Cryocooler and flow path switching mechanism of cryocooler

A flow path switching mechanism of a cryocooler, in which the cryocooler includes a cold head including a displacer movable in an axial direction, a drive piston connected to the displacer to move the displacer in the axial direction, an expansion chamber being formed with the displacer, and a piston drive chamber being formed with the drive piston, the drive piston being driven in the axial direction by a pressure difference between the piston drive chamber and the expansion chamber,

• the flow path switching mechanism comprising:
• a spool valve including a valve drive chamber and a spool that moves between a first position and a second position in response to a pressure of the valve drive chamber, the spool connecting the expansion chamber to a compressor discharge port at the first position, the spool connecting the expansion chamber to a compressor suction port at the second position, and the spool reciprocating between the first position and the second position to generate a periodic pressure fluctuation in the expansion chamber;
• and
• a pressure control mechanism configured to control a pressure of the valve drive chamber so that the spool reciprocates between the first position and the second position, and to generate a pressure fluctuation having an opposite phase to the pressure fluctuation in the expansion chamber in the piston drive chamber in synchronization with the reciprocation of the spool.