MULTI-STAGE COMPRESSOR

摘要

Provided is a multi-stage compressor which can surely prevent a liquid compression by a compression mechanism of the higher stage side and prevent lowering of compression efficiency by overheat of an injection coolant and hoisting of a lubricant by the injection coolant. The multi-stage compressor branches an injection circuit (40) into a plurality of circuits. The multi-stage compressor communicably connects its first circuit (41) to a space in a sealed housing (2) of the same side as the higher-stage side compression mechanism (4) with respect to an electric motor (5) and communicably connects its second circuit (42) to a space in the sealed housing (2) at the opposite side of the higher-stage side compression mechanism (4) so as to sandwich the electric motor (5). The multi-stage compressor includes a switching mechanism (43) which switches the injection circuit (40) to the first circuit (41) or the second circuit (42) in accordance with the dry degree of the injection coolant.