| 摘要 |
<p>A door closer comprises a housing 11 with a spindle 10 which rotates in response to the door being moved between open and closed positions. A piston 12 is disposed for movement in the axial direction. A biasing member such as a spring 13 biases the piston and spindle to a first position. A cam associated with the piston converts rotational movement of the piston into axial movement; the cam may be a helical groove 30 which engages with ball bearing 31 located in the housing; a hydraulic damper may be provided and a one-way seal included between the piston and housing. In an alternative arrangement a door closer comprising two cams is provided wherein a second cam 28 may function to provide a stable position, e.g. when the door is closed. In an alternative arrangement the housing is of plastic and at least a portion of the housing in which the piston runs is received in a metal sleeve 34. In another arrangement the housing is plastic and moulded around at least one metal liner that defines either a hydraulic fluid passage, piston bearing surface, sealing surface or a threaded bore. In another arrangement a door closer is provided wherein the piston biasing force is adjustable by means of an adjustable retaining cap.</p> |
