Patent ID: 7617955

Claim:
A liquid dispensing module for dispensing a viscous hot melt adhesive comprising: a dispenser body having a liquid inlet, a discharge outlet, and a flow channel capable of directing a flow of the hot melt adhesive from said liquid inlet to said discharge outlet, said flow channel including a valve seat between said liquid inlet and said discharge outlet; a needle defining a central axis and having a valve element mounted for reciprocating movement in said dispenser body between an open position in which said valve element is disengaged with said valve seat allowing hot melt adhesive flow from said discharge outlet and a closed position in which said valve element is engaged with said valve seat preventing hot melt adhesive flow from said discharge outlet; a needle guide mounted to said dispenser body and having a passage for receiving a portion of said needle, said needle adapted to move axially relative to said needle guide; a flexible seal having first and second opposed ends and a bulbous central portion disposed between said first and second ends, said first end coupled to said needle guide, said second end coupled to said needle and adapted to move with said needle, said central portion located a greater radial distance from said needle axis than said first and second ends to define an unfilled annular cavity between said seal and said needle, and said seal having a thickness along the central portion that is greater than a thickness of the seal along the first and second ends, said seal adapted to prevent hot melt adhesive from leaking out of said flow channel; and an actuator operatively coupled to said needle, said actuator capable of actuating said needle between the open and closed positions to selectively dispense hot melt adhesive from said discharge outlet.