| 摘要 |
PURPOSE:To enable a positive operation by connecting a control unit sending out an intermittent closing signal to a switching element serially connected to a control switch, thereby periodically applying a DC current to a coil. CONSTITUTION:One end of a coil 7 of a DC solenoid 6 is connected via a control switch 18 to the positive side of a DC power supply 20, and a transistor 21 as a switching element is connected between the other end of the coil 7 and the negative side of the DC power supply. To this transistor 21, an oscillator circuit 22 oscillating a period pulse of a fixed period simultaneously with the closure of the control switch 18 is connected so as to input the oscillation output to the base. The output terminal of an inverting amplifier 24 in the output stage is connected via a base resistor 30 to the base of the transistor 21, and a diode 31 for absorbing the surge current is connected in parallel with the coil 7. Since, with this, a large current continues to flow through the coil 7 until a valve body 15 departs from a valve seat 17 and a moving core 12 starts to move, an electromagnetic switching valve 1 can positively be operated.
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