Scroll compressor having recessed outer fixed scroll wall

1. A scroll compressor comprising:

a housing having a suction port and a discharge port; and

a compression mechanism accommodated in the housing, wherein the compression mechanism is configured to compress fluid drawn in from the suction port and discharge the fluid out of the discharge port, wherein

the housing includes:

a first housing member having an annular partition wall, and

a second housing member fastened to the first housing member by a fastener, wherein the first housing member and the second housing member internally define a space,

the annular partition wall includes a fastened portion through which the fastener is inserted, wherein the fastened portion is thicker than other portions in a circumferential direction of the partition wall,

the fastened portion protrudes inward in a radial direction in the space, the compression mechanism includes:

a fixed scroll member accommodated in the space, and

an orbiting scroll member accommodated in the space, wherein the orbiting scroll member is engaged with the fixed scroll member to define a compression chamber,

the fixed scroll member includes:

a fixed spiral wall extending spirally, and

an outer circumferential wall that surrounds the fixed spiral wall,

the outer circumferential wall includes a recess recessed inward in the radial direction, wherein the recess is located at a part of the outer circumferential wall opposed to the fastened portion in the radial direction,

a dimension of the recess in the circumferential direction is greater than a dimension of a part of the fastened portion in the circumferential direction that protrudes into the space;

the recess extends from a distal end of a first side of the outer circumferential wall toward a basal end of a second side of the outer circumferential wall,

the recess includes a basal recess located on the second side of the outer circumferential wall, and a distal recess located on the first side of the outer circumferential wall, and a communication passage that opens in the distal recess and causes an outer side and an inner side of the outer circumferential wall to communicate with each other,

the distal recess is deeper in the radial direction than the basal recess, and

a part of the fastened portion is in the recess.

2. The scroll compressor according to claim 1 , wherein

the fastened portion comprises a plurality of fastened portions arranged in the circumferential direction of the annular partition wall of the first housing member, and

the recess is arranged in correspondence with at least one of the plurality of fastened portions.

3. The scroll compressor according to claim 1 , wherein

the fastened portion comprises a plurality of fastened portions arranged in the circumferential direction of the annular partition wail of the first housing member,

the recess comprises a plurality of recesses, where at least two of the plurality of recesses correspond with a respective at least two of the plurality of fastened portions, and

the communication passage comprises a plurality of communication passages, a respective communication passage of the plurality of communication passages being formed in at least two of the plurality of recesses.

4. The scroll compressor according to claim 1 , wherein

the fastened portion comprises a plurality of fastened portions incorporated in the first housing member,

the recess comprises a plurality of recesses of the outer circumferential wall, the plurality of recesses being opposed to the respective plurality of fastened portions, and

at least parts of the outer circumferential wall do not include the recess.