Patents by Inventor Hirofumi Houjou
Hirofumi Houjou 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: 8445105Abstract: An iron-based magnetic powder for dust cores has layers of phosphoric acid-based film and silicone resin film sequentially formed on the surface thereof. The phosphoric acid-based film contains at least one element selected from the group consisting of Co, Na, S, Si, and W. The iron-based powder effectively keeps insulation among iron powder particles, excels in mechanical strength even though the amount of insulating material is reduced due to achieve high-density forming, and exhibits good thermal stability necessary for electrical insulating properties even after high-temperature heat treatment.Type: GrantFiled: August 2, 2007Date of Patent: May 21, 2013Assignee: Kobe Steel, Ltd.Inventors: Hiroyuki Mitani, Nobuaki Akagi, Hirofumi Houjou, Chio Ishihara, Makoto Iwakiri, Sohei Yamada, Yasukumi Mochimizo
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Patent number: 8409707Abstract: The invention relates to an iron-based soft magnetic powder for a dust core, wherein a film comprising Fe and Co, a phosphoric acid-based chemical conversion film and a silicone resin film are formed in this order on the surface of an iron-based soft magnetic powder, and to a dust core obtained by molding the iron-based soft magnetic powder for a dust core. The invention also relates to an iron-based soft magnetic powder for a dust core formed by coating the surface of an iron-based soft magnetic powder with an insulating film, wherein the powder has a particle diameter of from 45 ?m to 180 ?m, the insulating film is composed of two layers in which a lower layer composed of a phosphoric acid-based chemical conversion film and an upper layer composed of a silicone resin film, and each of the films has a thickness of from 100 nm to 280 nm, and to a dust core obtained by molding the iron-based soft magnetic powder for a dust core.Type: GrantFiled: July 2, 2008Date of Patent: April 2, 2013Assignee: Kobe Steel, Ltd.Inventors: Hiroyuki Mitani, Nobuaki Akagi, Hirofumi Houjou
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Patent number: 8236087Abstract: The present invention relates to an iron-base powder for a powder core, wherein when cross-sections of at least 50 iron-base powders are observed and a crystal grain size distribution containing at least a maximum crystal grain size is determined by measuring a crystal grain size of each iron-base powder, 70% or more of the measured crystal grains are a crystal grain having a crystal grain size of 50 ?m or more. According to the iron-base powder of the invention, a coercivity of the powder core can be made small and a hysteresis loss can be reduced.Type: GrantFiled: September 11, 2007Date of Patent: August 7, 2012Assignees: Kobe Steel, Ltd., Hitachi Powdered Metals Co., Ltd.Inventors: Hiroyuki Mitani, Nobuaki Akagi, Hirofumi Houjou, Chio Ishihara, Makoto Iwakiri, Sohei Yamada, Yasukuni Mochimizo
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Publication number: 20100188179Abstract: The invention relates to an iron-based soft magnetic powder for a dust core, wherein a film comprising Fe and Co, a phosphoric acid-based chemical conversion film and a silicone resin film are formed in this order on the surface of an iron-based soft magnetic powder, and to a dust core obtained by molding the iron-based soft magnetic powder for a dust core. The invention also relates to an iron-based soft magnetic powder for a dust core formed by coating the surface of an iron-based soft magnetic powder with an insulating film, wherein the powder has a particle diameter of from 45 ?m to 180 ?m, the insulating film is composed of two layers in which a lower layer composed of a phosphoric acid-based chemical conversion film and an upper layer composed of a silicone resin film, and each of the films has a thickness of from 100 nm to 280 nm, and to a dust core obtained by molding the iron-based soft magnetic powder for a dust core.Type: ApplicationFiled: July 2, 2008Publication date: July 29, 2010Applicant: KABUSHIKI KAISHA KOBE SEIKO SHO (KOBE STEEL, LTD.)Inventors: Hiroyuki Mitani, Nobuaki Akagi, Hirofumi Houjou
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Publication number: 20100051851Abstract: Disclosed herein is an iron powder for dust cores which effectively keeps insulation among iron powder particles and excels in mechanical strength even though the amount of insulating material is reduced to achieve high-density forming and which also exhibits good thermal stability necessary for electrical insulating properties even after heat treatment at high temperatures. The iron-based magnetic powder has layers of phosphoric acid-based film and silicone resin film sequentially formed on the surface thereof, said phosphoric acid-based film containing at least one element selected from the group consisting of Co, Na, S, Si, and W.Type: ApplicationFiled: August 2, 2007Publication date: March 4, 2010Applicant: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.)Inventors: Hiroyuki Mitani, Nobuaki Akagi, Hirofumi Houjou, Chio Ishihara, Makoto Iwakiri, Sohei Yamada, Yasukumi Mochimizo
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Publication number: 20090242825Abstract: An iron-based soft magnetic powder for dust core includes an iron-based soft magnetic matrix powder, and arranged thereon in the following order, a phosphate coating and a silicone resin coating. The phosphate coating contains P, Co, Na, and S in combination with at least one of Al and Cs. This iron powder for dust core has superior mechanical strength, in which effective insulation is achieved between iron powdery particles even when the amount of an insulating material is reduced for realizing high-density molding. The iron powder for dust core is also superior in thermal stability, so that electrical insulation is maintained even after a heat treatment at high temperatures.Type: ApplicationFiled: February 10, 2009Publication date: October 1, 2009Applicant: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd)Inventors: Takeshi OHWAKI, Kasumi Yanagisawa, Hiroyuki Mitani, Satoshi Nishida, Hirofumi Houjou, Nobuaki Akagi
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Publication number: 20090226751Abstract: The present invention relates to an iron-base powder for a powder core, wherein when cross-sections of at least 50 iron-base powders are observed and a crystal grain size distribution containing at least a maximum crystal grain size is determined by measuring a crystal grain size of each iron-base powder, 70% or more of the measured crystal grains are a crystal grain having a crystal grain size of 50 ?m or more. According to the iron-base powder of the invention, a coercivity of the powder core can be made small and a hysteresis loss can be reduced.Type: ApplicationFiled: September 11, 2007Publication date: September 10, 2009Applicants: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel Ltd.), Hitachi Powdered Metals Co., Ltd.Inventors: Hiroyuki Mitani, Nobuaki Akagi, Hirofumi Houjou, Chio Ishihara, Makoto Iwakiri, Sohei Yamada, Yasukuni Mochimizo
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Patent number: 6749767Abstract: A mixed powder useful as a starting material for dust core comprises a uniform mixture of a soft magnetic powder and a binder resin so that the resultant dust core has an electric resistance capable of suppressing an eddy current between the soft magnetic powdery particles and high mechanical strength at room temperatures and also at high temperatures. In the mixed powder, the binder resin is made of a phenolic resin powder which has a methylol groups in the molecule and preferably has an average particle size of 30 &mgr;m or below and wherein when the phenolic resin powder is dissolved in boiling methanol in large excess, a content of an undissolved matter is at least 4 wt % based on the total of the phenolic resin. A dust core obtained from the mixed powder and its fabrication method are also described.Type: GrantFiled: March 19, 2002Date of Patent: June 15, 2004Inventors: Hiroyuki Mitani, Tsukasa Yuri, Kazuhisa Fujisawa, Yoshikazu Seki, Masahiro Murakami, Hirofumi Houjou
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Publication number: 20030047706Abstract: A mixed powder useful as a starting material for dust core comprises a uniform mixture of a soft magnetic powder and a binder resin so that the resultant dust core has an electric resistance capable of suppressing an eddy current between the soft magnetic powdery particles and high mechanical strength at room temperatures and also at high temperatures. In the mixed powder, the binder resin is made of a phenolic resin powder which has a methylol groups in the molecule and preferably has an average particle size of 30 &mgr;m or below and wherein when the phenolic resin powder is dissolved in boiling methanol in large excess, a content of an undissolved matter is at least 4 wt % based on the total of the phenolic resin. A dust core obtained from the mixed powder and its fabrication method are also described.Type: ApplicationFiled: March 19, 2002Publication date: March 13, 2003Applicant: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd)Inventors: Hiroyuki Mitani, Tsukasa Yuri, Kazuhisa Fujisawa, Yoshikazu Seki, Masahiro Murakami, Hirofumi Houjou