| 摘要 |
PURPOSE:To quicken the solenoid operation and yet to reduce the solenoid heat in a solenoid actuating circuit of an electromagnetic oil pressure valve by disposing a pulse amplitude modulating means in a power transistor driving circuit. CONSTITUTION:A solenoid driving circuit of an electromagnetic valve has solenoid 3, transistor 1, control circuit 6 and pulse amplitude modulating circuit 7. When a voltage having a wave shape like A from the pulse amplitude modulating circuit 7 to the transistor 1, the electric current wave shape which passes in the solenoid 3 becomes like B. As the source voltage is continuously connected from a wave T1 to a wave T2, the electric current rapidly rises. In a span from T2 to T3, the average current flowing in the solenoid 3 is controlled to be above a current which would be flowing if the solenoid 3 is held ON. Thus, the solenoid heat generation is reduced, and the solenoid operation is quickened. |
