| 摘要 |
An automatic door closer comprises a closer shaft connected to a door for turning therewith and being turnably mounted in the region of one end of an elongated fluid-filled housing. A cam disk fixed to the closer shaft cooperates over rollers carried by a slide to move the latter and a piston rod fixed thereto during opening movement of the door in a first direction. A first piston arranged in the housing divides the latter into a first and a second pressure space and is connected to the piston rod passing through a bore in the first piston for moving therewith in the first direction to thereby reduce the volume of the first pressure space while increasing the volume of the second pressure space. A coiled compression spring arranged about the piston rod biases the first piston to move in a second direction opposite said first direction. A second piston fixed to the free end of the piston rod projects beyond the first piston into a cylinder space formed in a plug closing the other end of the housing. A first plurality of interconnected throttled passages formed in the housing and the plug communicate at opposite ends with the first pressure space and the cylinder space, and a second plurality of interconnected throttled passages communicate at opposite ends respectively with said first and said second pressure space. A valve is arranged in the second plurality of interconnected passages movable between an open position permitting flow of fluid through the second plurality of interconnected passages and a closed position preventing such flow, whereby when the first piston is moved during opening of the door against the pressure of the spring, it can be held in this position by moving the valve to the closed position preventing passage of fluid through the second plurality of passages while the door can be easily turned in either direction. |
