Patent ID: 7850647
Filing Date: 2010-12-14
Classification: A61M,G05B,H02H,Y02B,Y04S

Abstract:
1. A syringe comprising an outer barrel having first and second ends, an inner barrel slidable longitudinally within said outer barrel and adapted to support a needle at one end thereof, which needle projects through an aperture in said first end of said outer barrel and is in fluid communication with a fluid retaining chamber of said inner barrel, a piston within said chamber and actuable to draw fluid into said chamber and expel fluid from said chamber via said needle, a plunger connected to said piston and extending out from the other end of said inner barrel and the second end of said outer barrel, said outer barrel having retaining means on the inner wall surface thereof and said inner barrel having first and second spaced latching means for respectively engaging said retaining means and latching said inner barrel in either of two positions relative to said outer barrel, a first position wherein said needle projects from said outer barrel and is in a useable position, and a second position wherein said needle is fully retracted within said outer barrel, biasing means for biasing said inner barrel towards said second position and said plunger having means thereon to disengage said first latching means from said retaining means when said plunger is fully depressed whereby said inner barrel is able to move to said second position wherein said second latching means engages said retaining means and prevents further relative movement between said inner and outer barrels, and wherein a limit catch is provided on said plunger, said limit catch preventing said plunger from being fully depressed and disengaging said first latching means from said retaining means on initial actuation of said plunger but allowing said plunger to be depressed sufficiently to disengage said first latching means on the next plunger depression; wherein said inner barrel projects substantially from the second end of said outer barrel when in said second position; wherein said first latching means comprises an annular protrusion adjacent said other end of said inner barrel, said protrusion being located within a tapered groove in the outer surface of the inner barrel and being adapted for engagement with said retaining means; wherein said second latching means comprises an annular step at said one end of said inner barrel, in combination with a second annular protrusion spaced a short distance therefrom, said second annular protrusion having an outer diameter greater than the outer diameter of the remainder of the inner barrel; wherein said retaining means comprises at least one pair of opposed flexible fingers extending in a longitudinal direction of said outer barrel and having a space therebetween for accommodating said annular protrusion, said fingers being inclined inwardly at their adjacent extremities in their normal state, so as to enter said tapered groove and engage said annular protrusion; wherein said retaining means are provided on an insert which is permanently retained in the second end of said outer barrel and forms part of said outer barrel.