Patents by Inventor Masao Ohi

Masao Ohi 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).

  • Patent number: 4912834
    Abstract: A method of adjusting a thermal balance of a rotor. When obtaining a difference in shaft-vibration component of the rotor between an actual load condition and a no load condition, on the basis of detection results at a simulated load, a difference in shaft-vibration component of the rotating rotor between a no-load condition and a condition in which the rotor is heated from the outside and a difference in shaft-vibration component of the rotating rotor between a no-load condition and a condition in which the rotor is heated from the inside are detected at the simulated load. The detected differences in shaft-vibration component are converted respectively to differences in shaft-vibration component under a temperature condition at the actual load. Both the converted differences in shaft-vibration component are added to each other in a vector manner to obtain a difference in rotor shaft-vibration component at the actual load.
    Type: Grant
    Filed: August 30, 1988
    Date of Patent: April 3, 1990
    Assignee: Hitachi, Ltd.
    Inventors: Takashi Watanabe, Ryoichi Shiobara, Masayuki Furuyama, Masao Ohi
  • Patent number: 4851766
    Abstract: A fault diagnosis system for a rotor winding of rotary electric machines is disclosed, in which the rotor winding of rotary field type is excited in DC fashion by an excitation circuit, on which an AC voltage is superposed, the impedance of the rotor winding is calculated from the current and voltage of the AC portion flowing in the rotor winding, and the resulting impedance is compared with a reference impedance thereby to decide a fault, if any, of the rotor winding, thus making possible accurate diagnosis of a rotary electric machine even while it is running.
    Type: Grant
    Filed: December 9, 1987
    Date of Patent: July 25, 1989
    Assignee: Hitachi, Ltd.
    Inventors: Ryoichi Shiobara, Masao Ohi
  • Patent number: 4748363
    Abstract: A current-collecting brush apparatus is disclosed in which brushes are held slidably on a brush holder and pressed against a rotor by a brush-pressing spring. Pigtails connected to supply current to the brushes comprise a plurality of spiral conductors in parallel which are connected by being coiled in mutual opposite directions to offset the magnetic fluxes generated therein.
    Type: Grant
    Filed: February 24, 1987
    Date of Patent: May 31, 1988
    Assignees: Hitachi, Ltd., Hitachi Service Eng., Co. Ltd.
    Inventors: Takashi Watanabe, Masao Ohi, Koji Tanaka, Yoshio Takikawa, Yasuto Kondoh, Satoshi Oouchi