Cryocooler and rotary valve mechanism

A cryocooler comprising:

• a motor;
• a displacer which is engaged to the motor so as to be reciprocated by the motor;
• an expander airtight container in which the displacer is accommodated and a gas expansion chamber is formed between the displacer and the expander airtight container, wherein the expander airtight container includes a low-pressure gas chamber which communicates with a compressor intake port;
• a valve stator which includes a stator plane perpendicular to a valve rotation axis, a high-pressure gas inflow port which is open to the stator plane and communicates with the compressor discharge port, a stator recessed portion which is open to the stator plane and communicates with the gas expansion chamber, and a stator communication path which is open to the stator plane and extends toward the stator recessed portion, wherein the valve stator is disposed in the low-pressure gas chamber;
• and
• a valve rotor which includes a rotor plane which is perpendicular to the valve rotation axis and is in surface-contact with the stator plane, and a rotor recessed portion which is open to the rotor plane and communicates with the high-pressure gas inflow port, wherein the valve rotor is disposed in the low-pressure gas chamber so as to rotate around the valve rotation axis with respect to the valve stator;
• wherein the rotor recessed portion is formed in the valve rotor such that the rotor recessed portion fluidally communicates with the stator recessed portion at a first opening degree at a second phase of a valve rotation, and
• wherein the stator communication path is formed in the valve stator such that the rotor recessed portion fluidally communicates with the stator recessed portion at an opening degree which is smaller than the first opening degree at a first phase of the valve rotation preceding the second phase.

A rotary valve mechanism of a cryocooler, the mechanism comprising:

• a valve stator which includes a stator plane perpendicular to a valve rotation axis and a stator recessed portion which is open to the stator plane and is a portion of a working gas flow path of a cryocooler;
• and
• a valve rotor which includes a rotor plane which is perpendicular to the valve rotation axis and is in surface-contact with the stator plane, and a rotor recessed portion which is open to the rotor plane and is a portion of the working gas flow path of the cryocooler, wherein the valve rotor is disposed so as to rotate around the valve rotation axis with respect to the valve stator,
• wherein the rotor recessed portion is formed in the valve rotor such that the rotor recessed portion fluidally communicates with the stator recessed portion at a first opening degree at a second phase of a valve rotation,
• wherein the valve rotor includes a rotor communication path which is formed in the valve rotor such that the rotor recessed portion fluidally communicates with the stator recessed portion at an opening degree which is smaller than the first opening degree at a first phase of the valve rotation preceding the second phase, and/or
• wherein the valve stator includes a stator communication path which is formed in the valve stator such that the rotor recessed portion fluidally communicates with the stator recessed portion at an opening degree which is smaller than the first opening degree at the first phase of the valve rotation preceding the second phase.