PURPOSE: To enable the liquid compression diagnosis of a compressor without needing any prototype by envelope detection of a piezo-electric signal from a piezo-electric element mounted on the external appearance part of the compressor.
CONSTITUTION: A sensor 2 consisting of a piezo-electric element mounted on a compressor 1 detects a signal caused by the liquid compression of the compressor 1, and the detected signal is subjected to envelope detection by an envelope detection apparatus 3 and indicated on an output apparatus 4. Then, the outputted signal has the same wave form as the actual pressure waveform in timing and form of the peak waveform. Thus, a liquid compression phenomenon can be judged from a threshold line corresponding to the highest pressure line in the normal running and the liquid compression can be confirmed when a peak value of the signal peak waveform exceeds the threshold line.
KAMITSUJI TOSHIO
UMEOKA IKUTOMO
HAMANO YASUKI
