Patents by Inventor Haruki Hagiwara

Haruki Hagiwara 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).

  • Pump turbine, method of controlling thereof, and method of stopping thereof
    Patent number: 6602044
    Abstract: A pump turbine includes a runner connected to a generator motor, a water discharge controller for adjusting the quantity of water passing through the runner and a governor for detecting a rotational speed of the runner and controlling the water discharge controller to get a predetermined rotational speed of the runner. Upon a load rejection which shuts off the generator motor from an electric power system, the governor is controlled to make a target speed value of the runner after a load rejection higher than a target speed value before the load rejection. The target speed value is a reference speed to be compared with actual speed so that the governor determines when or how to open or close a water discharge controller in response to a balance between the two speeds.
    Type: Grant
    Filed: October 27, 2000
    Date of Patent: August 5, 2003
    Inventors: Takao Kuwabara, Kei Katayama, Hiroto Nakagawa, Haruki Hagiwara
  • Method of controlling a pump turbine
    Patent number: 6336322
    Abstract: An object of the present invention is to provide a pump turbine capable of improving the stability of the governor by fully lessening the influences by the S-characteristics even when the running point of the pump turbine is in the S-characteristics region.
    Type: Grant
    Filed: November 8, 2000
    Date of Patent: January 8, 2002
    Assignees: Hitachi, Ltd., The Kansai Electric Power Co., Inc.
    Inventors: Takao Kuwabara, Kei Katayama, Hiroto Nakagawa, Haruki Hagiwara