014
    Applicant: Minebea Co., Ltd.
    Inventors: Fumitoshi YAMASHITA, Toshinori SUZUKI, Haruhiro KOMURA
  • Publication number: 20140010955
    Abstract: There is provided a method of producing an ?-Fe/R2TM14B-type nanocomposite magnet where R is 9 at. % or more but less than 11.76 at. % of Nd or Pr, TM is Fe or a substance in which a portion of Fe is substituted with Co of 20 at. % or less, and B is 6 to 8 at. %. A relatively long length nanocrystalline ribbon having a coercivity of 600 kA/m or more in which a content of flakes of less than 10 mm in length is 20% or less is coated with a polymeric film and then cut into an intended length, or punched into a specific shape.
    Type: Application
    Filed: August 13, 2012
    Publication date: January 9, 2014
    Applicant: MINEBEA CO., LTD.
    Inventors: Fumitoshi YAMASHITA, Shiho OHYA, Shinsaku NISHIMURA
  • Patent number: 8421293
    Abstract: Improvement of torque densities, miniaturization and weight saving for outer rotor type motors or permanent-magnet-field-type DC motors can be efficiently achieved by high-energy densification of a magnet. However, torque pulsation or armature reaction gives negative influences thereto. Further, in application of a slotless (coreless) structure eliminating the torque pulsation or the armature reaction, the magnetic resistance of motor magnetic circuits will be enhanced. For solving the above problems, there is provided an annular magnet that is opened in a reverse direction relative to the opening direction of a U-shaped segment fabricated in constantly-directed magnetic fields, the annular magnet having an anisotropic distribution where angles relative to inner peripheral tangent lines can be continuously changed in the range of approximately 0 to 90 degrees, and having energy density (BH)max of 160 to 186 kJ/m3.
    Type: Grant
    Filed: July 16, 2008
    Date of Patent: April 16, 2013
    Assignee: Minebea Co., Ltd.
    Inventor: Fumitoshi Yamashita
  • Patent number: 8371021
    Abstract: A process of manufacturing segments, an anisotropic direction of which is continuously changed in a plane vertically by a uniform magnetic field maintained in a constant direction and a process of arranging a plurality of segments on a circumference, extruding the segments in a ring shape by rheology based on the viscous deformation of the segments, from one thrust-direction end surface of the segments, and subsequently compressing the segments from both thrust-direction end surfaces of the segments are necessarily included. A ring magnet, anisotropy of which is controlled in a continuous direction, is provided, and a source for generating a static magnetic field has energy density (BH) max?160 to 180 kJ/m3.
    Type: Grant
    Filed: May 20, 2009
    Date of Patent: February 12, 2013
    Assignee: Panasonic Corporation
    Inventors: Fumitoshi Yamashita, Kiyomi Kawamura, Yukihiro Okada, Hiroshi Murakami
  • Patent number: 8329056
    Abstract: Anisotropic rare earth-iron based resin bonded magnet comprises: [1] a continuous phase including: (1) a spherical Sm2Fe17N3 based magnetic material covered with epoxy oligomer where its average particle size is 1 to 10 ?m, its average aspect ratio ARave is 0.8 or more, and mechanical milling is not applied after Sm—Fe alloy is nitrided; (2) a linear polymer with active hydrogen group reacting to the oligomer; and (3) additive; and [2] a discontinuous phase being an Nd2Fe14B based magnetic material coated with the epoxy oligomer where its average particle size is 50 to 150 ?m, and its average aspect ratio ARave is 0.65 or more, further satisfying: [3] the air-gap ratio of a granular compound on the phases is 5% or less; and [4] a composition where crosslinking agent with 10 ?m or less is adhered on the granular compound is formed at 50 MPa or less.
    Type: Grant
    Filed: August 10, 2010
    Date of Patent: December 11, 2012
    Assignee: Minebea Co., Ltd.
    Inventors: Fumitoshi Yamashita, Osamu Yamada, Shiho Ohya
  • Patent number: 8269391
    Abstract: A micro rotor is disclosed and includes a plurality of circular or annular plate-shaped thick film magnets which each include an isotropic magnet with a thickness t1 having an in-plane remanence Mr of 0.95 T or more and a coercivity HcJ of 400 kA/m or more and a non-magnetic material with a thickness t2 adapted to isolate two adjacent isotropic magnets where the ratio of t1/t2 is eight or more and which are stacked on one another in multiple layers in the rotation axis direction, wherein at least two pole pairs are provided and a mean magnetic path of in-plane direction having a permeance (B/?oH) of five or more achieved by the magnet alone is provided, whereby eddy current is reduced. Also disclosed are a radial gap type brushless DC motor, a PM stepping motor and an electric generator which incorporate the above described micro rotor.
    Type: Grant
    Filed: June 1, 2010
    Date of Patent: September 18, 2012
    Assignee: Minebea Co., Ltd.
    Inventors: Fumitoshi Yamashita, Shinsaku Nishimura, Noboru Menjo
  • Patent number: 8183732
    Abstract: To improve tranquility and controllability of an iron core-equipped permanent magnet motor with an improved maximum energy product (BH)max by improving shape compatibility of a radial anisotropic magnet, there is provided a radial anisotropic magnet manufacturing method of fixing magnet powder in a net shape so as to maintain a magnetic anisotropic (C-axis) angle of a magnet with respect to a tangential line and for performing a deformation with a flow so as to have a predetermined circular arc shape or a predetermined annular shape. Particularly, by performing a deformation with a viscous flow or an extension flow, a deformability of the magnet is improved, and thus shape compatibility with respect to a thickness is. improved. A C-axis angle ? with respect to a tangential direction is controlled at an arbitrary position and an arbitrary angle so as to reduce cogging torque without separating a magnetic pole into segments.
    Type: Grant
    Filed: October 20, 2011
    Date of Patent: May 22, 2012
    Assignee: Panasonic Corporation
    Inventors: Fumitoshi Yamashita, Hiroshi Murakami, Kiyomi Kawamura
  • Publication number: 20120032537
    Abstract: To improve tranquility and controllability of an iron core-equipped permanent magnet motor with an improved maximum energy product (BH)max by improving shape compatibility of a radial anisotropic magnet, there is provided a radial anisotropic magnet manufacturing method of fixing magnet powder in a net shape so as to maintain a magnetic anisotropic (C-axis) angle of a magnet with respect to a tangential line and for performing a deformation with a flow so as to have a predetermined circular arc shape or a predetermined annular shape. Particularly, by performing a deformation with a viscous flow or an extension flow, a deformability of the magnet is improved, and thus shape compatibility with respect to a thickness is. improved. A C-axis angle ? with respect to a tangential direction is controlled at an arbitrary position and an arbitrary angle so as to reduce cogging torque without separating a magnetic pole into segments.
    Type: Application
    Filed: October 20, 2011
    Publication date: February 9, 2012
    Inventors: Fumitoshi YAMASHITA, Hiroshi Murakami, Kiyomi Kawamura
  • Patent number: 8069552
    Abstract: A method of manufacturing a rotor magnet for a micro rotary electric machine is provided which includes steps of: a process in which a plurality of thick films, each of which is made of nanocomposite texture composed of ?Fe and R-TM-B where R is either 10 to 20 atomic % Nd or 10 to 20 atomic % Pr, B is 5 to 20 atomic % and TM is either Fe or partly Co-substituted Fe with 0 to 16 atomic %, are formed into a laminated magnet including isotropic nano-crystalline texture which contains ?Fe and R2TM14B and which has a remanence, Mr, of 0.95 T or more; and a process where the laminated magnet is multi-polar magnetized in-plane of the thick films.
    Type: Grant
    Filed: August 13, 2009
    Date of Patent: December 6, 2011
    Assignee: Minebea Co., Ltd.
    Inventor: Fumitoshi Yamashita
  • Patent number: 8072109
    Abstract: To improve tranquility and controllability of an iron core-equipped permanent magnet motor with an improved maximum energy product (BH)max by improving shape compatibility of a radial anisotropic magnet, there is provided a radial anisotropic magnet manufacturing method of fixing magnet powder in a net shape so as to maintain a magnetic anisotropic (C-axis) angle of a magnet with respect to a tangential line and for performing a deformation with a flow so as to have a predetermined circular arc shape or a predetermined annular shape. Particularly, by performing a deformation with a viscous flow or an extension flow, a deformability of the magnet is improved, and thus shape compatibility with respect to a thickness is improved. A C-axis angle ? with respect to a tangential direction is controlled at an arbitrary position and an arbitrary angle so as to reduce cogging torque without separating a magnetic pole into segments.
    Type: Grant
    Filed: March 16, 2007
    Date of Patent: December 6, 2011
    Assignee: Panasonic Corporation
    Inventors: Fumitoshi Yamashita, Hiroshi Murakami, Kiyomi Kawamura
  • Publication number: 20110266894
    Abstract: There is provided the manufacturing method of a laminated magnet film, including the steps of: a first step of preparing a magnet film, 40 ?m to 300 ?m in thickness, provided with a nanocrystalline structure magnetically isotropic; a second step of applying a self-bonding resin composition with film formability on the magnet film preparing a self-bonding magnet film composed of the magnet film and a self-bonding layer; a third step of mechanically processing the self-bonding magnet film being solid or hollow; a fourth step of preparing the laminated magnet film by laminating the self-bonding magnet films; a fifth step of melting the self-bonding layer of the laminated magnet film and then cooling and solidifying the self-bonding layer to integrally rigidify the laminated magnet film; and a sixth step of magnetizing the rigidified laminated magnet film.
    Type: Application
    Filed: April 21, 2011
    Publication date: November 3, 2011
    Applicant: MINEBEA CO., LTD.
    Inventors: Fumitoshi YAMASHITA, Shinsaku NISHIMURA, Noboru MENJO
  • Patent number: 8044547
    Abstract: In a radial-direction gap type magnet motor, when an energy density increases, a direction change M?/?p of a static magnetic field with respect to a mechanic angle between different poles increases in an exponential manner and thus to decrease a cogging torque of the motor is not compatible to increase a torque density. In order to solve the problem, assuming that ?t denotes a mechanic angle of a stator iron core teeth, ?p denotes a mechanical angle of a magnetic pole, and M? denotes an angle of a static magnetic field with respect to a circumferential tangential line of a radial magnetic pole center, a radial-direction type magnet motor in which ?t<?p, M? in a magnetic pole center region is 75 to 90°, and M?/?p?7 is satisfied in the magnetic pole end region of ?p×0.1°, and further, a static magnetic field generating source is configured as a magnetic anisotropic magnetic pole having an energy density (BH) max?150 kJ/m3 is provided.
    Type: Grant
    Filed: November 15, 2007
    Date of Patent: October 25, 2011
    Assignee: Panasonic Corporation
    Inventors: Fumitoshi Yamashita, Hiroshi Murakami, Yukihiro Okada, Kiyomi Kawamura
  • Patent number: 7967919
    Abstract: The present invention provides a method for manufacturing a self-organized rare earth-iron bonded magnet, including: a first step of covering a rare earth-iron magnet powder with oligomer or prepolymer in which one molecule includes at least two or more reactive ground substances to provide a surface-treated magnet powder; a second step of melting and kneading stretchable polymer and the surface-treated magnet powder to coarsely crush the resultant material to provide a granule; a third step of dry blending the granule with hardener to provide a compound; a fourth step of compressing the compound under temperature conditions by which the oligomer or prepolymer, the polymer, and the hardener are caused to melt and to flow to provide a green compact; a fifth step of causing the green compact to be a self-organized rare earth-iron bonded magnet by reacting the oligomer or prepolymer, and polymer with the hardener; and a sixth step of stretching the bonded magnet to transform the shape to any of a circular-shape
    Type: Grant
    Filed: May 26, 2005
    Date of Patent: June 28, 2011
    Assignee: Panasonic Corporation
    Inventor: Fumitoshi Yamashita
  • Publication number: 20110121675
    Abstract: Improvement of torque densities, miniaturization and weight saving for outer rotor type motors or permanent-magnet-field-type DC motors can be efficiently achieved by high-energy densification of a magnet. However, torque pulsation or armature reaction gives negative influences thereto. Further, in application of a slotless (coreless) structure eliminating the torque pulsation or the armature reaction, the magnetic resistance of motor magnetic circuits will be enhanced. For solving the above problems, there is provided an annular magnet that is opened in a reverse direction relative to the opening direction of a U-shaped segment fabricated in constantly-directed magnetic fields, the annular magnet having an anisotropic distribution where angles relative to inner peripheral tangent lines can be continuously changed in the range of approximately 0 to 90 degrees, and having energy density (BH)max of 160 to 186 kJ/m3.
    Type: Application
    Filed: July 16, 2008
    Publication date: May 26, 2011
    Applicant: MINEBEA CO., LTD.
    Inventor: Fumitoshi Yamashita
  • Publication number: 20110074531
    Abstract: Anisotropic rare earth-iron based resin bonded magnet comprises: [1] a continuous phase including: (1) a spherical Sm2Fe17N3 based magnetic material covered with epoxy oligomer where its average particle size is 1 to 10 ?m, its average aspect ratio ARave is 0.8 or more, and mechanical milling is not applied after Sm—Fe alloy is nitrided; (2) a linear polymer with active hydrogen group reacting to the oligomer; and (3) additive; and [2] a discontinuous phase being an Nd2Fe14B based magnetic material coated with the epoxy oligomer where its average particle size is 50 to 150 ?m, and its average aspect ratio ARave is 0.65 or more, further satisfying: [3] the air-gap ratio of a granular compound on the phases is 5% or less; and [4] a composition where crosslinking agent with 10 ?m or less is adhered on the granular compound is formed at 50 MPa or less.
    Type: Application
    Filed: August 10, 2010
    Publication date: March 31, 2011
    Applicant: MINEBEA CO., LTD.
    Inventors: Fumitoshi YAMASHITA, Osamu Yamada, Shiho Ohya
  • Patent number: 7902707
    Abstract: An anisotropic permanent magnet motor includes a stator and a rotor opposed to teeth of the stator with a gap therebetween, and the rotor includes an anisotropic permanent magnet disposed on a surface of a rotor yoke. The anisotropic permanent magnet has an orientation direction set in a direction normal to the outer-peripheral surface in a range of both ?r°/2 from a magnetic pole center and continuously inclined toward a magnetic pole end with respect to a direction normal to the outer-peripheral surface.
    Type: Grant
    Filed: November 12, 2008
    Date of Patent: March 8, 2011
    Assignee: Panasonic Corporation
    Inventors: Kiyomi Kawamura, Fumitoshi Yamashita, Hiroshi Murakami