| 摘要 |
The control device is allocated to a DC motor which can rotate in opposite rotation directions and is used as a drive for components which can move into two limit positions, especially for opening and closing garage doors. In this case, switching devices (10, 16) are provided for the DC motor, which switching devices switch said motor off and on and/or reverse the direction of the motor current and hence the rotation direction of the motor. An overcurrent switching appliance (12) trips in response to current surges which occur when the load on the motor increases, especially during forced braking of the motor in the limit positions of the component or if an obstruction is present in the movement path. The switching devices (10, 16) have an on/off switch (16) and a switching appliance (10) which operates in a stepped manner and can be switched into an "interrupt" switching position whenever the overcurrent switching appliance (12) trips and into a "motor current on" switching position whenever the on/off switch (16) is operated, in accordance with the following switching cycle: interruption - motor current on and anticlockwise running - interruption - motor current on and clockwise running. As a result of this arrangement, limit switches are obviated and hence their adjustment and maintenance work. At the same time, reliable protection against overloading the DC motor is achieved. <IMAGE> |
