GM cryocooler

A GM cryocooler comprising:

• a valve rotor that comprises:
• a high pressure flow path, the high pressure flow path is disposed in the valve rotor and opens to a rotor plane of the valve rotor,
• a low pressure flow path, the low pressure flow path is disposed in the valve rotor and opens to the rotor plane of the valve rotor, and
• a pressure equalization flow path, the pressure equalization flow path is disposed in the valve rotor and opens to the rotor plane of the valve rotor;
• and
• a valve group that comprises:
• a first intake valve that is configured to intake a working gas into a first gas chamber, the high pressure flow path is a portion of the first intake valve,
• a first exhaust valve that is configured to exhaust the working gas from within the first gas chamber, the low pressure flow path is a portion of the first exhaust valve,
• a second intake valve that is configured to intake the working gas into a second gas chamber, the high pressure flow path is a portion of the second intake valve,
• a second exhaust valve that is configured to exhaust the working gas from within the second gas chamber, the low pressure flow path is a portion of the second exhaust valve, and
• a pressure equalizing valve that is configured to perform pressure equalization between the first gas chamber and the second gas chamber, the pressure equalization flow path is a portion of the pressure equalizing valve,
• wherein:
• the high pressure flow path is configured to always be physically connected to a discharge port of a compressor,
• the low pressure flow path is configured to always be physically connected to a suction port of the compressor and to be open on a side opposite to the high pressure flow path in a radial direction on the rotor plane,
• the pressure equalization flow path is a hollow portion which extends inside the valve rotor in a valve radial direction, and defines a first pressure equalization flow path contour and a second pressure equalization flow path contour on the rotor plane,
• the first pressure equalization flow path contour is positioned between the high pressure flow path and the low pressure flow path in a circumferential direction around a valve rotation axis on the rotor plane,
• the second pressure equalization flow path contour is positioned between the high pressure flow path and the low pressure flow path in the circumferential direction around the valve rotation axis on the rotor plane, and
• the second pressure equalization flow path contour is positioned on a side opposite to the first pressure equalization flow path contour on the rotor plane.