Scroll compressor having injection passage containing muffler

A scroll compressor, comprising:

• a housing including a suction port into which refrigerant is drawn and a discharge port out of which the refrigerant is discharged;
• a rotary shaft accommodated in the housing and supported by the housing to be rotatable about a rotation axis;
• and
• a compression mechanism accommodated in the housing, the compression mechanism including a fixed scroll fixed to the housing and a movable scroll configured to orbit as the rotary shaft rotates, wherein
• the compression mechanism includes a compression chamber configured to compress the refrigerant drawn when the fixed scroll meshes with the movable scroll,
• the housing includes an intermediate pressure chamber into which refrigerant having an intermediate pressure is introduced from an external refrigerant circuit, the intermediate pressure being higher than a suction pressure of the refrigerant drawn into the compression chamber and lower than a discharge pressure of the refrigerant discharged from the compression chamber,
• the intermediate pressure chamber and the compression chamber in a process of compression are connected to each other by an injection passage, and
• the injection passage includes a muffler.