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).

  • Publication number: 20170089983
    Abstract: 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: Application
    Filed: September 15, 2016
    Publication date: March 30, 2017
    Inventors: Tetsuji KATO, Kohji MAKI, Minori NAGATA
  • Patent number: 9506995
    Abstract: 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: Grant
    Filed: June 5, 2012
    Date of Patent: November 29, 2016
    Assignee: Hitachi, Ltd.
    Inventor: Kohji Maki
  • Publication number: 20160245851
    Abstract: 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: Application
    Filed: February 11, 2016
    Publication date: August 25, 2016
    Inventors: Tetsuji KATO, Kohji MAKI, Tomoaki HIRUTA
  • Publication number: 20150381005
    Abstract: 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: Application
    Filed: February 25, 2013
    Publication date: December 31, 2015
    Inventors: Tetsuji KATO, Kohji MAKI, Koji OBATA, Daisuke KORI
  • Publication number: 20150331051
    Abstract: 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: Application
    Filed: May 8, 2015
    Publication date: November 19, 2015
    Inventors: Kohji MAKI, Shinya YUDA, Hiroaki KOJIMA, Satoshi KIKUCHI, Hisashi ENDO
  • Patent number: 8781763
    Abstract: 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: Grant
    Filed: August 16, 2011
    Date of Patent: July 15, 2014
    Assignee: Hitachi, Ltd.
    Inventors: Shigeru Kakugawa, Masashi Kitamura, Kohji Maki, Shinji Sugimoto
  • Publication number: 20140129167
    Abstract: 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: Application
    Filed: June 5, 2012
    Publication date: May 8, 2014
    Applicant: Hitachi, Ltd.
    Inventor: Kohji Maki
  • Publication number: 20140042863
    Abstract: 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: Application
    Filed: July 12, 2013
    Publication date: February 13, 2014
    Inventors: Masayoshi OJIMA, Kohji MAKI
  • Publication number: 20130140930
    Abstract: 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: Application
    Filed: August 29, 2011
    Publication date: June 6, 2013
    Inventors: Hidetoshi Koka, Satoshi Kikuchi, Yutaka Matsunobu, Shigeru Kakugawa, Kohji Maki, Shinji Sugimoto
  • Publication number: 20130093264
    Abstract: 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: Application
    Filed: June 9, 2010
    Publication date: April 18, 2013
    Applicant: HITACHI LTD
    Inventors: Yasuaki Aoyama, Yoshitaka Iwaji, Kohji Maki
  • Publication number: 20120053866
    Abstract: 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: Application
    Filed: August 16, 2011
    Publication date: March 1, 2012
    Inventors: Shigeru KAKUGAWA, Masashi KITAMURA, Kohji MAKI, Shinji SUGIMOTO
  • Patent number: 8049369
    Abstract: 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: Grant
    Filed: March 23, 2009
    Date of Patent: November 1, 2011
    Assignee: Hitachi, Ltd.
    Inventors: Hiroki Funato, Liang Shao, Kohji Maki, George Saikalis
  • Publication number: 20100237693
    Abstract: 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: Application
    Filed: March 23, 2009
    Publication date: September 23, 2010
    Applicant: Hitachi, Ltd
    Inventors: Hiroki Funato, Liang Shao, Kohji Maki, George Saikalis
  • Patent number: 7777371
    Abstract: 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: Grant
    Filed: December 12, 2005
    Date of Patent: August 17, 2010
    Assignee: Hitachi, Ltd.
    Inventors: Houng Joong Kim, Kohji Maki, Hisao Tadokoro, Hideki Shimane, Hitoshi Shibata, Keijiro Sakai
  • Patent number: 7336077
    Abstract: 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: Grant
    Filed: November 16, 2006
    Date of Patent: February 26, 2008
    Assignee: Hitachi, Ltd.
    Inventors: Tsuyoshi Wakuda, Michiya Okada, Tomomi Kikuta, Kohji Maki, Hiroshi Morita, Shuichi Kido, Tomoo Chiba, Hideo Tsukamoto
  • Patent number: 7312542
    Abstract: 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: Grant
    Filed: May 9, 2005
    Date of Patent: December 25, 2007
    Assignee: Hitachi, Ltd.
    Inventors: Kim Houng Joong, Hiroshi Katayama, Kohji Maki
  • Publication number: 20070052421
    Abstract: 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: Application
    Filed: November 16, 2006
    Publication date: March 8, 2007
    Inventors: Tsuyoshi Wakuda, Michiya Okada, Tomomi Kikuta, Kohji Maki, Hiroshi Morita, Shuichi Kido, Tomoo Chiba, Hideo Tsukamoto
  • Patent number: 7187175
    Abstract: 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: Grant
    Filed: January 12, 2006
    Date of Patent: March 6, 2007
    Assignee: Hitachi, Ltd.
    Inventors: Tsuyoshi Wakuda, Michiya Okada, Tomomi Kikuta, Kohji Maki, Hiroshi Morita, Shuichi Kido, Tomoo Chiba, Hideo Tsukamoto
  • Patent number: 7157912
    Abstract: 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: Grant
    Filed: June 27, 2005
    Date of Patent: January 2, 2007
    Assignee: Hitachi, Ltd.
    Inventors: Kohji Maki, Tsuyoshi Wakuda
  • Patent number: 7141977
    Abstract: 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: Grant
    Filed: April 2, 2004
    Date of Patent: November 28, 2006
    Assignee: Hitachi, Ltd.
    Inventors: Tsuyoshi Wakuda, Michiya Okada, Tomomi Kikuta, Kohji Maki, Hiroshi Morita, Shuichi Kido, Tomoo Chiba, Hideo Tsukamoto