Noise Diagnostics and Solution Development on an Engine using Acoustic Imaging

摘要

This study was aimed at diagnosing the actual noise source(s) for certain offensive noise from an engine and developing solutions. Traditional methods like Intensity scan using an Intensity Probe could not be used since the issue was for multiple speeds and especially noticeable during a run up. An intensity probe scan of the whole engine surface can only be conducted for a steady speed. It would have been impractical to scan the whole engine for all those engine speeds with an intensity probe. We conducted an acoustic imaging test covering four sides of the engine. The results revealed that for the RPM and frequency range that was identified, the noise source was the Oil Pan, which was simply resonating to the vibration from the engine and probably the balancing module, which till then was believed to be the noise source. This insight clearly shifted the focus from the balancing module to the oil pan resonance. To solve the issue, four different configurations of the oil pans and balancing modules were evaluated. This exercise showed that a better design of the oil pan was the solution. This saved valuable resources, which would have been wasted chasing the wrong source.