Swing-door drive

摘要

An automatic swing-door drive with a hydraulic piston/cylinder unit 7, 8 with closer spring 10 and an opening motor consisting of an electric motor 5 and hydraulic pump 4 is described. So that even lower-power opening motors can be used and to ensure a relatively small design, provision is made for pre-storing energy in the closer spring 10 before the opening of the door. For this purpose, there is provision for supporting the closer spring 10 at one end on a piston 7 of the piston/cylinder unit and at its other end on a spring piston 21, and for the closer spring 10 to be pretensionable, before the opening of the door, as a result of the positive displacement of the spring piston 21. The displacement of the spring piston 21 takes place via the hydraulic pump 4.