| CPC F25B 9/14 (2013.01) | 9 Claims |
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1. A cryocooler comprising:
a cylinder;
a displacer disposed inside the cylinder and driven to reciprocate by a gas pressure;
a collar rigidly connected to the displacer to reciprocate together with the displacer;
a collar chamber divided into an upper section and a lower section by the collar;
a seal portion provided between the displacer and the cylinder to seal the lower section;
a lower bumper provided in the lower section to mitigate interference between the displacer and the cylinder when the displacer is located at a bottom dead center; and
a communication passage formed in the collar or in the collar chamber to ensure communication between the upper section and the lower section when the displacer is located at the bottom dead center,
wherein the displacer forms an expansion chamber with the cylinder at an axial end thereof, and forms a room temperature chamber with the cylinder at an opposite axial end thereof,
a first gap is radially inwardly adjacent to an inner peripheral surface of the collar, and a second gap is radially outwardly adjacent to an outer peripheral surface of the collar,
the upper section of the collar chamber communicates with the room temperature chamber through the first gap,
the lower section of the collar chamber communicates with the room temperature chamber through the first gap, the upper section, and the second gap, and
the communication between the lower section and the upper section through the second gap is blocked when the displacer is located at the bottom dead center.
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