Abstract:

The health of a reciprocating air compressor can affect the time of occurrence of valve impacts within the compressor. A computer simulation reveals useful insight into the nature of the timing changes, which provides a basis for automated prognosis of the machine health. As an example, consider that the opening impact of a leaky discharge valve is delayed by an amount proportional to the size of the leak. The effect that the leak has on the efficiency of the compressor can be determined using the simulation, and a threshold for lost efficiency can be tied to the time of occurrence of the valve impact. Using the computer simulation as an aid, the vibration transients generated by the impacts can be clearly identified in the vibration signal measured on the exterior of the compressor. The time of occurrence of the impacts can then be accurately determined from the measured vibration using minimum-phase processing, a sliding exponential window, and statistical curve fitting. [See NOISE-CON Proceedings for full paper.]