| 摘要 |
PROBLEM TO BE SOLVED: To provide a field valve monitoring device not needing an external power source in detecting opening/closing of a field valve. SOLUTION: A disc 14 is rotated in interlocking with a handle 12 of the field valve 11 and has a slit on its surface. A first piezoelectric sensor 16a is kept into contact with the disc 14 at a full-open position of stroke of a valve rod 13, and is moved between a full-open position and a full-close position while vibrated by the slit of the disc 14, when the handle of the field valve 11 is rotated and operated between the full-open position and the full-close position. Further a second piezoelectric sensor 16b is kept into contact with the disc 14 at the full-close position of the stroke of the valve rod 13, and vibrated by the slit of the disc 14 when the handle 12 of the field valve 11 is rotated and operated at the full-close position. An opening/closing determining device 18 determines an opening/closing state of the field valve 11 on the basis of electric power generated from the first piezoelectric sensor 16a and the second piezoelectric sensor 16b. COPYRIGHT: (C)2007,JPO&INPIT
|
