Patent ID: 9642970
Date: 2017-05-09
CPC Classifications: A61M

Claim:
1. A syringe comprising a barrel, a rearwardly biased needle retraction assembly disposed forwardly in the barrel, and a plunger assembly slidably engaging the barrel to define a fluid chamber disposed between the needle retraction assembly and the plunger assembly; the plunger assembly further comprising a plunger having a tubular body with a front tip defining an opening into a retraction cavity disposed inside the tubular body, and an elastomeric plunger seal disposed over and around the front tip and the opening; the elastomeric plunger seal further comprising an annular body portion that provides a fluid seal against the barrel and a transverse web portion that covers the opening into the retraction cavity; the barrel and the plunger assembly being cooperatively configured so that the annular body portion of the elastomeric plunger seal is pushed rearwardly on the tubular body of the plunger as the plunger is moved forwardly relative to the barrel prior to initiating needle retraction, thereby displacing and repositioning the annular body portion relative to the tubular body, and stretching and thinning the transverse web portion so that the transverse web portion is more easily ruptured by a rearwardly extending portion of the needle retraction assembly and contracts following rupture to a position outside the opening that does not block the opening into the retraction cavity.