Turbo compressor and turbo refrigerator provided with same

Abstract

To realize a reduction in cost and extension of the lifespan of a auxiliary bearing which is disposed adjacent to a non-contact bearing supporting a rotor shaft of a centrifugal compressor. A centrifugal compressor ( 2 ) includes: a rotor shaft ( 15 ); an electric motor ( 14 ) provided at an intermediate portion of the rotor shaft ( 15 ) in a coaxial manner with the rotor shaft ( 15 ), the electric motor ( 14 ) being configured to rotationally drive the rotor shaft ( 15 ); an impeller ( 16 ) fixed to one end of the rotor shaft ( 15 ) and forming a refrigerant compressing unit ( 7 ) which compresses a refrigerant; main bearings ( 18 a , 18 b ) formed of non-contact bearings pivotally supporting the rotor shaft ( 15 ) at a portion between the electric motor ( 14 ) and the impeller ( 16 ), and at another end of the rotor shaft ( 15 ); auxiliary bearings ( 19 a , 19 b ) disposed adjacent to the main bearings ( 18 a , 18 b ), the auxiliary bearings being configured to pivotally support the rotor shaft ( 15 ) in place of the main bearings ( 18 a , 18 b ) in a state where functioning of the main bearings ( 18 a , 18 b ) stops; and a lubricating refrigerant supply unit ( 25 ) configured to supply the refrigerant as a lubricant to an inside of the auxiliary bearings ( 19 a , 19 b ) in the state where the functioning of the main bearings ( 18 a , 18 b ) stops.

1 . A centrifugal compressor comprising:
 a rotor shaft;   an electric motor provided at an intermediate portion of the rotor shaft in a coaxial manner with the rotor shaft, the electric motor being configured to rotationally drive the rotor shaft;   an impeller fixed to one end of the rotor shaft and forming a refrigerant compressing unit which compresses a refrigerant;   a non-contact bearing configured to pivotally support the rotor shaft at a portion between the electric motor and the impeller, and a non-contact bearing configured to pivotally support the rotor shaft at another end of the rotor shaft;   an auxiliary bearing disposed adjacent to the non-contact bearing, the auxiliary bearing being configured to pivotally support the rotor shaft in place of the non-contact bearing in a state where functioning of the non-contact bearing stops; and   a lubricating refrigerant supply unit configured to supply the liquid refrigerant as a lubricant to an inside of the auxiliary bearing in the state where the functioning of the non-contact bearing stops.   
     
     
         2 . The centrifugal compressor according to  claim 1 , wherein the lubricating refrigerant supply unit includes:
 a liquid refrigerant storage unit in which the refrigerant in a liquid phase is stored;   a liquid refrigerant supply passage configured to connect the auxiliary bearing and the liquid refrigerant storage unit with each other; and   a solenoid valve connected to the liquid refrigerant supply passage, the solenoid valve being configured to close in an energized state.   
     
     
         3 . The centrifugal compressor according to  claim 2 , wherein the liquid refrigerant storage unit is formed of a bottom portion of a condenser where the refrigerant compressed by the refrigerant compressing unit is to be condensed. 
     
     
         4 . The centrifugal compressor according to  claim 2 , wherein the liquid refrigerant storage unit is formed of a liquid refrigerant jacket for cooling the electric motor, the liquid refrigerant jacket being provided to a casing which houses the electric motor. 
     
     
         5 . The centrifugal compressor according to  claim 2 , wherein the liquid refrigerant storage unit is formed of a pressure applying container which stores the refrigerant in a liquid phase while applying a pressure higher than an ambient pressure of the auxiliary bearing. 
     
     
         6 . The centrifugal compressor according to  claim 1 , wherein the auxiliary bearing is formed of a rolling bearing, and a ceramic material is adopted as a material for forming at least one of an outer race, an inner race, and a rolling element of the auxiliary bearing. 
     
     
         7 . The centrifugal compressor according to  claim 1 , wherein the auxiliary bearing is formed of a rolling bearing, and at least one of an outer race, an inner race, and a rolling element of the auxiliary bearing is coated with a material which allows formation of a lubricating film with lubrication due to a low viscosity fluid. 
     
     
         8 . The centrifugal compressor according to  claim 1 , wherein the auxiliary bearing is formed of a rolling bearing, and at least one of an outer race, an inner race, and a rolling element of the auxiliary bearing is coated with diamond-like carbon. 
     
     
         9 . A centrifugal chiller comprising:
 the centrifugal compressor described in  claim 1 ;   a condenser configured to condense the refrigerant compressed by the centrifugal compressor; and   an evaporator configured to evaporate the refrigerant condensed.