Centrifugal compressor

A centrifugal compressor comprising:

• an electric motor coupled to a low-speed shaft;
• an impeller;
• and
• a speed increaser including:
• a ring member including a circumferential wall and configured to be rotated when the low-speed shaft rotates,
• a high-speed shaft located at an inner side of the circumferential wall and coupled to the impeller,
• a plurality of rollers located between the circumferential wall and the high-speed shaft,
• a speed increaser housing member including a tubular main body that accommodates the ring member, part of the high-speed shaft, and the rollers and stores oil so that a lower portion of the ring member is immersed in the oil,
• a discharge passage configured to discharge the oil out of the ring member,
• a partition located between an inner circumferential surface of the main body and the lower portion of the ring member in a radial direction of the circumferential wall,
• a reservoir region, in which the oil is reserved, defined between the partition and the inner circumferential surface of the main body,
• an agitation region, in which the oil is agitated by the ring member, defined between the partition and the lower portion of the ring member,
• a communication passage for discharging the oil in the agitation region to the reservoir region, and
• an oil passage having an opening that opens in the inner circumferential surface of the main body so as to communicate with the reservoir region, wherein
• the agitation region has a first end in the axial direction of the circumferential wall that communicates with the discharge passage, and a second end in the axial direction that communicates with the communication passage,
• the opening of the oil passage is located at a position closer to the discharge passage than the communication passage in the axial direction, and
• power is transmitted from the low-speed shaft to the high-speed shaft by the ring member and the rollers.