PURPOSE: To check a return state especially when a solenoid has been turned off by a method wherein an electric current is made to flow through a coil only for a short time width, the time required until the response waveform of the electric current detected by a resistance for current detection use is changed by a prescribed value is measured and the position of a movable iron core is discriminated.
CONSTITUTION: A resistance 15 for current detection use is connected in series with a coil 11 for a solenoid; a diode 25 is connected in parallel with this series circuit; an electric current can flow through the series circuit composed of the coil 11 and the resistance 15 from a DC power supply 16 via a switch 27. After the solenoid has been turned off, an excitation operation is performed only during a time width during which a movable iron core for the solenoid is hardly moved. The time required until a response waveform is changed by a prescribed value is different according to whether the movable iron core is situated in a prescribed position or not from the difference in a response current waveform due to the difference in an inductance for the solenoid according to the position of the movable iron core. As a result, the position of the movable iron core is discriminated accurately according to its measured value. Thereby, the position of the movable iron core can be checked at any time as required after the solenoid has been turned off.
KAKINUMA TOSHIBUMI
KOMINAMI YUICHI
KIHARA KAZUYUKI
HATANAKA KOSUKE
MITO AKIO
| JPH0428209A | 1992-01-30 |