液气开关启闭特性分析

液气开关作为控制系统中气动油泵的主控开关,控制系统油液压力。当系统油压足够大时,液气开关切断气源,气动油泵停止充压;当系统油压不足时,液气开关连通气源,气动油泵自动补压,直至液气开关切断气源,液气开关启闭特性直接影响系统压力稳定性。通过数值建模,从气源压力、弹簧刚度、机构摩擦力3个方面对液气开关启闭特性分析,并进行试验验证。分析显示,气源压力和机构摩擦力对液气开关启闭特性影响较小,弹簧刚度对其影响较大。试验结果显示,当气源压力在0.65～0.9 MPa之间时,为减小启闭压差,弹簧刚度应设计在94～97.3 N/mm之间为宜。

Opening and Closing Characteristics of Hydro-pneumatic Switch

As the main control switch of pneumatic pump in the control system, the hydro-pneumatic switch controls the system hydraulic pressure. When the system oil pressure is higher, hydro-pneumatic switch cuts off the air source and the pneumatic pump stops working. When the system oil pressure decreases, the pneumatic pump automatically fills the pressure until the gas source is cut off by the hydro-pneumatic switch. The opening and closing characteristics of hydro-pneumatic switch directly affect the system pressure stability. Numerical modeling is used to analyze the influencing factors of the air source pressure, the spring stiffness and the mechanism friction are verified by experiment. The results show that the air source pressure and the mechanism friction have little influence on the opening and closing characteristics of hydro-pneumatic switch, while the spring stiffness has great influence on it. When the air source pressure is between 0.65～0.9 MPa, the 94~97.3 N/mm spring stiffness can reduce the opening and closing pressure difference.