Centrifugal compressor

Abstract

A centrifugal compressor includes a motor cooling passage through which cooling fluid for cooling an electric motor flows, an air passage through which cooling air for cooling a first air bearing and a second air bearing is supplied to each of the first air bearing and the second air bearing, and a heat exchanger cooling the cooling air. The motor cooling passage includes a plurality of cooling axial passages having a first cooling axial passage through which the cooling fluid is supplied to the heat exchanger and a second cooling axial passage through which the cooling fluid is discharged from the heat exchanger. The heat exchanger has a first port communicating with the first cooling axial passage, a second port communicating with the second cooling axial passage, and a third port communicating with an air axial passage extending in an axial direction of a rotary shaft.

What is claimed is: 
     
         1 . A centrifugal compressor comprising:
 a rotary shaft;   an electric motor that drives the rotary shaft;   a compressor impeller that is rotated together with the rotary shaft to compress fluid;   a housing including a motor chamber that accommodates the electric motor;   a first air bearing and a second air bearing disposed on opposite sides of the electric motor in an axial direction of the rotary shaft to rotatably support the rotary shaft;   a motor cooling passage through which cooling fluid for cooling the electric motor flows;   an air passage through which cooling air for cooling the first air bearing and the second air bearing is supplied to each of the first air bearing and the second air bearing; and   a heat exchanger configured to cool the cooling air by heat exchange between the cooling air and the cooling fluid,   the housing having a circumferential wall that surrounds the electric motor and has openings on opposite ends, a first end wall that closes one of the openings of the circumferential wall and holds the first air bearing, and a second end wall that closes the other of the openings of the circumferential wall and holds the second air bearing,   the motor chamber being defined by the circumferential wall, the first end wall, and the second end wall,   the motor cooling passage including a plurality of cooling axial passages extending in the axial direction of the rotary shaft and spaced from each other along a circumferential direction of the circumferential wall,   the cooling axial passages adjacent to each other along the circumferential direction of the circumferential wall being connected, in the motor cooling passage formed in the housing, wherein   the plurality of cooling axial passages includes a first cooling axial passage through which the cooling fluid is supplied to the heat exchanger and a second cooling axial passage through which the cooling fluid is discharged from the heat exchanger,   the air passage has an air axial passage being positioned between the first cooling axial passage and the second cooling axial passage in the housing and extending in the axial direction of the rotary shaft toward each of the first end wall and the second end wall, and an air radial passage that communicates with the air axial passage and through which the cooling air is supplied to the first air bearing and the second air bearing,   the heat exchanger has a first port communicating with the first cooling axial passage, a second port communicating with the second cooling axial passage, and a third port communicating with the air axial passage, and   the heat exchanger is attached to the housing such that the first port, the second port, and the third port overlap the first cooling axial passage, the second cooling axial passage, and the air axial passage, respectively, on an outer side of the housing in a radial direction of the rotary shaft.   
     
     
         2 . The centrifugal compressor according to  claim 1 , wherein
 the motor cooling passage includes:
 a cooling fluid discharge passage to which the cooling fluid is discharged from the first cooling axial passage; and 
 a cooling fluid supply passage through which the cooling fluid is supplied to the second cooling axial passage, 
   the air passage includes an air supply passage through which the cooling air is supplied to the air axial passage,   a part of an outer peripheral surface of the circumferential wall is an attaching surface to which the heat exchanger is attached,   the cooling fluid supply passage, the cooling fluid discharge passage, and the air supply passage are opened at the attaching surface,   the heat exchanger has an attachment surface to be attached to the attaching surface of the housing, and   the first port communicating with the cooling fluid discharge passage, the second port communicating with the cooling fluid supply passage, and the third port communicating with the air supply passage are opened at the attachment surface of the heat exchanger.   
     
     
         3 . The centrifugal compressor according to  claim 2 , wherein
 the cooling air passing through the heat exchanger corresponds to a part of air compressed by the compressor impeller,   the housing has an air branch passage that is opened at the attaching surface of the housing and through which a part of the air compressed by the compressor impeller flows, and   a fourth port is further opened at the attachment surface of the heat exchanger and communicates with the air branch passage.