Patents by Inventor Kohji Maki
Kohji Maki 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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Publication number: 20170089983Abstract: A rotary machine diagnostic system includes: a current measurement unit for measuring a leakage current of a rotary machine; a voltage measurement unit for measuring a voltage of the rotary machine corresponding to the flowing leakage current; and a data processing unit. The data processing unit has a function of performing transient response analysis on a predetermined equivalent circuit model, which is equivalent to a leakage current path of the rotary machine, using current data and voltage data having a predetermined time width which are respectively measured at predetermined time intervals by the current measurement unit and the voltage measurement unit, and a function of extracting parameters of the equivalent circuit of the leakage current path.Type: ApplicationFiled: September 15, 2016Publication date: March 30, 2017Inventors: Tetsuji KATO, Kohji MAKI, Minori NAGATA
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Patent number: 9506995Abstract: The present invention provides a magnetic field analysis program and a magnetic field analysis method for calculating inductance related to an AC magnetic field superimposed on a DC magnetic field with a high degree of accuracy at high speed.Type: GrantFiled: June 5, 2012Date of Patent: November 29, 2016Assignee: Hitachi, Ltd.Inventor: Kohji Maki
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Publication number: 20160245851Abstract: An anomaly diagnosis system is provided that includes: a current-value obtaining part 111 that obtains a value of an AC current inputted to or outputted from a device to be diagnosed; a frequency analyzing part 112 that converts the current values obtained at intervals into a frequency spectrum which correlates a current intensity with a frequency; an anomaly-judging-value calculating part 113 that calculates at intervals a frequency width of the frequency spectrum at a current intensity “As” satisfying As=m×At (0<m<1), where “At” is a peak current intensity associated with an analysis frequency which is an integer multiple of a frequency of the AC current; and a judging part 114 that judges whether the frequency width is wider than that in a normal condition and, if it holds true, judges that the device is in an anomalous condition.Type: ApplicationFiled: February 11, 2016Publication date: August 25, 2016Inventors: Tetsuji KATO, Kohji MAKI, Tomoaki HIRUTA
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Publication number: 20150381005Abstract: The present invention aims to provide a rotary machine in which deterioration or a burnout of a corona prevention layer in the vicinity of a slot outlet of a stator can be suppressed from occurring. The present invention includes a stator that has a stator core, and a rotor that is arranged so as to face the stator and is rotatably held. In the rotary machine in which a stator coil having a low-resistance corona prevention layer wound around is mounted on the stator core, a conductive member is formed on the stator coil at an end portion of the stator so as to have a structure in which a gap with respect to the stator coil is widened as the conductive member is positioned away from the stator core in a rotary shaft direction of the rotary machine.Type: ApplicationFiled: February 25, 2013Publication date: December 31, 2015Inventors: Tetsuji KATO, Kohji MAKI, Koji OBATA, Daisuke KORI
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Publication number: 20150331051Abstract: Provided is a deterioration diagnosis system which diagnoses deterioration of an N-phase rotational machine (N denotes a natural number). The deterioration diagnosis system includes a first current sensor to be attached individually to at least lead wires of (N-1)-phases in a rotational machine, the first current sensor being able to detect a current amplitude arising from a plurality of deterioration causes, and a second current sensor to be attached collectively to the lead wires of all phases in the rotational machine, the second current sensor being able to detect a current amplitude arising from a plurality of deterioration causes.Type: ApplicationFiled: May 8, 2015Publication date: November 19, 2015Inventors: Kohji MAKI, Shinya YUDA, Hiroaki KOJIMA, Satoshi KIKUCHI, Hisashi ENDO
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Patent number: 8781763Abstract: A method for analyzing an operating point of a permanent magnet performs electromagnetic field analysis based on a B-H curve of the permanent magnet and element data concerning a finite number of elements into which the permanent magnet is divided to obtain the operating point of the permanent magnet. The method includes the steps of storing data of inputted B-H curve; obtaining magnetic flux densities and magnetic fields in plural regions of the permanent magnet by performing the electromagnetic field analysis based on the data of the B-H curve; and obtaining the operating point of each of the elements based on the result of the electromagnetic field analysis by employing a variable, the variable continuously varying in a first quadrant, in a second quadrant, in a third quadrant, and over these quadrants of the B-H curve and linearly varying with respect to the magnetic flux density and magnetic field.Type: GrantFiled: August 16, 2011Date of Patent: July 15, 2014Assignee: Hitachi, Ltd.Inventors: Shigeru Kakugawa, Masashi Kitamura, Kohji Maki, Shinji Sugimoto
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Publication number: 20140129167Abstract: The present invention provides a magnetic field analysis program and a magnetic field analysis method for calculating inductance related to an AC magnetic field superimposed on a DC magnetic field with a high degree of accuracy at high speed.Type: ApplicationFiled: June 5, 2012Publication date: May 8, 2014Applicant: Hitachi, Ltd.Inventor: Kohji Maki
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Publication number: 20140042863Abstract: In a brushed direct current motor including a stator that is provided with 2×P magnetic poles (P is odd and greater than or equal to three), an armature core rotatably held with respect to the stator and includes P×N±2 teeth (N is an even and greater than or equal to four) in a circumferential direction, a commutator held so as to integrally rotate with the armature core and includes commutator segments, the number of the commutator segments being the same as that of the teeth, a winding wound around the teeth in a double-wave form, and two anode brushes and two cathode brushes arranged in sliding contact with the commutator, a width angle WB of each of the brushes in sliding contact with the commutator is set so as to satisfy a relation of “WB>WP+WI”.Type: ApplicationFiled: July 12, 2013Publication date: February 13, 2014Inventors: Masayoshi OJIMA, Kohji MAKI
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Publication number: 20130140930Abstract: Electric rotating machine suppressing narrowing of a magnetic path caused by a skin effect in a housing to increase torque, including stator core having e.g. core back and teeth; stator windings wound around the teeth; stator including stator core and stator windings; housing composed of a magnetic body accommodating the stator; rotor disposed for rotation on an inner circumferential side of the stator. An air gap is provided between an inside wall of the housing and an outer circumferential surface of core back. The core back has projections on a radial back surface of a portion where the teeth are provided. The projections are each provided to be continuous in an axial direction and have tip portions in contact with inside wall of the housing. The air gap may be defined by the inside wall of the housing, the outer circumferential surface of the core back and the projections.Type: ApplicationFiled: August 29, 2011Publication date: June 6, 2013Inventors: Hidetoshi Koka, Satoshi Kikuchi, Yutaka Matsunobu, Shigeru Kakugawa, Kohji Maki, Shinji Sugimoto
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Publication number: 20130093264Abstract: The present invention provides a linear motor where a load onto a supporting mechanism and the ripple of force are lessened and the ripple can be adjusted. As a leakage flux between the magnetic poles can be reduced by being configured by plural magnetic poles arranged with a magnet arranged on a mover held between them, a core that continuously connects the magnetic poles that holds the magnet of the mover between them, windings are integrally wound onto the plural magnetic poles and the mover formed by a row of magnets the magnetic poles of which are alternately arranged or a row of magnets the polarity of which is alternately arranged and magnetic materials, by arranging the plural magnetic poles arranged with the magnet held between and the plural magnetic poles provided with the core that continuously connects the magnetic poles.Type: ApplicationFiled: June 9, 2010Publication date: April 18, 2013Applicant: HITACHI LTDInventors: Yasuaki Aoyama, Yoshitaka Iwaji, Kohji Maki
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Publication number: 20120053866Abstract: A method for analyzing an operating point of a permanent magnet performs electromagnetic field analysis based on a B-H curve of the permanent magnet and element data concerning a finite number of elements into which the permanent magnet is divided to obtain the operating point of the permanent magnet. The method includes the steps of storing data of inputted B-H curve; obtaining magnetic flux densities and magnetic fields in plural regions of the permanent magnet by performing the electromagnetic field analysis based on the data of the B-H curve; and obtaining the operating point of each of the elements based on the result of the electromagnetic field analysis by employing a variable, the variable continuously varying in a first quadrant, in a second quadrant, in a third quadrant, and over these quadrants of the B-H curve and linearly varying with respect to the magnetic flux density and magnetic field.Type: ApplicationFiled: August 16, 2011Publication date: March 1, 2012Inventors: Shigeru KAKUGAWA, Masashi KITAMURA, Kohji MAKI, Shinji SUGIMOTO
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Patent number: 8049369Abstract: A controller for a power inverter having a gate assembly with an alternating current power output. A gate driver controls the activation of the gate assembly while a processor controls the operation of the gate driver. A current sensor has an output signal representative of the current at the power output. A noise detector circuit provides an output signal to the processor of the frequency of electromagnetic noise in the power inverter and the processor is programmed to sample the current from the current sensor at the frequency of the noise.Type: GrantFiled: March 23, 2009Date of Patent: November 1, 2011Assignee: Hitachi, Ltd.Inventors: Hiroki Funato, Liang Shao, Kohji Maki, George Saikalis
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Publication number: 20100237693Abstract: A controller for a power inverter having a gate assembly with an alternating current power output. A gate driver controls the activation of the gate assembly while a processor controls the operation of the gate driver. A current sensor has an output signal representative of the current at the power output. A noise detector circuit provides an output signal to the processor of the frequency of electromagnetic noise in the power inverter and the processor is programmed to sample the current from the current sensor at the frequency of the noise.Type: ApplicationFiled: March 23, 2009Publication date: September 23, 2010Applicant: Hitachi, LtdInventors: Hiroki Funato, Liang Shao, Kohji Maki, George Saikalis
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Patent number: 7777371Abstract: The conventional linear drive apparatus has the problem that in constructing a linear motor of a multiphase structure by connecting a plurality of armature units, the length of the armature becomes longer in proportion to the number of the phases, thus limiting the locations where the apparatus can be installed. The problem is solved by a linear drive apparatus comprising a plurality of armature units 3 formed by a magnetic material on which a conductor coil 4 is disposed, and an armature comprising an arrangement of the armature units 3. The armature units 3 comprise a plurality of opposing portions having opposing magnetic pole teeth. The magnetic pole teeth of adjacent opposing portions are arranged in an interdigitated manner. A secondary member 6 is disposed between magnetic pole teeth of the opposing portions. The armature units 3 comprise the coil 4 arranged on opposite sides thereof in an alternating manner.Type: GrantFiled: December 12, 2005Date of Patent: August 17, 2010Assignee: Hitachi, Ltd.Inventors: Houng Joong Kim, Kohji Maki, Hisao Tadokoro, Hideki Shimane, Hitoshi Shibata, Keijiro Sakai
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Patent number: 7336077Abstract: A magnet for an NMR analyzer includes a superconductor coil for generating a magnetic field in a magnetic space surrounded by the superconductor coil. The superconductor coil has a shim coil group disposed at least one of inside and outside of the superconducting coil. The superconducting coil provides a first access port for receiving a probe inserted into the magnetic space along a central axis thereof and a second access port having one end for receiving a sample tube containing a sample inserted into the magnetic space in a direction transverse to the central axis of the magnetic space. The second access port is open at an other end thereof.Type: GrantFiled: November 16, 2006Date of Patent: February 26, 2008Assignee: Hitachi, Ltd.Inventors: Tsuyoshi Wakuda, Michiya Okada, Tomomi Kikuta, Kohji Maki, Hiroshi Morita, Shuichi Kido, Tomoo Chiba, Hideo Tsukamoto
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Patent number: 7312542Abstract: To reduce the magnetic flux leakage through the gap between magnetic pole teeth of an armature so as to reduce the magnetic attraction force generated between the armature and a needle, an armature unit is provided with two magnetic poles, on the top of which are magnetic pole teeth protruding toward the opposing magnetic pole, where the magnetic pole teeth of the magnetic pole are arranged at two heights, upper and lower, and the magnetic pole teeth of the opposing magnetic pole are arranged at two heights, upper and lower, so that the magnetic flux flows upward and downward alternately between the upper and lower magnetic pole teeth. The needle equipped with permanent magnets moves relatively in the gap between the upper and lower magnetic pole surfaces of the armature unit.Type: GrantFiled: May 9, 2005Date of Patent: December 25, 2007Assignee: Hitachi, Ltd.Inventors: Kim Houng Joong, Hiroshi Katayama, Kohji Maki
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Publication number: 20070052421Abstract: A magnet for an NMR analyzer includes a superconductor coil for generating a magnetic field in a magnetic space surrounded by the superconductor coil. The superconductor coil has a shim coil group disposed at least one of inside and outside of the superconducting coil. The superconducting coil provides a first access port for receiving a probe inserted into the magnetic space along a central axis thereof and a second access port having one end for receiving a sample tube containing a sample inserted into the magnetic space in a direction transverse to the central axis of the magnetic space. The second access port is open at an other end thereof.Type: ApplicationFiled: November 16, 2006Publication date: March 8, 2007Inventors: Tsuyoshi Wakuda, Michiya Okada, Tomomi Kikuta, Kohji Maki, Hiroshi Morita, Shuichi Kido, Tomoo Chiba, Hideo Tsukamoto
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Patent number: 7187175Abstract: A magnet for an NMR an analyzer includes a superconductor coil which is operated under a permanent current mode so as to generate a magnetic field in a space surrounded by the superconductor coil, and which enables a sample to be inserted into a measurement space in the magnetic space for analization. The superconductor coil includes a first access port for enabling access to the measurement space and a second access port for enabling insertion of the sample into the measurement space in a direction different from a direction of the first access port. An effective diameter of the first access port is larger than an effective diameter of the second access port when the effective diameters of the first and second access ports are defined as a diameter of a cylinder that is insertable into the first and second access ports.Type: GrantFiled: January 12, 2006Date of Patent: March 6, 2007Assignee: Hitachi, Ltd.Inventors: Tsuyoshi Wakuda, Michiya Okada, Tomomi Kikuta, Kohji Maki, Hiroshi Morita, Shuichi Kido, Tomoo Chiba, Hideo Tsukamoto
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Patent number: 7157912Abstract: At least one superconducting shim coil is wound around a cylinder member disposed approximately coaxially with a group of superconducting main coils, and the positions in the winding center locus in an axial direction change approximately in accordance with a function where a sine or cosine function with a cycle of (360/m) degrees (m; an integer of one or more) in a circumferential direction is mixed with a sine or cosine function with a cycle of (360/(m+2)) degrees.Type: GrantFiled: June 27, 2005Date of Patent: January 2, 2007Assignee: Hitachi, Ltd.Inventors: Kohji Maki, Tsuyoshi Wakuda
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Patent number: 7141977Abstract: To access a measurement space located at the center of the magnet, an access port is provided in the direction of the magnet's axis, a clearance is provided in the coil winding portion, and another access port passes through the clearance so that a sample can be positioned perpendicularly to the coil axis. According to this configuration, an access port passing through the coil winding portion can be smaller than the access port passing through the coil axis, a sample is inserted from the access port, and a probe is inserted from the access port passing through the magnet axis, and thus the clearance can be minimized.Type: GrantFiled: April 2, 2004Date of Patent: November 28, 2006Assignee: Hitachi, Ltd.Inventors: Tsuyoshi Wakuda, Michiya Okada, Tomomi Kikuta, Kohji Maki, Hiroshi Morita, Shuichi Kido, Tomoo Chiba, Hideo Tsukamoto