Piston type compressor

A piston-type compressor comprising:

• a housing having a shaft hole and a plurality of cylinder bores provided around the shaft hole;
• a drive shaft inserted and rotationally supported in the shaft hole;
• a plurality of pistons inserted in respective cylinder bores of the plurality of cylinder bores, wherein the pistons are caused to reciprocate within the respective cylinder bores by a rotation of the drive shaft;
• a plurality of communication passages providing a communication between the plurality of cylinder bores and the shaft hole;
• a valve mechanism arranged to operate integrally with the drive shaft in the shaft hole and including a residual gas bypass passage in communication with the plurality of communication passages to guide a residual gas in one cylinder bore of the plurality of cylinder bores to a second cylinder bore of the plurality of cylinder bores;
• a communication hole formed inside the drive shaft;
• and
• a cylindrical body inserted in the communication hole to disconnect the residual gas bypass passage and the communication hole from each other and to open an interior space of the cylindrical body to the communication hole, wherein
• the valve mechanism includes
• an annular space defined outside the cylindrical body in the communication hole, wherein the annular space extends around an entire circumference of the cylindrical body, and
• a plurality of connection holes providing communication between the annular space and the communication passages, and
• the residual gas bypass passage comprises the annular space and the connection holes.