| 摘要 |
<p>A door closer hold open assembly connectable to a door for closing a held open door in response to a control signal includes a housing, a linkage assembly connectable to the door, biasing means providing a restoring force to move the door to the closed position and a main piston assembly disposed in the housing and actuatable by the linkage to move the main piston against the force of the biasing means. A fluid chamber is disposed in the housing for exerting a force on the main piston to balance the force of the biasing means in a desired door position to maintain the main piston and the door in the position it was last moved to by the linkage assembly. First and second independently operable valve means are disposed in a parallel circuit and are operable to control the flow of fluid from the chamber. The first valve means is electrically controlled from a closed position to an open position and the second valve means is resiliently biased toward a closed position. The second valve means is operable upon the fluid in the chamber reaching a predetermined pressure to open against the resilient biasing force and provide for fluid flow therethrough from the chamber. The fluid in the chamber exerts a biasing force on the first valve means when the first valve means is in its closed position to bias the first valve means toward the closed position.</p> |
