電空弁ポジショナの動特性の改善 : 第2報, 発振現象の解析

概要

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This paper is concerned with the analysis of the dynamics of an electropneumatic valve positioner. When this valve positioner is surrounded by combustible gas, the electrical control circuit must be positioned far from the actuator of the valve by using the long pneumatic tube as a safety measure. However, if the length of the pneumatic tube exceeds a certain length, the hunting will occur to the drive shaft of the actuator due to the time lag of the pneumatic pressure signals. This report investigates the dynamics of this hunting from both experimental and theoretical viewpoints. First, the operating principle of the valve positioner and its experimental apparatus are explained. Second, the behavior of the hunting and its generating conditions are clarified through experiments. Third, supposing that the time lag due to the pneumatic tube is a dead-time element, mathematical models of the valve positioner are obtained. Based on these models, the stability limits are found by Nyquist diagram and the transient responses of the drive shaft, including the hunting, are analyzed numerically. Throughout these studies, we obtain elementary materials to eliminate the hunting.
社団法人日本機械学会の論文
1990-04-25