The utility model discloses a passive
piston phase modulation type GM
pulse tube refrigerator which comprises a passive
phase modulation mechanism, a compressor, a
cold finger assembly and a
phase modulation connecting
pipe, the passive phase modulation mechanism is connected to the
cold finger assembly through the phase modulation connecting
pipe, and the
cold finger assembly is connected to the compressor through a
helium pipe. The passive phase modulation mechanism comprises an air cylinder, a column spring, a spring seat and a phase modulation
piston located in the air cylinder. The phase modulation
piston reciprocates under the action of alternating
airflow at the hot end of the pulse tube, the
stroke of the phase modulation piston is controlled by adjusting parameters such as spring rigidity, the
mass and the
diameter of the phase modulation piston, passive phase modulation is achieved, and therefore the pulse tube hot end
mass flow and
pressure wave phase angle is adjusted, and the optimal
phase angle of the pulse tube hot end
mass flow and
pressure wave is obtained through comparison. An optimal passive phase
modulation function is realized, and high efficiency of the whole
machine is realized; and a passive phase modulation mechanism is adopted, the acoustic power of the hot end of the pulse tube can be recycled while passive phase modulation is conducted, the
overall efficiency is further improved, and therefore the GM
pulse tube refrigerator with high reliability and high
refrigeration efficiency is achieved.