Patent ID: 7309089

Claim:
A vacuum cup for a material handling system, said vacuum cup being adapted for engaging and picking up an object, said vacuum cup comprising: a body portion having a generally central axis; a flexible perimeter seal extending from said body portion and circumferentially around said generally central axis, said perimeter seal defining a first engaging plane at a first level when said vacuum cup is not engaged with an object, said perimeter seal engaging an object and substantially sealing to the object when said vacuum cup is engaged with the object, said vacuum cup being substantially retained against the object via a partial vacuum within a cavity defined between said body portion, said perimeter seal and the object; a relief port defined through one of said body portion and said flexible perimeter seal of said vacuum cup, said relief port being radially offset from said generally central axis of said body portion, said relief port having a sealing member, said sealing member defining a second engaging plane at a second level when said vacuum cup is not engaged with an object, said second level being above said first level and between said first level and said body portion; said vacuum cup being configured so that said sealing member at least substantially closes said relief port to limit airflow therethrough when said sealing member engages the object; and said sealing member at least partially disengaging from the object and at least partially opening said relief port when said vacuum cup is moved relative to the object and moved a sufficient amount in a direction generally away from the object and while said perimeter seal remains engaged with the object, said relief port at least partially relieving the partial vacuum in said cavity when said relief port is at least partially opened and while said perimeter seal is engaged with the object.