Patent ID: 7523620

Claim:
A displacement control mechanism for a variable displacement compressor that compresses refrigerant in a suction pressure zone and delivers the compressed refrigerant to a discharge pressure zone, the compressor includes a control pressure chamber, a supply passage that connects the discharge pressure zone to the control pressure chamber, and a delivery passage that connects the suction pressure zone to the control pressure chamber, the displacement control mechanism permits refrigerant in the discharge pressure zone to be supplied to the control pressure chamber through the supply passage and permits refrigerant in the control pressure chamber to be delivered to the suction pressure zone through the delivery passage, thereby adjusting the pressure in the control pressure chamber to control the displacement of the compressor, the displacement control mechanism comprising: a valve hole forming part of the supply passage or the delivery passage; a valve body for opening and closing the valve hole; a pressure sensing device that urges the valve body with a force that corresponds to a pressure difference between a first position and a second position, said first and second positions being located in the discharge pressure zone; and a displacing device configured to displace the valve body, when a pressure in the suction pressure zone falls below a predetermined reference pressure, the displacing device being further configured to displace the valve body in a direction increasing the opening degree of the valve hole with the driving force, when the valve forms part of the supply passage, and the displacing device being further configured to displace the valve body in a direction reducing the opening degree of the valve hole with the driving force, when the valve hole forms part of the delivery passage.