| 摘要 |
A closure arrangement for an opening comprises a closure structure (1) slidable sideways relative to the opening, an electric motor drive (7), preferably three-phase, connected by means of an endless chain (8) to the closure structure (1) to effect the sliding and an automatic electric switching device (10) comprising a motor current sensor operable to switch off the motor (7) if the current exceeds a predetermined value. The current sensor may be a relay or resistor in circuit with the motor (7) or isolated therefrom by a transformer. The sensor may operate the on-off manually operable switch (10) for the motor (7) or may operate an auxiliary switch provided with latching and resetting means. The endless chain (8) may run along the top edge of the opening in a channel (3) from which the closure structure (1) is slidably supported, the closure structure (1) comprising sections (2) pivotally connected to adjacent sections (2) along their vertical edges. <IMAGE> |
