Patents by Inventor Shoichi Kawamata

Shoichi Kawamata 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: 20110163618
    Abstract: This rotating electrical machine includes a stator, a rotor having a plurality of convex portions on its surface that opposes the stator and extending along its direction of rotation, a magnet, and a frame made from magnetic material. The number of poles of the stator is the same as the number of magnetic convex poles of the rotor. The rotor is made from a plurality of plates of magnetic material, superimposed and skewed along the axial direction. A magnetic circuit is set up in the frame so that the magnetic flux of the magnet flows therein from the central portion of the rotor. And the magnet is a permanent magnet shaped as a cylinder, is single-pole magnetized along the radial direction, and is provided between the outer circumferential surface of the stator in the circumferential direction and the inner circumferential surface of the frame in the circumferential direction.
    Type: Application
    Filed: December 29, 2010
    Publication date: July 7, 2011
    Applicant: Hitachi, Ltd.
    Inventors: Hiroshi Kanazawa, Shoichi Kawamata, Shinji Sugimoto
  • Publication number: 20110163641
    Abstract: The present invention can achieve a highly efficient permanent-magnet synchronous motor that can obtain output in a high-speed area without prolonging the axis of the permanent-magnet synchronous motor. The present invention provides a highly efficient permanent-magnet synchronous motor that can obtain output in a high-speed area without prolonging the axis of the permanent-magnet synchronous motor, in which stator magnetic poles are formed by dividing a magnetic pole in each phase into a plurality of parts and placing them in a circumferential direction with respect to a rotational axis, at least one divided stator magnetic pole being made movable in the circumferential direction with respect to the rotational axis, and the phase of the movable stator is controlled.
    Type: Application
    Filed: May 3, 2010
    Publication date: July 7, 2011
    Inventors: Takayuki Koyama, Hiroshi Kanazawa, Shoichi Kawamata
  • Publication number: 20100253178
    Abstract: The present invention can achieve a highly efficient permanent-magnet synchronous motor that can obtain output in a high-speed area without prolonging the axis of the permanent-magnet synchronous motor. The present invention provides a highly efficient permanent-magnet synchronous motor that can obtain output in a high-speed area without prolonging the axis of the permanent-magnet synchronous motor, in which stator magnetic poles are formed by dividing a magnetic pole in each phase into a plurality of parts and placing them in a circumferential direction with respect to a rotational axis, at least one divided stator magnetic pole being made movable in the circumferential direction with respect to the rotational axis, and the phase of the movable stator is controlled.
    Type: Application
    Filed: December 25, 2008
    Publication date: October 7, 2010
    Inventors: Takayuki Koyama, Hiroshi Kanazawa, Shoichi Kawamata
  • Publication number: 20080018289
    Abstract: A single-phase permanent magnet motor control apparatus, in particular, a low price, flat output torque, low vibration, low noise single-phase permanent magnet motor control apparatus, and a fan and pump using such a single-phase permanent magnet motor control apparatus are provided. In a single-phase permanent magnet motor control apparatus for driving a single-phase permanent magnet motor by using a DC power supply, a converter for converting DC to AC, and a control circuit for controlling the converter, a motor current measuring unit, a terminal voltage measuring unit, a correction unit for correcting an impedance drop in motor constants, and a calculation unit for finding an induced voltage to be obtained by control are included, and a polarity of a terminal voltage is determined on the basis of a value of the found induced voltage.
    Type: Application
    Filed: July 19, 2007
    Publication date: January 24, 2008
    Inventors: Fumio Tajima, Shigeru Kakugawa, Masashi Kitamura, Shoichi Kawamata, Hiroshi Kanazawa, Takayuki Koyama, Shoji Ohiwa, Osamu Sekiguchi
  • Publication number: 20070241644
    Abstract: A single-phase motor comprising a rotor magnet, a stator core having salient poles, and a coil wound around the stator core, a rising portion and a falling portion of a voltage applied to the coil have different inclinations, wherein the salient pole is separated into three angle portions, a radius of an outer shape of the salient pole is reduced little by little with respect to a rotating direction of the rotor in a first angle portion with respect to the rotating direction of the rotor, is increased little by little with respect to the rotating direction of the rotor in a second angle portion with respect to the rotating direction of the rotor, and is increased little by little with respect to the rotating direction of the rotor in a third angle portion with respect to the rotating direction of the rotor, and a rate of increase of the third angle portion is gentler than that of the second angle portion.
    Type: Application
    Filed: April 12, 2007
    Publication date: October 18, 2007
    Inventors: Shigeru Kakugawa, Shoichi Kawamata, Fumio Tajima, Osamu Sekiguchi, Shoji Ohiwa, Yukinari Takahashi
  • Patent number: 6404152
    Abstract: In order to reduce undesired sound caused by circular ring oscillation in the diametric direction of the stator by an electromagnetic force, electromagnetic force drift memory stores a drift information of the electromagnetic force causing the circular ring oscillation of the stator. This electromagnetic force drift information is read out according to the position information &thgr; and is supplied to a correction coefficient generating circuitry. Correction coefficient generating circuitry corrects the amplitude component of the activation current wave from by forming correction coefficient &bgr; (t) of the activation current so as to cancel the electromagnetic force harmonic component in the diametric direction which component is the component of the circular ring oscillation of the stator.
    Type: Grant
    Filed: January 28, 2000
    Date of Patent: June 11, 2002
    Assignee: Hitachi, Ltd.
    Inventors: Takashi Kobayashi, Fumio Tajima, Shoichi Kawamata, Yutaka Matsunobu, Ryoso Masaki, Suetaro Shibukawa, Osamu Koizumi