Patent ID: 8328524

Claim:
An air compressor, comprising: a tank portion for reserving compressed air to be used in a pneumatic tool; a compressed air generation portion for generating compressed air and supplying said compressed air to said tank portion; a drive portion comprising a motor for driving said compressed air generation portion; a pressure sensor for detecting an internal pressure P of said tank portion; and a control circuit portion for controlling said drive portion, the control circuit portion comprising: first means for storing a plurality of values indicating different rotational speeds of the motor; second means for calculating a rate ΔP/ΔT of change of the internal pressure ΔP with respect to a change in time ΔT; and third means for selecting one of the values based on the internal pressure P and the rate ΔP/ΔT of change of the internal pressure, and controlling the rotational speed of said motor in accordance with the selected value.