| 摘要 |
PROBLEM TO BE SOLVED: To apply a far stronger force than a maximum output of a linear solenoid to a spool to release sticking of the spool by controlling the energization to the linear solenoid. SOLUTION: A spring 29 for returning a plunger 22 of a linear solenoid 20 is installed, and when the linear solenoid 20 is unenergized, a clearanceδis allowed to be generated between opposite end faces of the plunger 22 and a spool 16. When the spool 16 is stuck while the energization to the linear solenoid 20 is controlled, the energization to the linear solenoid 20 is interrupted, and then a maximum current is temporarily applied to the linear solenoid 20 to accelerate the plunger 22 to collide with the spool 16, and thus to release sticking of the spool 16 by impact force of the collision.
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