An oil separation member has a partition member that partitions between a discharge chamber and a discharge passage. A circular ring portion is provided in the partition member in a manner extending toward the discharge passage. An introduction hole that communicates the discharge chamber and the discharge passage with each other is formed in the circular ring portion. The introduction hole extends in a tangential direction to the circular ring portion.

A swash plate type variable displacement compressor includes a housing having a suction chamber, a discharge chamber, a swash plate chamber in communication with the suction chamber, a first cylinder block having a plurality of first cylinder bores and a second cylinder block having a plurality of second cylinder bores. The first cylinder bores and the second cylinder bores cooperate to form plural pairs of the first and second cylinder bores. The first cylinder block and the second cylinder block have on outer peripheral side thereof a first projection and a second projection projecting radially, respectively. The first projection and the second projection cooperate together to form an oil separation chamber, an oil reserve chamber, an intermediate pressure chamber and a gas release passage that provides fluid communication between the oil reserve chamber and the intermediate pressure chamber.

To provide a piston compressor capable of preventing excessive oil from accumulating in a crank chamber in any operation state while securing the supply of oil to a swash plate. In a piston compressor in which an oil separation passage (43) is formed in a shaft (7) and a crank chamber (2) communicates with a suction chamber (31) through the oil separation passage (43), a supply passage (40) opens at a region of a cylinder block (1) opposed to a swash plate (18) to thereby allow a working fluid introduced from a discharge chamber (32) into the crank chamber (2) to be supplied to the swash plate (18) and a bypass passage (50) allowing the crank chamber (2) to constantly communicate with the suction chamber (31) is provided to thereby prevent the accumulation of excessive oil in the crank chamber (2) regardless of the operation condition. The bypass passage (50) communicates with the crank chamber (2) at a region positioned in the outer side of a rotation trajectory of the swash plate (18) in the radial direction.

A variable displacement swash plate compressor that includes a cylinder bore, a swash plate chamber, a swash plate, and a double head piston, which defines first and second compression chambers in the cylinder bore. First and second suction chambers are in communication with the first and second compression chambers, respectively. The displacement of the top dead center of the piston in the first compression chamber is greater than the displacement of the top dead center of the piston in the second compression chamber. A first suction passage extends from a suction port to the first suction chamber without passing through the second suction chamber and the swash plate chamber. A second suction passage extends from the first suction chamber to the second suction chamber.

A first bleeding passage 50 configured to allow a crank chamber 2 and a suction chamber 31 to constantly communicate with each other, and a second bleeding passage 60 configured to allow the crank chamber 2 and the suction chamber 31 to constantly communicate with each other are provided. The first bleeding passage 50 is made to communicate with the crank chamber 2 at least via a space (central hole space 54) defined by an insertion end portion of a shaft 7 in a central hole 12 that is formed in the center of a cylinder block 1 and into which the shaft 7 is inserted. The second bleeding passage 60 is opened in an end surface 1a of the cylinder block 1 that is opposed to a swash plate 19.

A variable displacement swash plate type compressor which smoothly supplies oil contained in a refrigerant inside a crank-case to a drive shaft seal region of a front housing, and thus the frictional heat temperature between the drive shaft and a sealing member can be reduced, leakage of refrigerant and pressure is prevented, and durability can be improved.