PURPOSE: To improve the vibration characteristic, stability and pump performance by forming an impeller shaft and an electric motor rotor for driving said shaft into an integral rotating shaft, supporting the both end parts of the rotating shaft by magnetic bearings, and cooling the rotating shaft.
CONSTITUTION: A multistage impeller shaft 5 and a casing surrounding the impeller 5 to form a fluid passage are provided in the inside of a housing 3 having a suction port 1 and exhaust port 7 formed thereon. In this case, the impeller 5 and an electric motor rotor 9 are formed into an integral rotating shaft 6. Radial magnetic bearings 2, 2' are provided between the both end parts of the rotating shaft 6 and the housing 3, respectively, and also a thrust magnetic bearing 10 is provided near the bearing 2'. The electric motor rotor 9 in the rotating shaft 6 has a hollow part 6a formed between them, and a coolant feed conduit 11 is provided in the inside so as not to touch the hollow part 6a.
FUSAYASU YOSHIHIDE
FURUYA YASUSHI
EBARA RES CO LTD