Piston type variable displacement compressor

A compressor comprising a swash plate mounted on a drive shaft for integral rotation therewith in a crank chamber and a piston coupled to the swash plate and disposed in a cylinder bore, wherein the rotation of the drive shaft is converted to a reciprocating movement of the piston to compress gas supplied to the cylinder bore from an external circuit by way of a suction chamber and to discharge the gas to a discharge chamber, said swash plate being tiltable between a maximum inclining angle and a minimum inclining angle with respect to the drive shaft according to the difference between pressure in the crank chamber and the suction chamber to control a displacement of the compressor, a supply passage for connecting the discharge chamber with the crank chamber, said supply passage being selectively opened and closed in accordance with an operational status of the compressor, wherein said swash plate is inclined toward the minimum inclining angle by the pressure supplied to the crank chamber from the discharge chamber when the supply passage is opened and the swash plate is inclined toward the maximum inclining angle when the supply passage is closed;

• said compressor further comprising:
• means for disconnecting the external circuit with the suction chamber when the swash plate is at the minimum inclining angle;
• a valve for selectively opening and closing the supply passage in accordance with the operational status of the compressor;
• a pressure decreasing passage means connecting the crank chamber and the suction chamber for decreasing the pressure in the crank chamber, said pressure decreasing passage means being arranged to release the pressure in the crank chamber to the suction chamber when the pressure in the crank chamber is greater than the pressure in the suction chamber, whereby the swash plate is inclined toward the maximum inclining angle;
• and
• means for adjusting the flow in the pressure decreasing passage means, such that the pressure decreasing passage means is opened to a greater degree when the swash plate is at the maximum inclining angle than when the swash plate is between the maximum and minimum inclining angles.

A compressor comprising a swash plate mounted on a drive shaft for integral rotation therewith in a crank chamber and a piston coupled to the swash plate and disposed in a cylinder bore, wherein the rotation of the drive shaft is converted to a reciprocating movement of the piston to compress gas supplied to the cylinder bore from an external circuit by way of a suction chamber and to discharge the gas to a discharge chamber, said swash plate being tiltable between a maximum inclining angle and a minimum inclining angle with respect to the drive shaft according to the difference between pressures in the crank chamber and the suction chamber, and wherein said swash plate controls the displacement of the compressor to be maximum when the swash plate is at the maximum inclining angle and to be minimum when the swash plate is at the minimum inclining angle, said compressor further comprising:

• means for disconnecting the external circuit with the suction chamber when the swash plate is at the minimum inclining angle;
• a pressure decreasing passage means connecting the crank chamber and the suction chamber for decreasing the pressure in the crank chamber, said pressure decreasing passage means being arranged to release the pressure in the crank chamber to the suction chamber when the pressure in the crank chamber is greater than the pressure in the suction chamber, whereby the swash plate is inclined toward the maximum inclining angle;
• a gas supply passage connecting the discharge chamber with the crank chamber;
• a valve for selectively opening and closing the supply passage, wherein the swash plate is inclined toward the minimum inclining angle when the supply passage is opened, and wherein the swash plate is inclined toward the maximum inclining angle when the supply passage is closed;
• a circulating passage means including the pressure decreasing passage means and the supply passage, said circulating passage being selectively opened and closed such that gas circulates in the circulating passage at selected times;
• and
• means for adjusting the flow in the pressure decreasing passage means, wherein the pressure decreasing passage means is opened to a greater degree when the swash plate is at the maximum inclining angle than when the swash plate is between the maximum and minimum inclining angles.