Visual experimental investigation on the stability of pressure regulating poppet valve

The unstable vibration of a poppet valve drastically fluctuates pressure which directly affects the stability, reliability and safety of a hydraulic system. The unstable vibration of the poppet and cavitation is studied using visual experiments. Experimental results show that for a poppet valve, an orifice at the front of the valve cavity, the compressibility of oil in the sensitive cavity will lead poppet to unstable vibrations. For poppet valve without orifice, the instable vibration appears as three states: impact valve seat, transition (impact or non-impact valve seat occurs randomly) and does not impact valve seat. When poppet impacts valve seat, there will be severe cavitation phenomenon at the valve port. Although poppet does not impact valve seat, the cavitation come up is affected by the pressure difference at the port or vibration amplitude of the poppet. In addition, both of the flow pulsation of the hydraulic pump and the coupling between the poppet and pipeline system will lead the poppet to be unstable.