US 12,109,399 B2
Plunger rod and assembly having modified thread geometry
James Thompson, Reading, PA (US); Lauren Shafer Greenberg, Barto, PA (US); and Matthew Dylan Sweeney, West Chester, PA (US)
Assigned to West Pharmaceutical Services, Inc., Exton, PA (US)
Appl. No. 16/973,830
Filed by West Pharmaceutical Services, Inc., Exton, PA (US)
PCT Filed Jun. 21, 2019, PCT No. PCT/US2019/038514
§ 371(c)(1), (2) Date Dec. 10, 2020,
PCT Pub. No. WO2019/246543, PCT Pub. Date Dec. 26, 2019.
Claims priority of provisional application 62/687,992, filed on Jun. 21, 2018.
Prior Publication US 2021/0252228 A1, Aug. 19, 2021
Int. Cl. A61M 5/315 (2006.01); A61L 2/18 (2006.01)
CPC A61M 5/31515 (2013.01) [A61L 2/18 (2013.01); A61L 2202/23 (2013.01); A61M 2005/31516 (2013.01); A61M 2205/02 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A plunger assembly comprising:
a piston comprising an inner piston surface, a female thread, an outer surface that faces outwardly relative to a longitudinal axis of the piston, and a proximal-facing piston surface extending radially inwardly from the outer surface, wherein the inner piston surface and the female thread define an inner piston cavity; and
a plunger rod comprising an outer surface that faces outwardly relative to a longitudinal axis of the plunger rod, a distal-facing rod surface extending radially inwardly from the outer surface of the plunger rod, and a threaded extension that extends a length distally from the distal-facing rod surface, wherein:
the threaded extension is configured to threadedly engage with the female thread along at least a portion of the length,
the threaded extension and the inner piston surface define a ventilation space when the plunger rod is fully advanced distally relative to the piston,
the proximal-facing piston surface and the distal-facing rod surface, when the plunger rod is fully advanced distally relative to the piston, are spaced apart and define a fluid passageway therebetween,
the fluid passageway extends from outside of the plunger assembly into the inner piston cavity,
the fluid passageway comprises an inlet that fluidly connects the fluid passageway to outside of the plunger assembly, and
the inlet of the fluid passageway is defined by a space between an edge of the proximal-facing piston surface that intersects with the outer surface of the piston and an edge of the distal-facing rod surface that intersects with the outer surface of the plunger rod.