Plastic injection molding nozzle with gas assist

An apparatus for injecting a viscous fluid into a mold cavity of a mold body, said apparatus comprising:

• a mold body including a core portion and a cover portion, defining between them a mold cavity;
• a nozzle body positioned adjacent said mold body, said nozzle body comprising an inlet end, a discharge end, which communicates with said mold cavity, and a flow passage for the viscous fluid extending from said inlet end to said discharge end;
• a valve element mounted for reciprocation in said nozzle body flow passage to control a flow of the viscous fluid through said nozzle body discharge end wherein said valve element comprises a barrel having a first end, adapted to selectively engage a portion of said tip section to prevent a flow of the viscous fluid therepast, and a second end, and wherein a bore extends longitudinally in said barrel wherein said valve element further comprises:
• a cross link bar oriented generally normal to a longitudinal axis of said barrel and secured thereto, and
• an actuator mechanism operatively connected to said cross link bar;
• a pin which is mounted in said bore such that said pin remains stationary while said barrel reciprocates;
• a seal element encircling said pin and located adjacent said cross link bar for sealing said pin against said cross link bar;
• and,
• a flow passage defined between said pin and said valve element, said flow passage allowing a flow of a non-viscous fluid through said barrel and into said mold cavity.

A nozzle for injecting a viscous fluid and a non-viscous fluid, comprising:

• a nozzle body having an inlet end, a discharge end and a flow passage for the viscous fluid extending from said inlet end to said discharge end;
• a shut off barrel disposed for reciprocating movement in said nozzle body flow passage to control a flow of the viscous fluid through said nozzle body discharge end;
• a passage extending in said shut off barrel and terminating at a front end thereof;
• a pin mounted on said shut off barrel passage so as to remain stationary when said shut off barrel reciprocates, wherein said pin includes a front end which extends toward said nozzle body discharge end at least as far as a front end of said barrel when said barrel is in a retracted position;
• and,
• a flow passage defined between said pin and said barrel through which a non-viscous fluid can flow at all positions of said barrel.