| 摘要 |
PROBLEM TO BE SOLVED: To diagnose whether a driving state of an engine is sound by converting acceleration data of a cylinder block to a cylinder internal pressure via a frequency response function. SOLUTION: An acceleration response of a cylinder block 103 detected by an acceleration detector 1 is input to a Fourier transform device 2, and Fourier- transformed to a frequency region. A spectrum is output to a divider 3. A frequency response function-setting device 4 sets a frequency response function between a cylinder internal pressure and a vibration response of the cylinder block 103 as preliminarily measured frequency response function data. The divider 3 divides the spectrum output from the Fourier transform device 2 by the frequency response function, and obtains an estimated value of a spectrum of the internal pressure. Whether the cylinder internal pressure is sound is detected time by time at a comparing/diagnosing part 5 with the use of a cylinder internal pressure database 13. The result is output from a diagnosis result output part 7.
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