| 摘要 |
<p>PURPOSE:To realize reduction in size of structure and in manufacturing cost by controlling over-excitation, normal excitation and reverse excitation of a pair of coils of electromagnetic clutch and brake with a single power supply with six transistors. CONSTITUTION:When a transistor 12 is switched ON, a long duration pulse P1 is supplied to the base of a transistor 6 from a PWM oscillation circuit within a short period of time until a torque of electromagnetic clutch and brake rises. Thereby, a heavy current larger than the rated current is supplied in the forward direction of a coil 20 of clutch of the electromagnetic clutch and brake and thereby the coil 20 is over-excited. When an armature of clutch of the electromagnetic clutch and brake is attrated to the attracting surface and the clutch is effectuated, the PWM oscillation circuit oscillates a rated short duration pulse P2 to the base of transistor 6 and thereby the coil 20 is normally excited. When the long duration pulse P1 is supplied to the base of transistor 8, a current larger than the rated current is supplied to the coil 20 as a reverse current and thereby the coil 20 is reversely excited.</p> |
