针对螺旋密封中的“气吞”等现象 ,运用“演化”的思路 ,对其产生的机理进行了分析。指出螺旋密封实际上是一种具有复合作用的机械装置 ,就是说 ,它存在一临界值 ,在临界值以下 ,是一种螺旋输送装置 ;在临界值以上 ,则是一种具有轴向变容积式吸排型的“零流量”的泵。而螺旋密封中的“气吞”现象是该密封装置所特有的。同时指出 ,螺旋密封与四杆机构具有“亲缘关系” ,即螺旋密封是四杆机构演化的结果 Aiming at the phenomenon of “gas swallowing” in spiral sealing, the mechanism of “evolution” was analyzed. It is pointed out that the screw seal is actually a mechanical device with compound action, that is to say, it has a critical value below the critical value, which is a screw conveying device. Above the critical value, it is a mechanical device with axial variable volume Suction type of “zero flow” of the pump. The “swallowing” phenomenon in the screw seal is unique to the seal. Also pointed out that the screw seal and the four-bar mechanism has a “genetic relationship”, that is, the spiral seal is the result of the evolution of four-bar mechanism