Oil separator and refrigeration cycle apparatus

An oil separator, comprising:

• a first pipe connected to a discharge port of a compressor;
• a second pipe connected to a suction port of the compressor;
• a differential pressure generation mechanism that has
• a third pipe that connects the first pipe and the second pipe with each other and
• a filter portion located at a distal end of the third pipe at which the third pipe is connected to the first pipe,
• the differential pressure generation mechanism being configured to generate a differential pressure between a pressure of high-pressure refrigerant that flows in the first pipe and a pressure of low-pressure refrigerant that flows in the second pipe;
• and
• an oil return mechanism that has
• an oil return port opened and formed at the first pipe and disposed downstream of a connection position at which the third pipe is connected to the first pipe and
• a portion of an oil return circuit that connects the first pipe and the second pipe with each other via the oil return port,
• the oil return mechanism being configured to return, via the oil return port and the oil return circuit, lubricating oil included in the high-pressure refrigerant from the first pipe to the second pipe,
• the filter portion in the differential pressure generation mechanism being configured to collect, by the differential pressure, the lubricating oil that is in a form of mist included in the high-pressure refrigerant, and
• the first pipe allowing the collected lubricating oil to move downstream along an internal wall of the first pipe.