Abstract:
The target of this thesis is the detection of fault in engine through its sound using
spectral analysis. The sound signals of four selected engine parts were examined using spectral analysis to detect the fault in Toyota 3B engine. These sound
signals were sound from normal Toyota 3B engine, sound from faulty advanced
engine, sound from faulty retarded engine and sound from insufficient coolant
amount in Toyota 3B engine. Sound capturing process was occurred by using
laptop, mini-jack, microphone and these sound signals were recorded in isolated
room to avoid interference of the surrounding sounds. Three signal visualization
techniques time wave form, line spectrum and power spectral density were used. The plots of line spectrum and power spectral density were obtained after time
domain is converted to frequency domain with help of FFT. This conversion was
performed using MATLAB soft ware. In this thesis the dominant frequency of the
normal Toyota 3B engine was 150Hz and the dominant frequency of the selected
engine parts such as faulty advanced, faulty retarded and insufficient coolant
amount in Toyota 3B were 137.50Hz, 125.73Hz and 148.50Hz respectively. These
indicate that each sound signal recorded from selected engine parts had their
own unique frequency spectrum. Therefore, one can detect the fault in Toyota 3B
engine parts using its frequency spectrum since each engine part has its own
spectral representation.
