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).

  • Publication number: 20100308679
    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 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: Application
    Filed: June 1, 2010
    Publication date: December 9, 2010
    Applicant: MINEBEA CO., LTD.
    Inventors: Fumitoshi YAMASHITA, Shinsaku NISHIMURA, Noboru MENJO
  • Patent number: 7828988
    Abstract: An anisotropic rare-earth bonded magnet having a network boundary phase is provided by imparting melt fluidity accompanied by a slip to a composite granule and compressing and molding the composite granule in a magnetic field together with extensible polymer molecules and a chemical contact. In the bonded magnet, the maximum energy product is 147 kJ/m3 in the thickness of 1 mm, or 127 kJ/m3 in the thickness of 300 ?m. This bonded magnet contributes to increase in output and decrease in size and weight of a permanent-magnet motor.
    Type: Grant
    Filed: July 22, 2005
    Date of Patent: November 9, 2010
    Assignee: Panasonic Corporation
    Inventor: Fumitoshi Yamashita
  • Publication number: 20100218365
    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: Application
    Filed: May 20, 2009
    Publication date: September 2, 2010
    Applicant: Panasonic Corporation
    Inventors: Fumitoshi Yamashita, Kiyomi Kawamura, Yukihiro Okada, Hiroshi Murakami
  • Publication number: 20100219921
    Abstract: A rare-earth iron-based magnet with self-recoverability is provided and includes a plurality of segments, wherein the segments each include a matrix having a microstructure in which rare-earth iron-based aligned magnetic powders of at least one kind are solidified by a cross-linking reaction phase and also in which the cross-liking reaction phase and a viscous deformation phase resulting from on a viscosity flow are chemically bound to each other between the magnetic powders, and wherein while the inner and outer circumferential surfaces of the segments are constrained, the fracture surfaces of the segments, and also the segments on a needed-basis, are mutually aggregated and rigidified together by taking advantage of self-recovery function based on viscous deformation caused by heat and external force and also on cross-linking reaction.
    Type: Application
    Filed: February 16, 2010
    Publication date: September 2, 2010
    Applicant: MINEBEA CO., LTD.
    Inventors: Fumitoshi YAMASHITA, Osamu YAMADA, Shiho OHYA
  • Patent number: 7759833
    Abstract: A motor generally has a contradictory relation between decrease of cogging torque and increase of torque density. To overcome this problem, continuous direction control is provided for anisotropy with modification of magnetic poles so that the average absolute value of differences between M? and 90×sin [?{2?/(360/p)}] is set to be 3° or less, where M? is a direction of anisotropy with respect to a radial tangent line of a magnetic pole plane, ? is a mechanical angle, and p is the number of pole pairs.
    Type: Grant
    Filed: November 21, 2007
    Date of Patent: July 20, 2010
    Assignee: Panasonic Corporation
    Inventors: Fumitoshi Yamashita, Hiroshi Murakami, Yukihiro Okada, Kiyomi Kawamura
  • Publication number: 20100066192
    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: Application
    Filed: November 15, 2007
    Publication date: March 18, 2010
    Applicant: Panasonic Corporation
    Inventors: Fumitoshi Yamashita, Hiroshi Murakami, Yukihiro Okada, Kiyomi Kawamura
  • Publication number: 20100043206
    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 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: Application
    Filed: August 13, 2009
    Publication date: February 25, 2010
    Applicant: MINEBEA CO., LTD
    Inventor: Fumitoshi Yamashita
  • Publication number: 20090127960
    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: Application
    Filed: November 12, 2008
    Publication date: May 21, 2009
    Inventors: Kiyomi Kawamura, Fumitoshi Yamashita, Hiroshi Murakami
  • Publication number: 20090021097
    Abstract: A motor generally has a contradictory relation between decrease of cogging torque and increase of torque density. To overcome this problem, continuous direction control is provided for anisotropy with modification of magnetic poles so that the average absolute value of differences between M? and 90×sin [?{2?/(360/p)}] is set to be 3° or less, where M? is a direction of anisotropy with respect to a radial tangent line of a magnetic pole plane, ? is a mechanical angle, and p is the number of pole pairs.
    Type: Application
    Filed: November 21, 2007
    Publication date: January 22, 2009
    Inventors: Fumitoshi Yamashita, Hiroshi Murakami, Yukihiro Okada, Kiyomi Kawamura
  • Publication number: 20090007417
    Abstract: In order to improve tranquility and controllability of an iron core-equipped permanent magnet motor with an improvement of a maximum energy product (BH)max by improving a 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 a shape compatibility with respect to a thickness is improved. AC-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: March 16, 2007
    Publication date: January 8, 2009
    Inventors: Fumitoshi Yamashita, Hiroshi Murakami, Kiyomi Kawamura
  • Patent number: 7381280
    Abstract: Methods for manufacturing a flexible bonded magnet, and a high-efficiency small motor using the magnet are disclosed. The flexible bonded magnet is manufactured through the processes of compressing a new compound consisting of flexible thermosetting resin composite and magnetic powder, which contains thermosetting resin, thermoplastic resin, etc.; heat-curing a green sheet derived from the above process; and rolling.
    Type: Grant
    Filed: April 24, 2003
    Date of Patent: June 3, 2008
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventor: Fumitoshi Yamashita
  • Publication number: 20070246128
    Abstract: An anisotropic rare-earth bonded magnet having a network boundary phase is provided by imparting melt fluidity accompanied by a slip to a composite granule and compressing and molding the composite granule in a magnetic field together with extensible polymer molecules and a chemical contact. In the bonded magnet, the maximum energy product is 147 kJ/m3 in the thickness of 1 mm, or 127 kJ/m3 in the thickness of 300 ?m. This bonded magnet contributes to increase in output and decrease in size and weight of a permanent-magnet motor.
    Type: Application
    Filed: July 22, 2005
    Publication date: October 25, 2007
    Inventor: Fumitoshi Yamashita
  • Publication number: 20070228845
    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: Application
    Filed: May 26, 2005
    Publication date: October 4, 2007
    Inventor: Fumitoshi Yamashita
  • Patent number: 6995488
    Abstract: A permanent magnet field small DC motor includes an arc-shaped rare earth magnet of maximum thickness 1 mm or less fabricated by compression molding from rare earth iron based melt-spun flakes and a binder. The magnet is provided with a certain specific portion at both ends in the circumferential direction, which has no back yoke when the magnet is press-fit in a soft-magnetic frame. The arc-shaped rare earth magnet fabricated by compression molding from a material containing more rare earth iron based melt-spun flakes exhibits simultaneous increase of both a remanence as a function of magnetizing field and a coercivity; and hence, exhibits a well-balanced demagnetization curve even in an unsaturated magnetized state.
    Type: Grant
    Filed: August 25, 2000
    Date of Patent: February 7, 2006
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Fumitoshi Yamashita, Yuichiro Sasaki
  • Patent number: 6978533
    Abstract: A powder molded magnet manufactured by a method comprising the steps of: (1) forming a granular compound of diameter of not more than 250 ?m with a rare earth-iron rapid-quenched flake, which has not more than 150 ?m in diameter, being coarsely ground if necessary, and a binder, (2) dry-blending the granular compound with fatty acid metallic soap powder, (3) forming compressed powder from the granular compound dry-blended with the fatty acid metallic soap powder, by powder molding, and (4) heat-treating the compressed powder to a temperature higher than a thermally dissociating temperature of stabilized isocyanate.
    Type: Grant
    Filed: August 7, 2000
    Date of Patent: December 27, 2005
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Fumitoshi Yamashita, Yuichiro Sasaki
  • Patent number: 6941637
    Abstract: The method of manufacturing rare earth thick film magnet comprising a step of forming an alloy layer of 30-100 ?m thick having a general formula RXBYTMZ on a substrate by a physical deposition process, and a step of heat-treating the alloy layer to form a thick film magnetic layer having R2TM14B phase as a main phase. In the general formula, R is at least one of rare earth elements, B is boron, TM is iron or its alloy partly substituted by cobalt. X is 0.1-0.2, Y is 0.05-0.2 and Z=1-X-Y. Further, the method of the present invention includes a step of laminating a plurality of alloy layers formed on a substrate together with the substrate. A motor comprising rare earth thick film magnet of the present invention is extremely small while obtaining high output.
    Type: Grant
    Filed: March 8, 2002
    Date of Patent: September 13, 2005
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Hirotoshi Fukunaga, Masaki Nakano, Fumitoshi Yamashita
  • Publication number: 20050081961
    Abstract: Methods for manufacturing a flexible bonded magnet, and a high-efficiency small motor using the magnet are disclosed. The flexible bonded magnet is manufactured through the processes of compressing a new compound consisting of flexible thermosetting resin composite and magnetic powder, which contains thermosetting resin, thermoplastic resin, etc.; heat-curing a green sheet derived from the above process; and rolling.
    Type: Application
    Filed: April 24, 2003
    Publication date: April 21, 2005
    Inventor: Fumitoshi Yamashita
  • Patent number: 6708388
    Abstract: A permanent magnet field-type compact DC motor having a high output and a low cogging torque is made by fixing a pair of rare earth magnets mainly composed of rare earth-iron-based rapidly quenched and solidified flakes to a soft magnetic frame so as to extend along an inner peripheral surface thereof, and by unsaturation-magnetizing the rare earth magnets so that demagnetization curves at circumferentially opposite end portions of the rare earth magnets are made smaller than a demagnetization curve at a central portion of a magnetic pole of each of the rare earth magnets.
    Type: Grant
    Filed: July 10, 2002
    Date of Patent: March 23, 2004
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Fumitoshi Yamashita, Shinji Toda, Eiji Uenishi, Yuichiro Sasaki
  • Patent number: 6602569
    Abstract: There is provided a process of producing a ring shaped resin bonded magnetic member by molding a feed mixture 24 which contains a lubricant and a magnetic powder composite made of magnetic powder and a heat curable resin composition which is in a solid state at a room temperature. The process is characterized in that (1) heating an inner peripheral surface of the annular cavity 20 so as to transfer heat to the feed mixture 24 whereby heating the feed mixture to a temperature not lower than a softening temperature and below a curing temperature of the resin composition, and compressing the filled feed mixture after or during the heating; and (ii) cooling the inner peripheral surface so as to transfer heat from the heated and compressed feed mixture through the inner peripheral surface, whereby cooling the feed mixture to a temperature below the softening temperature of the resin composition so as to obtain a green compact having a ring shape.
    Type: Grant
    Filed: February 12, 2002
    Date of Patent: August 5, 2003
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Fumitoshi Yamashita, Hiroshi Ueda, Sunao Hashimoto
  • Patent number: 6599450
    Abstract: A recycling method of producing magnetic material powder from bonded magnets which are produced by mixing magnetic material powder, as raw material powder, with a binder and subjecting a mixture to molding forming, has at least the steps of: (a) separating and collecting the magnetic material powder from the bonded magnets by removing all or a prescribed percentage of the binder contained in the magnets; (b) removing all or a prescribed percentage of the particles of diameter smaller than a prescribed particle diameter from the separated and collected magnetic material powder; and (c) mixing the magnetic material powder, from which the particles of diameter smaller than the prescribed one are removed, with a virgin magnetic material powder in a prescribed mixing ratio, so as to produce a new raw material powder.
    Type: Grant
    Filed: October 26, 2000
    Date of Patent: July 29, 2003
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Takahiko Terada, Hiroshi Onishi, Yoshikazu Yamagata, Fumitoshi Yamashita