原文：Silent oil free air compressor selection criteria
Means that for the laboratory (universities, research institutions, etc.) environment, use the air compressor, requires that the machine precision, more reliability, environmental protection and quiet, fresh and clean air. Emissions laboratory in less than 1m3/min more micro-screw air compressor reciprocating air compressor, also known as Silent oil free air compressor, also called micro-screw sway foreign air compressor. Its working principle is: single-axis drive motor rotates the compressor crankshaft, connecting rod of the drive through with self-lubricating without adding any lubricant will make reciprocating motion of the piston, the cylinder wall, cylinder head and piston top surface of the composition of volume of work will change periodically. Piston compressor piston from the cylinder head office begin to exercise, work within the cylinder volume increases, then, the gas that is along the inlet pipe, open the intake valve and into the cylinder until the volume of work when the date changes to the maximum , intake valve closing; piston compressor reverse movement of the piston, cylinder working volume reduced, the gas pressure increases, when the cylinder pressure reached and slightly higher than the exhaust pressure, the exhaust valve opens, exhaust gas cylinders until the piston up to the limit position, exhaust valve closed. When the piston compressor piston opposite direction again, the above process repeated. Ie: piston compressor crankshaft one revolution, a reciprocating piston, the cylinder have to achieve the intake, compression, exhaust the process to complete a working cycle. Single cylinder's structural design makes the compressor gas flow in the cylinder when the rated speed must double, and in vibration and noise control have been well controlled.
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原文：Silent oil free air compressor selection criteria

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静音无油空压机的选型标准
　 是指那种适合在实验室（高校、科研机构等）环境下使用的空压机，要求机器精密、可靠性更强、环保宁静、压缩空气清新清洁。排量在小于1m3/min的实验室用空压机多是微型螺杆往复式空压机，也称静音无油空压机，国外还叫微型螺杆摇摆式空压机。其工作原理是：电机单轴驱动压缩机曲轴旋转时，通过连杆的传动，具有自润滑而不添加任何润滑剂的活塞便做往复运动，由气缸内壁、气缸盖和活塞顶面所构成的工作容积则会发生周期性变化。活塞式压缩机的活塞从气缸盖处开始运动时，气缸内的工作容积逐渐增大，这时，气体即沿着进气管，推开进气阀而进入气缸，直到工作容积变到{zd0}时为止，进气阀关闭；活塞式压缩机的活塞反向运动时，气缸内工作容积缩小，气体压力升高，当气缸内压力达到并略高于排气压力时，排气阀打开，气体排出气缸，直到活塞运动到极限位置为止，排气阀关闭。当活塞式压缩机的活塞再次反向运动时，上述过程重复出现。即：活塞式压缩机的曲轴旋转一周，活塞往复一次，气缸内相继实现进气、压缩、排气的过程，即完成一个工作循环。单轴双缸的结构设计使压缩机气体流量在额定转速一定时为单缸的两倍，而且在振动噪音控制上得到了很好的控制。