| 摘要 |
PROBLEM TO BE SOLVED: To further properly set a threshold value becoming a standard for performing deposit removing operation in a valve control device for variably controlling the effective opening area of a flow passage by the rotational movement of a butterfly valve. SOLUTION: A rotational movement range of the butterfly valve is divided into a plurality by a valve abnormality determining means of the valve control device, and threshold values CI and CII are set and prestored with respective divided rotational movement ranges I and II to a rotational resistance force index value corresponding to rotational resistance force acting against the rotational movement of the butterfly valve, and a determination is made on whether or not the rotational movement of the butterfly valve is slackened by comparing a detecting value of the rotational resistance force index value with the threshold values CI and CII in the respective rotational movement ranges. Thus, the further proper threshold values CI and CII can be set more than when uniformly setting the threshold values regardless of a rotational movement position like a conventional case. COPYRIGHT: (C)2007,JPO&INPIT
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