Compressor having check valve and oil separator unit

A compressor comprising:

• a housing having a compression chamber, a discharge chamber, and a suction chamber, a refrigerant being sucked from said suction chamber into said compression chamber and discharged from compression chamber into said discharge chamber;
• a movable member to compress the refrigerant in the compression chamber;
• a discharge passage connecting the discharge chamber to an external refrigerant circuit;
• and
• a suction passage connecting the suction chamber to the external refrigerant circuit;
• wherein a check valve preventing reverse flow of the refrigerant from said external refrigerant circuit to said discharge chamber, an oil separator separating a mist of lubricating oil contained in the refrigerant from the refrigerant, and an oil passage introducing the separated lubricating oil into a low pressure region in the compressor, are provided in said discharge chamber or said discharge passage.