A Fundamental Study on Valve Impact Stress in Refrigeration Compressor

The purpose of this study is to get fundamental knowledge of the valve impact stress by clarifying wave propagation mechanism in two bars which are simulated to a valve seat or valve stop and a valve. Axially uniform stress in finite cylindrical elastic bars subjected to velocity-impact loading is considered on the bases of elementary equations of energy. A technique is developed for measuring the strains transmitted by the longitudinal impact of two bars and the variations in the strain are measured under three kinds of bar lengths and two different restraints at the end point. Comparing the theoretical results with the experimental results, the effects of the bar lengths and restraint conditions on the propagation of the stress wave along a slender cylindrical bars are examined. On the bases of these results, the impact duration and maximum impact stress of valves and the transient response of strain gauges are discussed. Moreover, predominant impact stress affecting impact fatigue failure of valves is also discussed.