A NEW TECHNIQUE TO MEASURE EXPERIMENTAL PRESSURE DIAGRAMS OF RECIPROCATING COMPRESSORS

摘要

An experimentally obtained pressure-volume (P-V) diagram is of special significance to compressor engineers. In such experiments, the measurement of valve opening instants are used as reference signals to set the absolute level of the cylinder pressure signal. These valve signal measurements have typically been measured using proximity sensors. However, the original valve system often has to be modified significantly to accommodate the installation of the proximity probes in small fractional horsepower compressors. This modification deteriorates the accuracy of the measurement. In this work, a new measurement technique is applied to detect the valve opening instances accurately. A very small device is developed so that the valve opening instance causes a sudden change of the electric voltage output in its circuit. Experimental pressure diagrams obtained by the new procedure are shown. Advantages of the new method are discussed.