Model Study on the Oil Stiction of a Discharge Reed Valve in Compressors

Abstract

In a discharge reed valve for compressors, the oil stiction by the oil film between the reed and the valve seat is investigated experimentally, and a simulation model is developed. Through a model experiment, the initial oil film thickness is measured by an interferometry method, and the valve displacement and the bore pressure are measured from the stiction to the valve opening. The opening delay time together with the initial oil film thickness is measured while changing the contact area and the oil species. In the simulation model, the deformation of the reed and the pressure of the oil film as a result of cavitation are coupled. In order to take into account the tensile stress in the oil film, a cavitation model directly simulating the expansion of cavitation bubbles is developed (herein, dynamic cavitation model). In the experiment, a smaller contact area, a larger initial film thickness, and a smaller oil viscosity yield a shorter delay. In the simulation, the dynamic cavitation model is advantageous in representing the experimental delay time. In particular, with respect to the relationship between the initial film thickness and the delay time, the dynamic cavitation model with an initial bubble radius that depends on the oil film thickness yields results similar to the experimental results.