| 摘要 |
PROBLEM TO BE SOLVED: To separately detect the start of a movable piece and the clearance between the movable piece and a valve shaft with excellent accuracy in an solenoid-driven valve device. SOLUTION: The holding current flowing in a closing side coil is completed slightly before the valve-opening timing to allow the circulating current to flow, the timing t1 of the minimum point of the waveform of the circulating current is detected, and it is judged by this timing t1 that a movable core is started to move. At this timing, the circulating current is immediately shut off to generate the flyback voltage, the timing t2 of the third inflection point shown in the waveform of this flyback voltage, and it is judged by this timing that a plunger of the movable core is collided with a valve shaft. The time (t2-t1) until the movable core is collided with the valve shaft after it is started is calculated, and the clearance between the plunger and the valve shaft is calculated based on the time (t2-t1).
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