| 摘要 |
PROBLEM TO BE SOLVED: To provide a multi-stage vacuum pump capable of preventing a burned damage of a motor from an excessive current caused by an increase of a load of a motor in the unsteady state where a pressure in a chamber of a semiconductor manufacturing device or the like is an atmospheric pressure or lower. SOLUTION: The multi-stage type vacuum pump 1 is provided with a housing 2; pump chambers 5, 6, 7, 8 formed in the housing 2 and having different scavenging volume V1, V2, V3, V4; rotors 9, 9', 10, 10', 11, 11', 12, 12'; and rotation shafts 13, 13'. The scavenging volume of the pump chamber at a suction port 3 side is larger than that of the pump chamber at an exhaust port side. The vacuum pump 1 is provided with a motor 17 for rotating/driving the rotation shafts 13, 13'; a detection sensor 26 for detecting the load of the motor 17; and a control device 243 for detecting the load of the motor 17; and a control device 24 for controlling the revolution number of the motor 17 in responsive to a signal 27 from the detection sensor 26. COPYRIGHT: (C)2003,JPO
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