PURPOSE: To rapidly and accurately diagnose trouble, by performing judgement by comparing the sound pressure integrated value within the specific frequency range in the output signal of an acoustic sensor arranged at a required position at the time of the seating of a discharge value by a position detector with a normal value.
CONSTITUTION: The output signal of the acoustic sensor 108 arranged in the vicinity of the value seat 105 passing through a gate circuit 110 opened when the discharge valve 104 is seated on the valve seat 105 by a position detector 109 is analyzed by a frequency analyzer 111. Sound pressure of frequency of 10W40kHz is integrated by an operation apparatus 112 to be compared with an preliminarily operated and determined normal value to judge the trouble of the discharge valve. By judgement by operation but not by judgement based on the visual observation of this incation drawing, the trouble of the discharge value of a diesel engine can be diagnosed rapidly and accurately without subjectivity.
Takaishi, Takeo
Takagi, Shigeru
Miyazaki, Sadao
