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Diagnostic system and method, especially for a valve

  • US 6,637,267 B2
  • Filed: 03/29/2002
  • Issued: 10/28/2003
  • Est. Priority Date: 09/30/1999
  • Status: Expired due to Fees
First Claim
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1. A diagnostic system comprising:

  • a sensor operable to sense structure-borne noise;

    an evaluation unit operable to evaluate a recorded measurement signal, wherein the measurement signal is representative of at least a portion of the structure-borne noise and said evaluation unit is configured such that a spectral region of the measurement signal above a first limit frequency, where the first limit frequency is greater than 50 kHz, is evaluated for fault detection, and a fault indication signal is generated if an intensity of the measurement signal in the spectral region exceeds a threshold; and

    a determining means for determining a strength of background noise in the measurement signal by measuring a signal strength in a spectral region above a third limit frequency, the third limit frequency being greater than a second limit frequency and selected such that influence on the measurement signal by cavitation noise is minimized, determining a strength of the cavitation noise in the measurement signal by measuring the signal strength in a spectral region between the second limit frequency and the third limit frequency, and determining the threshold value based on the strength of the background noise; and

    generating the fault indication signal if the strength of the cavitation noise exceeds the threshold value.

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