| 摘要 |
The invention proceeds from a drive device which is used, in particular, for the closing unit, the injection unit or the ejectors of a plastic injection molding machine and which has a drive element movable axially by means of an electric motor and a hydraulic unit movable as a result of the movement of the drive element in the same direction as the latter. In drive devices for the applications mentioned, it is important first to execute a rapid adjusting movement and then to exert high forces. In a known drive device having the features mentioned, the hydraulic unit is a hydraulic cylinder which, during the adjusting movement, is adjusted by the electric motor via a lifting spindle and to which pressure medium is supplied via a valve for the purpose of exerting a high force. In this known drive device, high reaction forces act on the lifting spindle. This is avoided if, according to the invention, the hydraulic unit is a force intensifier with two pistons movable in relation to one another and differing from one another in the size of their active surfaces and has an intermediate part which, together with the pistons, encloses a pressure space filled with a pressure fluid, if the small piston having the smaller active surface is connected mechanically to the drive element, if, for the adjusting movement, the hydraulic unit can be moved as a whole, and if, for exerting a high force by means of the large piston having the larger active surface, the intermediate part can be blocked against displacement in relation to a fixed stand.
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