Centrifugal compressor

A centrifugal compressor, comprising:

• a low speed shaft that is rotated by a drive source;
• an impeller that is attached to a high speed shaft, which rotates at a speed higher than a speed of the low speed shaft;
• a speed increaser that transmits power of the low speed shaft to the high speed shaft;
• a housing that includes
• a drive source chamber that accommodates the drive source,
• an impeller chamber that accommodates the impeller,
• a speed increaser chamber that accommodates the speed increaser, and
• a dividing wall having an insertion hole through which the high speed shaft is passed, the dividing wall dividing the impeller chamber and the speed increaser chamber from each other;
• a seal member provided between an outer circumferential surface of the high speed shaft and an inner circumferential surface of the insertion hole;
• an oil pan that stores oil supplied to the speed increaser via an oil passage;
• and
• a pressure relief passage that connects an upper part of the oil pan to a pressure relief hole that opens in an outer portion of the housing, wherein
• the pressure relief passage includes a first pressure relief passage and a detouring pressure relief passage,
• the pressure relief hole is arranged above the first pressure relief passage in a direction of gravitational force,
• the detouring pressure relief passage includes a detouring pressure relief passage that extends, in a detouring manner, from a lower part of the first pressure relief passage to a region located in an upper part, and
• a minimum cross-sectional flow area of the detouring pressure relief passage is smaller than a minimum cross-sectional flow area of the first pressure relief passage.