Patent ID: 7819845
Filing Date: 2010-10-26
Classification: A61M

Abstract:
1. A plunger jacket for an associated syringe having a plunger defining a central axis, comprising: a plunger jacket body at least partially covering the plunger and having a front conical surface forming a first apex and an intermediate conical surface forming a second apex wherein said first apex and said second apex lie on the central axis, wherein the front conical surface defines a first opening angle with respect to the central axis and the intermediate conical surface defines a second opening angle with respect to the central axis, wherein said first opening angle is greater than said second opening angle such that said front conical surface and said intermediate conical surface form a front wall of the plunger jacket having a thickness that increases in the axial direction as said front conical surface and said intermediate conical surface extend radially outward; wherein the plunger jacket has a forwardmost sealing ring and a rearwardmost sealing ring each protruding from the plunger body in a resting state, wherein said rearwardmost sealing ring protrudes from said plunger body near the intersection of a line corresponding to said intermediate conical surface and an exterior of the plunger body, wherein a resultant force extending generally along said line of said intermediate conical surface causes an outer diameter of only the rearwardmost sealing ring to increase when said plunger jacket is driven forward; and, wherein an outer diameter of the forward-most sealing ring in the resting state is substantially the same as the outer diameter of the rearwardmost sealing ring in the resting state, wherein said forwardmost sealing ring and said rearward-most sealing ring are separated by a space, said forwardmost sealing ring being adapted to sealingly engage the syringe in the resting state, while said space is unsealed at said rearward-most sealing ring when in the resting state to allow sterilization fluid to flow into the space between said forwardmost sealing ring and said rearwardmost sealing ring when the plunger jacket is in said resting state.