Centrifugal compressor

Abstract

A centrifugal compressor includes a rotary shaft, an electric motor, which has a rotor, a tubular boss, through which the rotary shaft extends, and a radial bearing. The rotor has a rotor end face, which is an end face in an axial direction of the rotary shaft. The boss has a boss end face, which is an end face in the axial direction of the rotary shaft. The rotor end face and the boss end face face each other in the axial direction of the rotary shaft. A thrust bearing is arranged between the rotor end face and the boss end face to receive thrust force generated by rotation of the impeller.

1 . A centrifugal compressor comprising:
 a rotary shaft;   an electric motor, which includes a rotor attached to the rotary shaft and rotates the rotary shaft;   an impeller, which rotates as the rotary shaft rotates, thereby compressing fluid;   a housing, which accommodates the rotary shaft, the electric motor, and the impeller;   a tubular boss, which is provided in the housing and through which the rotary shaft extends; and   a radial bearing, which is provided between the boss and the rotary shaft and rotationally supports the rotary shaft, wherein   the rotor has a rotor end face, which is an end face in an axial direction of the rotary shaft,   the boss has a boss end face, which is an end face in the axial direction of the rotary shaft,   the rotor end face and the boss end face face each other in the axial direction of the rotary shaft, and   the centrifugal compressor comprises a thrust bearing, which is arranged between the rotor end face and the boss end face and receives thrust force generated by rotation of the impeller.   
     
     
         2 . The centrifugal compressor according to  claim 1 , wherein
 the boss is a first boss,   the centrifugal compressor further comprises a second boss, which makes a pair with the first boss,   the first boss and the second boss are arranged to face each other in the axial direction of the rotary shaft with the rotor in between,   the rotor has a first rotor end face as the rotor end face and a second rotor end face, which is located on a side opposite to the first rotor end face in the axial direction of the rotary shaft,   the first boss has a first boss end face as the boss end face, the first boss end face and the first rotor end face facing each other in the axial direction of the rotary shaft,   the second boss has a second boss end face as the boss end face, the second boss end face and the second rotor end face facing each other in the axial direction of the rotary shaft,   the thrust bearing is a first thrust bearing provided between the first rotor end face and the first boss end face, and   the centrifugal compressor further comprises a second thrust bearing provided between the second rotor end face and the second boss end face.   
     
     
         3 . The centrifugal compressor according to  claim 2 , wherein the rotor includes
 a plurality of magnetic steel sheets, which is laminated in the axial direction of the rotary shaft,   first and second holding plates, which hold the magnetic steel sheets in between in the axial direction of the rotary shaft,   a rivet, which includes a barrel and first and second heads, wherein the barrel is inserted through the magnetic steel sheets and the first and second holding plates, and the first and second heads have a diameter greater than that of the barrel and are arranged at opposite ends of the barrel in the axial direction of the rotary shaft,   a first spacer, which has a first contact surface contacting a plate surface of the first holding plate, the first rotor end face, which is arranged on a side opposite to the first contact surface, and a first accommodating portion, which accommodates the first head, and   a second spacer, which has a second contact surface contacting a plate surface of the second holding plate, the second rotor end face, which is arranged on a side opposite to the second contact surface, and a second accommodating portion, which accommodates the second head.   
     
     
         4 . The centrifugal compressor according to  claim 3 , wherein
 the first thrust bearing is a non-contact type hydrodynamic bearing, which receives the thrust force in a non-contact state in which hydrodynamic pressure generated by rotation of the rotor creates a clearance between the first thrust bearing and the first rotor end face,   the second thrust bearing is a non-contact type hydrodynamic bearing, which receives the thrust force in a non-contact state in which hydrodynamic pressure generated by rotation of the rotor creates a clearance between the second thrust bearing and the second rotor end face, and   the first rotor end face and the second rotor end face are smoother than the plate surfaces of the first and second holding plates.   
     
     
         5 . The centrifugal compressor according to  claim 1 , wherein the thrust bearing includes
 a thrust top foil, which is arranged between the boss end face and the rotor end face at a position closer to the rotor end face than to the boss end face and supports the rotor in a non-contact state when the rotary shaft rotates, and   a thrust bump foil, which is arranged between the boss end face and the rotor end face at a position closer to the boss end face than to the rotor end face and is elastically deformed to support the thrust top foil in a displaceable manner in the axial direction of the rotary shaft.   
     
     
         6 . The centrifugal compressor according to  claim 5 , wherein the radial bearing includes
 a radial top foil, which is arranged outward of an outer circumferential surface of the rotary shaft in a radial direction of the rotary shaft and supports the rotary shaft in a non-contact state when the rotary shaft rotates, and   a radial bump foil, which is arranged outward of the radial top foil in the radial direction of the rotary shaft and elastically supports the radial top foil, wherein   the thrust bearing has a shape of a loop having an inner diameter longer than a diameter of the rotary shaft,   a space is provided inward of the thrust bearing in the radial direction of the rotary shaft, and   the space causes a radial clearance, which is provided between the radial top foil and the radial bump foil, and a thrust clearance, which is provided between the thrust top foil and the thrust bump foil, to communicate with each other.   
     
     
         7 . The centrifugal compressor according to  claim 1 , further comprising:
 a drive circuit, which drives the electric motor; and   a circuit case, which defines a circuit chamber that accommodates the drive circuit and is attached to the housing from the axial direction of the rotary shaft, wherein   the housing includes
 a motor chamber, which accommodates the electric motor and into which fluid is drawn, and 
 a partition wall, which partitions the motor chamber and the circuit chamber from each other, and 
   the drive circuit exchanges heat with the fluid in the motor chamber via the partition wall.   
     
     
         8 . The centrifugal compressor according to  claim 6 , wherein an inner edge of the thrust bearing protrudes further inward than an inner circumferential surface of the boss in the radial direction of the rotary shaft.