Patent ID: 7124581

Claim:
A drive mechanism, particularly for a movable component ( 10 , 66 ) of a closing unit, an injection unit or ejector unit of a plastics injection molding machine, comprising an output element ( 54 ) movable in a straight line and an electric-motor drive unit ( 50 ) having an electric motor ( 51 ), and at least a first piston-cylinder unit ( 12 ), which has a first cylinder housing ( 13 ) and a first hydraulic piston ( 14 ) which, with a first active surface ( 18 , 19 ), bounds a first cylinder chamber ( 16 , 17 ) filled with pressurized liquid and lies in a force chain between the output element ( 54 ) of the electric-motor drive unit ( 50 ) and movable component ( 10 , 66 ), a second piston-cylinder unit ( 24 ), which has a second cylinder housing ( 26 ) and a second hydraulic piston ( 27 ) which, with a second active surface ( 31 , 32 ), bounds a second cylinder chamber ( 29 , 30 ) filled with pressurized liquid, a third piston-cylinder unit ( 25 ), which has a third cylinder housing ( 36 ) and a third hydraulic piston ( 37 ) which, with a third active surface ( 41 , 42 ) bounds a third cylinder chamber ( 39 , 40 ) filled with pressurized liquid and whose active surface ( 41 , 42 ) is substantially smaller than the first active surface ( 18 , 19 ) and the second active surface ( 31 , 32 ), a fluidic connection between the first cylinder chamber ( 16 , 17 ) and the second cylinder chamber ( 29 , 30 ) is controlable via a valve ( 43 ), and wherein when the valve ( 43 ) is open, the second hydraulic piston ( 27 ) is movable by the electric motor ( 51 ) via the output element ( 54 ) for an actuating movement of the movable component ( 10 , 66 ) with effect of displacing pressurized liquid out of the second cylinder chamber ( 29 , 30 ) into the first cylinder chamber ( 16 , 17 ) and, to exert a high force on the movable component ( 10 , 66 ), when the valve ( 43 ) is closed, the third hydraulic piston ( 37 ) is displacable with effect of displacing pressurized liquid out of the third cylinder chamber ( 39 , 40 ) into the first cylinder chamber ( 16 , 17 ).