Patent ID: 7051403

Claim:
An electromechanical swing leaf operator comprising: a housing; a piston guided in said housing between a closing position and an opening position along a center longitudinal axis, said piston moving in a closing direction toward said closing position and in an opening direction toward said opening position, said piston having a toothed rack having teeth arranged on an S-shaped rolling curve with a gradient which increases from the closing position up to approximately half the length of the rack and subsequently decreases, each said tooth having a closing side tooth profile and an opening side tooth profile having different flank angles, the opening side flank angle of the teeth increasing up to approximately half the length of the toothed rack and subsequently being substantially constant or decreasing, the closing side flank angle of the teeth decreasing up to approximately half the length of the toothed rack and subsequently increasing, the closing side tooth profile of the last teeth in the opening direction executed with an increased flank angle, the teeth having a width which increases up to approximately half the length of the toothed rack and subsequently decreases; a spring urging said piston in the closing direction; a toothed pinion supported for rotation about a rotary axis in said housing and having teeth which mesh with the teeth of said rack, said pinion being eccentrically mounted and having a center point which, in the closing position, is offset from the rotary axis toward the toothed rack and, in the opening position, is offset from the rotary axis away from the toothed rack, said pinion rotating through more than 180 degrees from the closing position to the opening position, said pinion having a portion exceeding said 180 degrees which engages said last teeth in the opening direction of said rack; an electric motor which drives said pinion via a gear; and a control valve arrangement which reduces the closing speed of the piston as the piston moves toward said closing position, wherein said control valve arrangement comprises a first control valve and a second control valve, said piston being moved in said closing direction in four phases comprising: a first closing phase between approximately 180 degrees and 100 degrees wherein said piston moves with a constant closing speed controlled by said first control valve; a second closing phase between approximately 100 degrees and 70 degrees wherein the functioning of said first and second control valves is cancelled; a third closing phase between approximately 70 degrees and 20 degrees wherein said piston moves with said constant closing speed controlled by said first control valve; and a fourth closing phase between approximately 20 degrees and zero degrees controlled by said second control valve.