PURPOSE: To prevent free characteristics from being caused by mistake at the time of the control of locking characteristics by bringing low current near specific current for keeping a joint in the first control condition, and bringing low current near specific current after the specific current passes for a specific time for keeping the joint in the second control condition.
CONSTITUTION: This joint is composed of a movable magnetic substance 24 which displaces an actuator by the energization of a solenoid coil 23 and a spring which returns it to a basic condition, and increases or decreases flowing resistance with control valves 26, 30 according to the displacement of the movable magnetic substance 24. For keeping the joint in the first control condition, low current is brought near specific current sufficient to keep it in the first control condition. On the other hand, for keeping the joint in the second control condition, the current determined by power voltage, and resistance of the solenoid coil 23 and a circuit is passed for a specific time without limiting current, and then is controlled so as to be brought near specific current sufficient to keep the second control condition. Since duty ratio which becomes objective current when current passes most easily is formed and is controlled so as to obtain the objective current by current feedback, it is possible to prevent a free characteristics from being caused at the time of locking characteristics control.
TAKADA MASAHIRO
YAMASHITA KENICHI
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