On the Stability of a Poppet Valve with an Elastic Support : 1st Report, Considering the Effect of the Inlet Piping System

Abstract

A conical type hydraulic poppet valve with an elastic support (e.g. a helical spring) builds up a complex vibration system with the inlet and outlet piping, and often induces a violent vibration making noise and leading the whole system into unstable conditions. In this report, the author derives the characteristic equation of the whole system including a poppet valve and inlet and outlet pipings. Some theoretical considerations are developed neglecting the outlet piping. The effect of the nonlinearity of the system is also discussed. Some experiments were conducted without outlet piping and varying the length of the inlet piping, spring constant, inlet pressure and other parameters. The experimental results agree fairly well with the theory. The conditions determining the disturbance frequency range in which instability occurs are obtained as a function of length of inlet piping, spring constant, inlet pressure, valve lift, valve shape and Reynolds number.