| 摘要 |
A door closer comprising: (a) a housing for fitting into a door, the housing having a mounting plate with an opening adjacent to a central bore of the housing; (b) a tension member extending longitudinally within the central bore of the housing and extending outwardly of the housing through the opening to define an end thereof for fitting to a door frame; (c) a movable body within the housing and adapted for longitudinal movement within the central bore, the movable body being connected to the tension member; (d) a spring within the housing and biasing the movable body in a first direction away from the mounting plate so as to urge the tension member inwardly of the housing in a door closing motion; (e) a hydraulic assembly for hydraulically controlling the longitudinal movement of the movable body, the hydraulic assembly being disposed within the central bore of the housing; wherein the hydraulic assembly comprises a piston coupled to the housing and slidable in a fluid-filled chamber within the movable body, wherein the piston divides the chamber into two compartments, and the piston comprises a valve mechanism which opens to permit relatively free movement of the fluid from one compartment to the other when the movable body is moved relative to the piston in a second direction, opposite to the first direction, in response to movement of the tension member outwardly of the housing but closes to present resistance to movement of the movable body in the first direction, wherein the valve mechanism of the piston comprises a boss fitted to a piston shaft and defining an annular sealing face, a longitudinally extending channel member integral with the boss, the channel member having at least one longitudinal channel therein which terminates at a closed end near to but spaced from the annular sealing face, an annular seal member fitted around the channel member, the annular seal member being disposed for longitudinal sliding motion on the channel member, between sealed and unsealed positions, the at least one longitudinal channel extending between opposite sides of the annular seal member, the seal member having an annular end sealing surface facing the boss, and a circumferentially outer surface of the annular seal member providing a sealing engagement with the movable body. |
