Real Time Diagnosis System of Diesel Engine by Statistical Sound Analysis

Abstract

This paper describes the system which abnormal condition of engine is diagnosed by its radiated sound. Valve clearance of the exhaust valve and injection pressure of fuel valve are selected as factors indicating abnormalities, and valve clearance experiments are carried out for various valve clearances ranging from 0.1 to 1.3mm and injection pressure experiment are for injection pressures ranging from 110kgf/cm² {10.8MPa} to 300kgf/cm² {29.4MPa} . Standard values of valve clearance and pressures are 0.4mm and 190kgf/cm² {18.6MPa}, respectively.
In this system, the diagnostic algorithm consists of several segments, which deal with sound picking, degitalization of sound signal, spectral analysis and statistical analysis. These processes are handled quickly and continuously by a microcomputer. Using above-mentioned system, the diagnose is tried for the operating engine. As a result, the diagnose takes time of 11.1 seconds each, and its results are successfully obtained.