Patent ID: 8333307

Claim:
A liquid dispensing module for dispensing a viscous liquid comprising: a dispenser body assembly including a liquid inlet, a discharge outlet, and a flow channel capable of directing a flow of the liquid from said liquid inlet to said discharge outlet, said flow channel including a valve seat between said liquid inlet and said discharge outlet; an actuator including an actuator chamber adapted to be in communication with a pressurized air source; a flexible seal including an upstream end sealingly engaging said dispenser body assembly and including a downstream end, said flexible seal adapted to seal said flow channel from said actuator; and a needle including a valve element and operable by said actuator for reciprocating movement in said dispenser body assembly between an open position in which said valve element is disengaged with said valve seat allowing liquid flow from said discharge outlet and a closed position in which said valve element is engaged with said valve seat preventing liquid flow from said discharge outlet, said needle including an enlarged portion engaging and retaining said downstream end of said flexible seal to allow reciprocating movement of said downstream end with said needle and to place said flexible seal in lengthwise compression between said upstream and downstream ends, wherein said flexible seal further includes a central portion between said upstream and downstream ends and extending radially outwardly from said needle to form an interior cavity between said central portion and said needle, and said interior cavity is in fluid communication with said actuator chamber to allow air pressurization of said interior cavity for preventing said central portion from collapsing onto said needle.