Patents Represented by Law Firm Evenson, McKeown, Edwards & Lenahna, P.L.L.C.
  • Patent number: 5961291
    Abstract: A turbo vacuum pump has a rotor and magnetic bearings. The magnetic bearings are held in a housing having a suction port and an exhaust port, and support the rotor rotatably. A peripheral flow pump stage and screw pump stage are formed in the rotor, so that the pressure at the exhaust port can be at or near atmospheric pressure level. Before starting the turbo vacuum pump, the magnetic bearings are operated to displace a rotor position and to scrape off the reaction products which have deposited inside the pump. In addition, before starting the turbo vacuum pump, a stator of the pump is heated up to decrease a binding force of the reaction products. Therefore, the pump can be restarted, even if the rotor has locked by the solidification of deposited reaction products formed during stopping of the pump.
    Type: Grant
    Filed: September 2, 1997
    Date of Patent: October 5, 1999
    Assignees: Hitachi, Ltd., Seiko Seiki Co., Ltd.
    Inventors: Seiji Sakagami, Masahiro Mase, Chiaki Urano, Shinji Koyano, Yuichi Kinoshita, Takashi Nagaoka, deceased