Method for manufacturing compressor casing, casing blank, and compressor casing

A casing blank comprising:

• a first cylindrical part which has a cylindrical shape around an axis, and which internally defines a motor housing space;
• a second cylindrical part which has a cylindrical shape around the axis, which internally defines a compression unit housing space having a smaller diameter than the motor housing space, and which is connected to one side of the first cylindrical part and positioned on one side in an axial direction along the axis than the cylindrical part;
• and
• an annular part which protrudes inward in a radial direction from an inner peripheral surface of a boundary portion between the first cylindrical part and the second cylindrical part, and which includes a recessed portion recessed toward the one side in the axial direction from a first surface facing the other side in the axial direction, wherein an end of the recessed portion on the one side in the axial direction is closed by a second surface of the annular part facing the one side and the compression unit housing space in the axial direction, and the recessed portion does not communicate with the compression unit housing space,
• wherein a portion of a side surface of the recessed portion is located outward in the radial direction from an inner peripheral surface of the second cylindrical part, and
• wherein the recessed portion and the annular part are integrally formed, and
• the recessed portion serves as a flow path which causes the motor housing space and the compression unit housing space to communicate with each other by machining an inner peripheral surface of the second cylindrical part that extends toward the one side in the axial direction from an outer end in the radial direction of the second surface of the annular part and the second surface of the annular part facing the one side in the axial direction.

A compressor casing comprising:

• a first cylindrical part which has a cylindrical shape around an axis, and which internally defines a motor housing space;
• a second cylindrical part which has a cylindrical shape around the axis, which internally defines a compression unit housing space having a smaller diameter than the motor housing space, and which is connected to the first cylindrical part and positioned on one side in an axial direction along the axis than the first cylindrical part;
• and
• an annular part which protrudes inward in a radial direction from an inner side of a boundary portion between the first cylindrical part and the second cylindrical part, and which includes a flow path that causes the motor housing space and the compression unit housing space to communicate with each other,
• wherein the flow path is formed in such a way that a recessed portion integrally formed in the annular part is caused to communicate with the compression unit housing space by machining a surface of the annular part facing the one side and the compression unit housing space in the axial direction and an inner peripheral surface of the second cylindrical part before the machining that extends toward the one side in the axial direction from an outer end in the radial direction of the surface of the annular part,
• wherein an end of the recessed portion on the one side in the axial direction is closed by, the surface of the annular part, and the recessed portion does not communicate with the compression unit housing space, and
• wherein a portion of an inner peripheral surface of the flow path is located outward in the radial direction from the inner peripheral surface of the second cylindrical part before the machining is performed.