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).
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Patent number: 10511212Abstract: 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: GrantFiled: February 8, 2018Date of Patent: December 17, 2019Assignee: MINEBEA MITSUMI INC.Inventors: Fumitoshi Yamashita, Osamu Yamada, Shiho Ohya, Akihiro Yamane
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Publication number: 20180159407Abstract: 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: ApplicationFiled: February 8, 2018Publication date: June 7, 2018Inventors: Fumitoshi YAMASHITA, Osamu YAMADA, Shiho OHYA, Akihiro YAMANE
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Publication number: 20160072371Abstract: 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: ApplicationFiled: November 9, 2015Publication date: March 10, 2016Applicant: MINEBEA CO., LTD.Inventors: Fumitoshi YAMASHITA, Osamu YAMADA, Shiho OHYA, Akihiro YAMANE
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Patent number: 9266311Abstract: 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: GrantFiled: April 21, 2011Date of Patent: February 23, 2016Assignee: MINEBEA CO., LTD.Inventors: Fumitoshi Yamashita, Shinsaku Nishimura, Noboru Menjo
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Publication number: 20140043125Abstract: 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: ApplicationFiled: August 6, 2013Publication date: February 13, 2014Applicant: Minebea Co., Ltd.Inventors: Fumitoshi YAMASHITA, Toshinori SUZUKI, Haruhiro KOMURA
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Publication number: 20140010955Abstract: 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: ApplicationFiled: August 13, 2012Publication date: January 9, 2014Applicant: MINEBEA CO., LTD.Inventors: Fumitoshi YAMASHITA, Shiho OHYA, Shinsaku NISHIMURA
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Patent number: 8421293Abstract: 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: GrantFiled: July 16, 2008Date of Patent: April 16, 2013Assignee: Minebea Co., Ltd.Inventor: Fumitoshi Yamashita
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Patent number: 8371021Abstract: 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: GrantFiled: May 20, 2009Date of Patent: February 12, 2013Assignee: Panasonic CorporationInventors: Fumitoshi Yamashita, Kiyomi Kawamura, Yukihiro Okada, Hiroshi Murakami
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Patent number: 8329056Abstract: 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: GrantFiled: August 10, 2010Date of Patent: December 11, 2012Assignee: Minebea Co., Ltd.Inventors: Fumitoshi Yamashita, Osamu Yamada, Shiho Ohya
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Patent number: 8269391Abstract: 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: GrantFiled: June 1, 2010Date of Patent: September 18, 2012Assignee: Minebea Co., Ltd.Inventors: Fumitoshi Yamashita, Shinsaku Nishimura, Noboru Menjo
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Patent number: 8183732Abstract: 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: GrantFiled: October 20, 2011Date of Patent: May 22, 2012Assignee: Panasonic CorporationInventors: Fumitoshi Yamashita, Hiroshi Murakami, Kiyomi Kawamura
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Publication number: 20120032537Abstract: 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: ApplicationFiled: October 20, 2011Publication date: February 9, 2012Inventors: Fumitoshi YAMASHITA, Hiroshi Murakami, Kiyomi Kawamura
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Patent number: 8069552Abstract: 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: GrantFiled: August 13, 2009Date of Patent: December 6, 2011Assignee: Minebea Co., Ltd.Inventor: Fumitoshi Yamashita
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Patent number: 8072109Abstract: 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: GrantFiled: March 16, 2007Date of Patent: December 6, 2011Assignee: Panasonic CorporationInventors: Fumitoshi Yamashita, Hiroshi Murakami, Kiyomi Kawamura
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Publication number: 20110266894Abstract: 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: ApplicationFiled: April 21, 2011Publication date: November 3, 2011Applicant: MINEBEA CO., LTD.Inventors: Fumitoshi YAMASHITA, Shinsaku NISHIMURA, Noboru MENJO
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Patent number: 8044547Abstract: 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: GrantFiled: November 15, 2007Date of Patent: October 25, 2011Assignee: Panasonic CorporationInventors: Fumitoshi Yamashita, Hiroshi Murakami, Yukihiro Okada, Kiyomi Kawamura
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Patent number: 7967919Abstract: 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-shapeType: GrantFiled: May 26, 2005Date of Patent: June 28, 2011Assignee: Panasonic CorporationInventor: Fumitoshi Yamashita
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Publication number: 20110121675Abstract: 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: ApplicationFiled: July 16, 2008Publication date: May 26, 2011Applicant: MINEBEA CO., LTD.Inventor: Fumitoshi Yamashita
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Publication number: 20110074531Abstract: 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: ApplicationFiled: August 10, 2010Publication date: March 31, 2011Applicant: MINEBEA CO., LTD.Inventors: Fumitoshi YAMASHITA, Osamu Yamada, Shiho Ohya
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Patent number: 7902707Abstract: 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: GrantFiled: November 12, 2008Date of Patent: March 8, 2011Assignee: Panasonic CorporationInventors: Kiyomi Kawamura, Fumitoshi Yamashita, Hiroshi Murakami