| 摘要 |
PURPOSE:To prevent the burnout of a motor coil and the damage of a motor due to abnormal heat generation of a heat source by automatically stopping the energization of a coil by detecting a motor lock, and further stopping an electric input to a heat source in response to the stop of the energization. CONSTITUTION:When a motor is locked due to mechanical overload, a current is supplied to coils 1, 2 directly after a switch 17 is turned ON, but a capacitor 67 of a time measuring unit 103 is charged, and when the charging voltage Va becomes larger than Vcc/2, the transistor 78 of an energization stopper 104 is turned ON. Accordingly, the energization of the coils 1, 2 is completely stopped (simultaneously an electric input to the heat source 105 is stopped), and the motor continues the stopped state. Since the generating voltages of the coils 1, 2 are zero, the output currents i1, i2 of a rotation detector 101 become zero, and the transistor 64 of a time measuring unit 103 continues OFF. In other words, a positive feedback loop is composed of a rotation detector 101, the time measuring unit 103, the energization stopper 104, a current supply unit 102, a distributor 100, and the coils 1, 2. |
