| 摘要 |
A door closer includes a cylinder-and-piston arrangement in which the piston is received in the cylinder for displacement between a rest position corresponding to a closed position of the door, and an end position corresponding to the fully open position of the door, through an intermediate position corresponding to a partly opened position of the door. The piston subdivides the interior of the cylinder into at least two compartments which are in communication with one another via at least two passages one of which is closable in any position of the piston by means of an electromagnetically operated valve, the other passage being open when the piston is between the rest and the intermediate position and closed when the piston is between the intermediate and the end position. A spring biases the piston toward the rest position so that, when the electromagnetically operated valve is opened, the spring will cause the door to close regardless of its position, while the spring will also close the door regardless of whether the electromagnetically operated valve is closed or opened, from any position between the above-mentioned partially open position of the door and the closed position of the door, due to the flow of a damping fluid between the two compartments through the other passage. The valve which closes and opens the other passage may be constructed as an elongated pin mounted on the cylinder and extending into the other passage, the pin having a first portion received in the other passage with clearance between the rest and the intermediate position of the piston, and a second portion sealingly received in the passage between the intermediate and the end position of the piston. The first and second portions may merge with one another via a conical portion which determines the size of the clearance when at least partially received in the other passage. The piston may have two piston heads each delimiting one of the compartments and connected with one another via a toothed rack under the formation of a third compartment between the two piston heads. A pinion of a door-closing linkage then meshes with the toothed rack. Additional passages and additional valves in such passages may be provided which permit overriding of the action of the electromagnetically operated valve by exerting force on the door, and the increase in the degree of opening of the door. |
