| 摘要 |
PROBLEM TO BE SOLVED: To properly reduce a low frequency sound generated by vibration of a vibration body, by accurately detecting the vibration of the vibration body of a vibrational screening machine, even if dust is generated.SOLUTION: The vibration body of the respective vibrational screening machines 1 and 3 is detected by non-optical proximity sensors 5a and 5b arranged in the vicinity of its vibration range, and a frequency phase difference detection part 11 detects vibration frequencies f1 and f2 of the respective vibration bodies and a phase difference &thetas; of the vibration from its detection signal. A phase difference control part 15 calculates a control volume alpha for approaching the phase difference &thetas; to a target phase difference based on a difference u2 between the phase difference &thetas; of the vibration of the detected respective vibration bodies and a predetermined target phase difference. The calculated control volume alpha is added to the difference between the vibration frequencies f1 and f2 of the respective vibration bodies by an adder 17, and is inputted to a frequency control part 13. The frequency control part 13 outputs motor speed command voltage for reducing the difference between the vibration frequencies f1 and f2 of the respective vibration bodies detected by the frequency phase difference detection part 11. |
