Patents by Inventor Seiji Tsuru

Seiji Tsuru 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).

  • Operation control system of rotary displacement type vacuum pump
    Patent number: 4664601
    Abstract: An operation control system of a rotary displacement type vacuum pump capable of reducing a starting torque of the vacuum pump includes a suction regulating valve and a pressure sensor for monitoring suction pressure located in a suction passage of the vacuum pump, an inverter electrically coupled to a variable speed electric motor for driving the vacuum pump and a control unit. The control unit is operative, when the vacuum pump is started, to keep the suction regulating valve in a closed position until the value of suction pressure monitored by the pressure sensor reaches a predetermined upper limit value and to gradually increase the rpm. of the variable speed electric motor. The control unit is further operative to produce a signal for increasing or decreasing the rpm of the variable speed electric motor so as to bring the value of suction pressure monitored by the pressure sensor to the vicinity of a predetermined lower limit value.
    Type: Grant
    Filed: July 23, 1985
    Date of Patent: May 12, 1987
    Assignee: Hitachi, Ltd.
    Inventors: Riichi Uchida, Katsumi Matsubara, Seiji Tsuru