AIR COMPRESSOR

摘要

PROBLEM TO BE SOLVED: To reduce power consumption during a no-load period and a low load period, in an air compressor having a low pressure stage compressor and a high pressure stage compressor.SOLUTION: An air compressor performing operation in accordance with a consumption air amount of a user side by changing rotation speeds of compressor bodies of a low pressure stage and a high pressure stage comprises: an electric motor 4 rotating and driving a low pressure stage compressor body 1; an inverter 8 for changing a rotation speed of the electric motor; a first air discharge means provided at a discharge side of a high pressure stage compressor body 2; and a control means 18 for controlling the inverter and the first air discharge means. Load operation for changing rotation speeds of the low pressure stage compressor body and the high pressure stage compressor body is performed in a range where the consumption air amount is from the maximum air amount to a determined set air amount. The low pressure stage compressor body and the high pressure stage compressor body are respectively operated at a set lower limit set speed for each of the compressor bodies in no-load operation in which the consumption air amount is zero, and compressed air at the discharge side is discharged from the first air discharge means. The load operation and the no-load operation are repeated when the consumption air amount is equal to or lower than the set air amount.