Patent ID: 8784067

Claim:
A scroll type booster comprising: a scroll type compression unit which sucks a pressurized fluid supplied from an external pressurized fluid supply unit through an intake port, compresses the pressurized fluid in a compressor chamber, and discharges a compressed fluid from a discharge port during an orbiting movement with wrap portions of two scroll members overlapped; a drive unit for driving at least one of the scroll members which form the compression unit for the orbiting movement; an on-off valve disposed between the intake port of the compression unit and the pressurized fluid supply unit for allowing and blocking a communication between the intake port and the pressurized fluid supply unit; a discharge pressure sensor disposed at a discharge side of the compression unit; an intake pressure sensor disposed at an intake side of the compression unit; and a control unit for controlling opening and closing of the on-off valve, and driving and stopping of the drive unit, wherein the control unit allows the drive unit to start driving said at least one of the scroll members for the orbiting movement when a difference between a pressure detected by the discharge pressure sensor and a pressure detected by the intake pressure sensor becomes no more than a predetermined differential pressure after opening the on-off valve to allow the external pressurized fluid supply unit to communicate with the intake port, so that the pressurized fluid is supplied from the external pressurized fluid supply unit to the intake port to increase the pressure detected by the intake pressure sensor and to press the one of the two scroll members in the axial direction to decrease a gap formed between the two scroll members.