Vacuum belt conveyor

A vacuum conveyor apparatus for transferring selected vertically-arranged containers which are in a random mass configuration at a first station to a second station spaced from said first station, said apparatus comprising:

• a single vacuum plenum having a wall, with an inner surface and an outer surface, spaced above said first station a distance slightly greater than the height of the containers and extending to said second station;
• a fan for drawing a constant maximum vacuum in said plenum which is uniform from said first station to said second station;
• a first set of multiple rows of parallel transfer slots through said plenum wall extending from said upstream end to said downstream end of said plenum wall, said rows being spaced across said plenum wall;
• a second set of multiple rows of shorter pickup slots through said plenum wall interlayed alternately between said rows of transfer slots and extending from said upstream end a short equal incremental distance along said plenum wall toward said downstream end;
• a transfer belt having a reach, with a smooth outer surface, mounted for movement along said outer surface of said plenum wall, said belt having a plurality of equally spaced openings arranged in longitudinal parallel and lateral parallel rows, said longitudinal rows corresponding to and overlaying all of said rows of slots in said first and second set of multiple rows, so that a greater number of openings are effective to draw a first greater CFM which is sufficient to lift and hold each of the articles against said transfer belt at said first station and a lesser number of openings are effective to draw a second lesser CFM downstream from the ends of said pickup slots which is just sufficient to continue to hold and transfer the articles to said second station;
• said openings being sized and positioned so that said fan draws the maximum vacuum in said plenum of which it is capable when all of said openings are uncovered so that said maximum vacuum draws air at said greater desired CFM, which is just sufficient to pickup only properly oriented containers at said first station;
• and
• means turning said fan at a constant RPM which causes said fan to draw the maximum vacuum in said plenum of which said fan is capable when all of said openings are uncovered.