Automatic door closer.

摘要

A door closer in the form of a floor spring has two coaxial cams (4 and 5) fastened to its door spigot (3). One cam (4) acts via a roller (6) on the rod (7) of a restoring spring unit (8). The other cam (5) acts via a roller (9) and lever (10) on the rod (13) of a damper/assist unit (14). This unit (Fig 4) has a spring (25) which acts on a piston (24) arranged to drive oil through a hydraulic circuit (26) in which there is an automatic throttle (27) (Fig 5). The shape of the second cam (5) is such that as soon as the door is "cracked" the force of the spring (25) in the damper/assist unit (14) acts to assist the door to open in opposition to the spring in the restoring unit (8). The throttle (27) is arranged to apply no significant damping to the movement of the piston (24) in this direction. However, when the door is released and closes under the force of the spring in the restoring unit (8) there is a reversal of the flow direction in the hydraulic circuit (26) as the rod (13) of damper/assist unit (14) is pushed in, and the throttle (27) is arranged to apply a significant damping action to the piston (24) in this direction.