Air compressor and control method therefor

An air compressor comprising:

• a tank unit storing a compressed air used by a pneumatic tool;
• a compressed air generator which generates the compressed air and supplies the compressed air to the tank unit;
• a motor driving the compressed air generator;
• a drive portion including the motor;
• a controller portion controlling the drive portion;
• and
• a pressure sensor detecting an air pressure of the compressed air in the tank unit,
• wherein the controller portion controls a rotation speed of the motor at multiple levels based on a detection signal P1 of the pressure sensor, a first differential signal which is a differential value d(P1)/dt of the detection signal P1, and a second differential signal obtained by supplying the first differential signal to a low-pass filter.

A control method for an air compressor that includes a tank unit storing an compressed air used by a pneumatic tool, a compressed air generator which generates the compressed air and supplies the compressed air to the tank unit, a motor driving the compressed air generator, a drive portion including the motor, and a controller portion controlling the drive portion, the control method comprising:

• detecting a compressed air pressure P1 in the tank unit;
• detecting a differential signal d(P1)/dt of the pressure P1;
• detecting a differential signal d(P2)/dt of a pressure change signal P2 from which a pulsatory element of the pressure P1 is removed;
• and
• controlling a rotation speed of the motor at multiple levels in accordance with the compressed air pressure P1 and the differential signals d(P1)/dt and d(P2)/dt.