二级 G—M 制冷机是一种氦气封闭循环微型制冷机,它分别在77K 和20K 温区提供冷量。它与其它类型的微型制冷机相比,具有转速低、振动小、操作维护方便和寿命长等特点。然而继续提高它的长期运转可靠性还有不少问题有待于深入研究。本文粗略地介绍了冷损分析,着重从二级蓄冷器填料的密封、二级活塞环的磨损、二级胀圈的微变形、系统内油与水的污染及传动部分可靠性等方面进行考虑,以提高二级 G—M 制冷机长期运转可靠性。 The secondary G-M refrigerator is a helium closed cycle miniature refrigerator that provides cooling at 77K and 20K respectively. Compared with other types of miniature refrigerators, it features low speed, small vibration, convenient operation and maintenance and long service life. However, there are still many problems to be further studied in order to continue to improve its long-term operational reliability. This paper gives a brief introduction of cold loss analysis, focusing on the secondary fill cooler seal, secondary piston ring wear, secondary expansion ring micro-deformation, the system of oil and water pollution and transmission reliability , In order to raise the long-term reliability of the secondary G-M refrigerator.