| 摘要 |
<p>Apparatus for securing an emergency exit door includes a bolt for engaging a keeper, a dogging mechanism for dogging the bolt and a fluid throttling device disposed between the bolt and dogging mechanism. An electrical timer is connected to the dogging mechanism by a solenoid and starts to count upon an attempt to open the door. After a predetermined time interval has run, the electrical timer releases the dogging mechanism and allows the door to dopen. If the electrical timer fails to release the dogging mechanism, the door will still open if pushed due to operation of the fluid throttling device, which slowly shortens under pressure, allowing the bolt to clear the keeper. In accordance with a preferred embodiment of the invention, the bolt is mounted on the door frame and the keeper on the door so that the door may be conveniently retrofitted with the invention. In order to readily align the keeper with the bolt, the keeper is loosely mounted and guided into alignment with the bolt by a bevelled guide. Upon being latched by the bolt, the keeper is held rigidly between the guide and the bolt. After the door has been opened, it cannot be resecured for a predetermined relock time interval. If the door is shut within this relock time interval, the relock time interval restarts, allowing the door to be reopened without a delay. Each time the door is shut after being opened, the relock time interval is restarted. In order to maximize reliability, Hall-Effect switches are utilized to monitor the position and movement of the bolt and the condition of the solenoid.</p> |
