Kobe Steel, Ltd.

Other

Kabushiki Kaisha Kobe Seiko Sho

Hokkaido University

Hitachi Powdered Metals Co., Ltd.

Kabushiki Kaisha Kobe Seiko Sho (kobe Steel, Ltd.)

Hiroyuki Mitani

Koji Inoue

Hirofumi Hojo

Nobuaki Akagi

Hirofumi Houjou

Kenichi Inoue

Takeo Miyamura

Tomotsuna Kamijo

Osamu Ozaki

Chio Ishihara

Takehiro Tsuchida

Takeshi Ohwaki

Yoshikazu Seki

Makoto Iwakiri

Sohei Yamada

Kazuhisa Fujisawa

Katsura Kajihara

Hiroyuki Takamatsu

Hideo Fujii

Hiroshi Hashimoto

Masamichi Chiba

Kyoji Zaitsu

Eiichiro Yoshikawa

Takashi Hase

Naoya Fujiwara

Masatsugu Takemoto

Masahiro Murakami

Masakatsu Maruyama

Masaaki Sato

Yuji Taniguchi

Yuichi Seki

Yasushi Maeda

Kasumi Yanagisawa

Akihiko Kagawa

Tetsuya Sawayama

Chikara Ichihara

Yasukumi Mochimizo

Yasukuni Mochimizo

Satomi Sato

Tsukasa Yuri

The present invention pertains to: a powder mixture for powder magnetic core obtained by mixing a lubricant, a solid lubricant, and a soft magnetic powder coated with an insulating coating, wherein a lubricant content is 0.1% by mass or more and 0.8% by mass and a solid lubricant content is 0.01% by mass or more and 0.2% by mass or less; and a powder magnetic core in which the powder mixture is used.

Powder mixture for powder magnetic core, and powder magnetic core

An iron-based soft magnetic powder for dust core having a high magnetic flux density, maintaining high electric insulation even after annealing, and more excellent in the mechanical strength in which a coating film having a phosphate conversion coating film is formed on the surface thereof and the peak height for the absorption of hydroxyl groups formed at 3700 cmto 2500 cmis 0.04 or more being indicated by absorbance when the coating film is analyzed by infrared diffuse reflectance spectroscopy.

Iron-based soft magnetic powder for dust core, method for manufacturing the same, and dust core

Provided is a so-called Lundell-type generator capable of avoiding generation of eddy current in rotor iron-cores without complicated structure. The generator includes a stator, a rotary shaft, first and second rotor iron-cores, and a rotor coil. Each rotor iron-core includes a base and rotor magnetic-pole portions extending axially from the base, the rotor coil disposed on the inside thereof. Each rotor iron-core is formed of a plurality of unit plates stacked axially. The unit plates integrally include respective basal plate portions stacked to form the bases and a plurality of magnetic-pole plate portions stacked to form the rotor magnetic-pole plate portions stacked to form the rotor magnetic-pole portions.

Generator

Provided is soft magnetic powder used to manufacture a dust core having good mechanical strength and superior formability while iron loss is reduced. The soft magnetic powder for dust cores according to the invention is soft magnetic mixed powder that includes pure iron powder and soft magnetic iron-base alloy powder, wherein the proportion of the soft magnetic iron-base alloy powder in the mixture is 5 to 60 mass %, the ratio of the modes of the particle size distributions of the soft magnetic iron-base alloy powder and the pure iron powder ((the mode of the particle size distribution of the soft magnetic iron-base alloy powder)/(the mode of the particle size distribution of the pure iron powder)) is 0.9 or more and less than 5, and the ratio R/Ris 1.2 or more, where Ris the mass proportion of soft magnetic iron-base alloy powder in mixed powder with a particle size of D50 or more based on the mass fraction, and Ris the mass proportion of soft magnetic iron-base alloy powder in mixed powder with a particle size of less than D50 based on the mass fraction.

Soft magnetic mixed powder

Disclosed is an iron-based soft magnetic powder obtained by preparing an iron-oxide-based soft magnetic powder through water atomization, and thermally reducing the iron-oxide-based soft magnetic powder. The iron-based soft magnetic powder has an average particle size of 100 &#x3bc;m or more and has an interface density of more than 0 &#x3bc;mand less than or equal to 2.6&#xd7;10&#x3bc;m, where the interface density is determined from a cross-sectional area (&#x3bc;m) and a cross-sectional circumference (&#x3bc;m) of the iron-based soft magnetic powder. The iron-based soft magnetic powder obtained by preparing an iron-oxide-based soft magnetic powder through water atomization and thermally reducing the iron-oxide-based soft magnetic powder, when used for the production of a dust core, can give a dust core having a low coercive force. Also disclosed is a duct core having a low coercive force and exhibiting superior magnetic properties.

Iron-based soft magnetic powder and production method thereof

A powder magnetic core which exhibits a high compact density and a reduced iron loss can be obtained by compacting a soft magnetic powder in which the mass ratio of soft magnetic powder particles that pass through a filter having an opening of 75 &#x3bc;m is 95 mass % or higher relative to the whole amount of the soft magnetic powder and which has a mean strain of less than 0.100%.

Iron powder for powder magnetic core and process for producing powder magnetic core

Provided is an iron-based soft magnetic powder for dust core having a less coercive force, which is obtained by specifying the amount of inclusions in the iron-based powder for dust core, and at the same time, capable of decreasing the coercive force of a dust core produced using the iron-based soft magnetic powder. The iron-based soft magnetic powder for dust core is characterized by that when the cross-section of the iron-based soft magnetic powder particle is observed with a scanning electron microscope, the number of inclusions having an equivalent circle diameter from 0.1 to 3 &#x3bc;m is 1&#xd7;10pieces/mmor less and the number of inclusions having an equivalent circle diameter exceeding 3 &#x3bc;m is 10 pieces/mmor less.

Iron-based soft magnetic powder for dust core, preparation process thereof, and dust core

Disclosed is a brushless motor (A) which is an axial gap type brushless motor (A) wherein stators (A,A) comprising a coil () and a rotor () comprising a permanent magnet () are arranged with a gap therebetween in the axial direction. The coil () is a band-like wire which is spirally wound such that the width direction of the band-like wire generally coincides with the direction of the magnetic flux that is generated by the permanent magnet () of the rotor (). Consequently, the axial gap type brushless motor (A) having the above-described structure can be further reduced in eddy current loss in comparison to conventional brushless motors.

Axial gap type brushless motor

An axial motor includes a rotor arranged between a pair of stators with coils. In the rotor, a plurality of permanent magnets sandwiched between pairs of first magnetic materials and a plurality of second magnetic materials are alternately arranged in a rotation direction while gaps are provided therebetween. Since the permanent magnets are sandwiched by the first magnetic materials in the thus constructed axial motor, a field-weakening control can be performed. Since the second magnetic materials are provided, a reluctance torque can be generated. Further, since the gaps are provided, more magnetic fluxes generated from the permanent magnets can be caused to flow toward the coils. Therefore, the thus constructed axial motor can achieve a higher output, higher torque, higher efficiency, and miniaturization.

Axial motor

Provided is a reactor that enables high inductance to be generated with stability in a wide current range, while minimizing noise, processing cost, and eddy-current loss. The reactor (D) has the ratio (t/W) of the width (W) to the thickness (t) of a conductive member that composes an air-core coil configured to be 1 or less, and preferably, 1/10 or less. Furthermore, the reactor also has the absolute value of a value ((L&#x2212;L)/L) that has had: the difference (L&#x2212;L) between; the space interval (L) between an inner wall face of a first core member () and an inner wall face of a second core member (), at the innermost circumference position of the air-core coil (); and the space (L) between the inner wall face of the first core member () and the inner wall face of the second core member (), at the outermost circumference position of the air-core coil (); divided by an average value (L); configured to be 1/50 or less. The ratio (R/W) of the radius (R), from the axis-center (O) of the air-core coil () to the outer circumference of the air-core coil (), to the width (W) of the air-core coil () (conductive member), is 2=R/W=4.

Reactor

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.

Iron-based soft magnetic powder for dust core, method for production thereof, and dust core

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 &#x3bc;m to 180 &#x3bc;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.

Iron-based soft magnetic powder for dust core and dust core

Provided is a dust core excellent in flux density, iron loss, and mechanical strength. A production process of a dust core according to the invention includes a step of compacting a mixture obtained by mixing an iron-based soft magnetic powder for powder compact having a phosphate conversion coating film on the surface of an iron-based soft magnetic powder with a lubricant to obtain a powder compact, a heat treatment step of heating the resulting powder compact at 550&#xb0; C. or more but not more than 650&#xb0; C. in an inert atmosphere, and a heat treatment step of heating the heat-treated powder compact at 420&#xb0; C. or more but not more than 530&#xb0; C. in an oxidizing atmosphere.

Production process of dust core and dust core obtained thereby

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 &#x3bc;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.

Powder core and iron-base powder for powder core

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.

Powder for high strength dust core, high strength dust core and method for making same

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Kobe, Japan

Hiroyuki Mitani