自润滑活塞环的压力分布及摩擦热研究

活塞环是高压无油压缩机中的重要易损件,而活塞环间的压力分布和活塞环与气缸间的摩擦热是影响其寿命的两个最主要因素。建立了活塞环间压力分布的数学模型,揭示了活塞环非均匀磨损的机理;同时搭建了试验台,通过动态压力传感器测量了活塞环间的压力分布,验证了理论模型。研究结果表明,活塞环开口间隙相同时,各环间压力分布严重不均,第一道活塞环承受75%以上的压差,这是引起不均匀磨损从而导致快速失效的根源;通过设计不同切口大小的活塞环等措施,可以使各环间压力分布均匀化,提高环组寿命。影响活塞环寿命的另一个因素是由摩擦热引起的高温,通过有限元方法研究了活塞环与气缸间的摩擦热生成和传递过程。

Investigation of the Pressure Distribution and the Frictional Heat on Self-lubricated Piston Rings

Piston ring sealing is of great importance in oil-free reciprocating compressors for high pressure application.Pressure distribution and frictional heat between piston rings and cylinder have been investigated with the aim of finding the key factors influencing the life time of piston rings.A mathematical model simulating the unsteady flow within the gaps of piston rings was established to present the pressure distribution and disclose the mechanism of the uneven abrasion of different rings.Meanwhile,the test rig was built to validate the mathematic model,on which the pressure distributions between the piston rings were measured using pressure sensors.The results showed that the severe non-uniformity of the pressure distribution between piston rings was suggested to be the root cause of premature failure of the sealing rings.The pressure distributions between the rings were always dramatically non-uniform with the same ring cut,and the first ring afforded more than 75% of the total pressure difference.Then the method to equalize the pressure difference through each ring was proposed by re-distributing the cutting size of each ring,and it was also validated experimentally.Another factor that influenced the life time of piston ring was the high temperature caused by the frictional heat,so this paper also investigated the frictional heat generation and conduction between piston rings and cylinder by the Finite Element Method.