Turbo vacuum pump with a magnetically levitated rotor and a control unit for displacing the rotator at various angles to scrape deposits from the inside of the pump

A turbo vacuum pump comprising:

• a housing having a suction port and an exhaust port;
• a stator retained in said housing;
• magnetic bearings mounted in said housing;
• a rotary shaft supported rotatably by said magnetic bearings;
• a drive unit which rotates said rotary shaft;
• a magnetic bearing control unit which rotates said magnetic bearings, whereby a gas sucked from said suction port is compressed and exhausted to the atmosphere from said exhaust port;
• a stator heating control unit which controls a heating of said stator to a predetermined temperature range prior to starting said vacuum pump;
• a first sensor which detects RPM of said rotary shaft;
• a second sensor which detects an acceleration time of said rotary shaft;
• and
• a controller which controls starting and stopping of said magnetic bearing control unit and said drive unit based on detected values of said first and second sensors.

A method of running a turbo vacuum pump for exhausting to the atmosphere, which pump has a rotary shaft supported rotatably by magnetic bearings, said method comprising:

• detecting magnitude of a motor current value and a consumed electric power of said motor at a time of starting rotation of said turbo vacuum pump;
• stopping rotation of said rotary shaft if at least one of said current and said power is over a predetermined value;
• and
• causing said magnetic bearings to displace said rotary shaft a predetermined number of times.

A method of running a turbo vacuum pump for exhausting to the atmosphere, which pump has a rotary shaft supported rotatably by magnetic bearings, said method comprising:

• detecting a rate of increase of RPM of said rotary shaft at the time of starting rotation of said turbo vacuum pump;
• stopping rotation of said rotary shaft if said rate of increase is below a predetermined value;
• and
• causing said magnetic bearings to displace said rotary shaft a predetermined number of times.

A turbo vacuum pump comprising:

• a housing having a suction port and an exhaust port;
• a stator retained in said housing;
• magnetic bearings mounted in said housing;
• a rotary shaft supported rotatably by said magnetic bearings;
• a drive unit which drives the rotary shaft;
• a control unit which controls the magnetic bearings, whereby a gas sucked from said suction port is compressed and exhausted to the atmosphere from said exhaust port;
• a centrifugal compression pump impeller and a multistage peripheral flow impeller provided on said rotary shaft, sequentially from the side of said suction port, whereby said stator forms a multistage peripheral flow compression pump stage together with said peripheral flow impeller;
• a first sensor which detects RPM of said rotary shaft;
• a second sensor which detects an abnormality of said rotary shaft;
• a heating unit which heats said stator;
• a first controller or displacing said rotary shaft by a predetermined amount based on detected values of said first and second sensors;
• and
• a second controller which controls heating of said stator by said heating means, to a temperature ranging from 100.degree. C. to 180.degree. C.

A turbo vacuum pump comprising:

• a housing having a suction port and an exhaust port;
• a stator retained in said housing;
• magnetic bearings mounted in said housing;
• a rotary shaft supported rotatably by said magnetic bearings;
• a drive unit which rotates said rotary shaft;
• a first control unit which controls said magnetic bearings, so that a gas sucked from said suction port is compressed and exhausted to the atmosphere from said exhaust port;
• a stator heating control unit which controls a heating of said stator to a predetermined temperature range prior to starting said vacuum pump;
• a first sensor which detects RPM of said rotary shaft;
• and
• a second sensor which detects at least one of electric current and power of said drive unit;
• wherein said first control unit provides said magnetic bearings with a command for displacing said rotary shaft by a predetermined amount, if the detected value of said second sensor exceeds a predetermined value when said first sensor detects a standstill of said rotary shaft.