| 摘要 |
PURPOSE:To shorten door opening and closing times by shortcircuiting a resistor when the load of a motor increases from the lower load limit value to increase a supplying voltage and reducing the limit value in response to the number of shortcircuits. CONSTITUTION:When an operation switch 31 is operated, an electromagnetic coil 51 or 61 of a relay 50 or 60 is excited. Simultaneously, the exciting coil 71 of a relay 70 is excited to close the shortcircuiting contact 72 of a resistor 80 to supply a voltage from a DC power source B to a DC motor M. When the motor M rotates, the coil 71 of the relay 70 is deenergized to open the contact 72. A microcomputer 130 excites the coil 71 of the relay 70 for the prescribed time when the rotating speed signal from a speed sensor 120 reduces to the lower speed limit value or lower. The limit value is sequentially increased whenever the coil 71 is excited. |
