Binary needle attachment mechanisms

Abstract

A syringe and detachable needle assembly having binary attachment features include an elongate syringe barrel having a longitudinal axis, an open proximal end and an open distal end including a collar. The collar includes the cylindrically shaped sidewall having an inside surface and an outside surface. A needle assembly includes the hub having a body portion including a proximal end, a distal end and a conduit therethrough. A cannula having a distal end, a proximal end and a lumen therethrough is attached to the distal end of the hub so that the lumen is in fluid communication with the chamber. A lug is provided on one of the collar and the hub and a ramp and a rest surface is provided on the other of the collar and the hub. The ramp is oriented at an acute angle with respect to longitudinal axis for guiding the lug during needle assembly attachment, to the rest surface forcing the hub to contact the barrel to form a seal the hub and the barrel.

1 . A syringe and detachable needle assembly having binary attachment features comprising:
 an elongate syringe barrel having a longitudinal axis, an inside surface defining a chamber for retaining fluid, an open proximal end, an open distal end including a collar, a portion of said collar including a cylindrically shaped sidewall having an inside surface and an outside surface;   a needle assembly including a hub having a body portion including a proximal end, a distal end, a conduit therethrough, said needle assembly further including a cannula having a distal end, a proximal end and a lumen therethrough, said proximal end of said cannula being connected to said distal end of said hub so that said lumen is in fluid communication with said chamber; and   a lug on one of said collar and said hub, and a ramp and a rest surface on the other said collar and said hub, said ramp oriented at an acute angle with respect to said longitudinal axis for guiding said lug, during needle assembly attachment, to said rest surface forcing said hub to contact said barrel to form a seal between said hub and said barrel, said rotation of said hub with respect to said barrel being less than 180° while said lug travels along said ramp during installation of said needle assembly to said barrel.   
     
     
         2 . The syringe assembly of  claim 1  further including a distally facing annular surface projecting inwardly into said open proximal end of said barrel and a proximally facing annular surface on said body portion of said hub contacting said distally facing annular surface to form a seal between said hub and said barrel. 
     
     
         3 . The syringe assembly of  claim 2  wherein said proximally facing annular surface on said body portion of said hub is a flexible skirt. 
     
     
         4 . The syringe assembly of  claim 1  wherein said hub is loosely retained by said barrel during most of the travel of said lug along said ramp so that said syringe and said needle assembly are incapable of injecting fluids without leaking fluid outside said lumen while said hub is loosely retained. 
     
     
         5 . The syringe assembly of  claim 1  further including a discontinuity between said ramp and said rest surface for providing additional tactile feedback to the user during rotation of said needle assembly with respect to said barrel as said lug transitions from said ramp to said rest surface. 
     
     
         6 . The syringe assembly of  claim 5  wherein said discontinuity provides additional resistance to the movement of said lug as it transitions from said ramp to said rest surface. 
     
     
         7 . The syringe assembly of  claim 5  wherein said discontinuity increases the length of said ramp so that said lug moves slightly farther proximally with respect to said collar before falling back onto said rest surface. 
     
     
         8 . The syringe assembly of  claim 1  further including a projection on said hub configured for contacting a protuberance on said collar for providing additional tactile feedback to the user during rotation of said needle assembly with respect to said barrel as said lug transitions from said ramp to said rest surface. 
     
     
         9 . The syringe assembly of  claim 1  wherein said lug includes four lugs and said ramp includes two ramps and said rest surface includes two rest surfaces. 
     
     
         10 . The syringe assembly of  claim 1  wherein said rotation of said hub with respect to said barrel is less than 100° while said lug travels along said ramp during installation of said needle assembly to said barrel. 
     
     
         11 . The syringe assembly of  claim 1  wherein said lug projects outwardly from said body portion of said hub and said ramp is on said inside surface of said sidewall. 
     
     
         12 . The syringe assembly of  claim 11  wherein said rest surface includes a portion of the periphery an aperture through said sidewall. 
     
     
         13 . The syringe assembly of  claim 1  wherein said lug projects inwardly from said body portion of said hub and said ramp is formed on said outside surface of said sidewall. 
     
     
         14 . The syringe assembly of  claim 1  wherein said lug projects inwardly from said inside surface of said sidewall and said ramp is formed on said body portion of said hub. 
     
     
         15 . The syringe assembly of  claim 1  wherein said lug projects outwardly from said outside surface of said sidewall and said ramp is formed inside said body portion of said hub. 
     
     
         16 . The syringe assembly of  claim 1  further including an outwardly projecting annular sealing ring on said body portion of said hub for sealingly engaging said sidewall of said collar to form a secondary seal between said hub and said barrel. 
     
     
         17 . The syringe assembly of  claim 16  wherein said annular sealing ring is an elastomeric o-ring. 
     
     
         18 . The syringe assembly of  claim 16  wherein said annular sealing ring is a tapered projection having a base adjacent to said body portion and a free end, said tapered projection being wider at said base than at said free end. 
     
     
         19 . The syringe assembly of  claim 16  wherein said annular sealing ring is integrally formed with said body portion. 
     
     
         20 . The syringe assembly of  claim 1  further including an elongate plunger rod having a proximal end, a distal end and a stopper at said distal end of said plunger rod, said stopper being slidably positioned in fluid tight engagement with said inside surface of said barrel for displacing fluid from said chamber through said cannula by relative motion of said plunger rod with respect to said barrel. 
     
     
         21 . The syringe assembly of  claim 20  wherein said stopper includes a distally facing projection for partially occluding said conduit in said hub when said stopper is in its distal most position inside said barrel. 
     
     
         22 . The syringe assembly of  claim 1  further including an elongate hollow needle shield having a distal end and an open proximal end removably engaged to said hub so that said needle shield covers said cannula. 
     
     
         23 . The syringe assembly of  claim 1  wherein said hub and said cannula are integrally formed of thermoplastic material. 
     
     
         24 . The syringe assembly of  claim 1  wherein said cannula includes a blunt distal tip. 
     
     
         25 . A syringe and detachable needle assembly having binary attachment features comprising:
 a elongate syringe barrel having a longitudinal axis, and inside surface defining a chamber for retaining fluid, an open proximal end, an open distal end including a collar and a distally facing annular surface projecting inwardly into said open proximal end, a portion of said collar including a cylindrically shaped sidewall having an inside surface and an outside surface;   a needle assembly including a hub having a body portion including a proximal end, a distal end, a conduit therethrough, a proximally facing annular surface on said body portion contacting said annular surface of said barrel forming a seal between said hub and said barrel, said needle assembly further including a cannula having a distal end, a proximal end and a lumen therethrough, said proximal end of said cannula being connected to said distal end of said hub so that said lumen is in fluid communication with said chamber;   two lugs projecting outwardly from said body portion of said hub and two ramps on said inside surface of said collar having a rest surface at a proximal end of each ramp, said ramps oriented at an acute angle with respect to said longitudinal axis for guiding said lugs, during attachment of said needle assembly to said barrel, to said rest surfaces forcing said annular surface on said hub to contact said annular surface on said barrel to form said seal between said hub and said barrel, said rotation of said hub with respect to said barrel being less than 100° while said lug travels along said ramp during installation of said needle assembly, during said travel said hub being loosely retained by said barrel; and   an elongate plunger rod having a proximal end, a distal end and a stopper at said distal end of said plunger rod, said stopper being slidably positioned in fluid tight engagement with said inside surface of said barrel for displacing fluid from said chamber through said cannula by relative motion of said plunger rod with respect to said barrel.   
     
     
         26 . The syringe assembly of  claim 25  wherein said two lugs include four lugs and said inside surface of said collar including a guide surface running along and spaced from each ramp for guiding said lugs during removal of said needle assembly from said barrel. 
     
     
         27 . The syringe assembly of  claim 25  further including an outwardly projecting annular sealing ring on said body portion of said hub for sealingly engaging said sidewall of said collar to form a secondary seal between said hub and said barrel. 
     
     
         28 . The syringe assembly of  claim 25  further including a discontinuity between at least one said ramps and its rest surface for providing additional tactile feedback to the user during rotation of said needle assembly with respect to said barrel as said lug transitions from said ramp to said rest surface. 
     
     
         29 . The syringe assembly of  claim 25  further including a projection on said hub configured for contacting a protuberance on said collar for providing additional tactile feedback to the user during rotation of said needle assembly with respect to said barrel as said lug transitions from said ramp to said rest surface. 
     
     
         30 . A syringe and detachable hub having binary attachment features comprising:
 an elongate syringe barrel having a longitudinal axis, an inside surface defining a chamber for retaining fluid, an open proximal end, an open distal end including a collar, a portion of said collar including a cylindrically shaped sidewall having an inside surface and an outside surface;   a hub having a body portion including a proximal end and a distal end; and   a lug on one of said collar and said hub, and a ramp and a rest surface on the other said collar and said hub, said ramp oriented at an acute angle with respect to said longitudinal axis for guiding said lug, during hub attachment, to said rest surface forcing said hub to contact said barrel to form a seal between said hub and said barrel, said rotation of said hub with respect to said barrel being less than 180° while said lug travels along said ramp during installation of said hub to said barrel.   
     
     
         31 . The syringe assembly of  claim 30  further including said hub having a conduit therethrough; and
 a cannula having a distal end, a proximal end and a lumen therethrough, said proximal end of said cannula being connected to said distal end of said hub so that said lumen is in fluid communication with said chamber.   
     
     
         32 . A method of making an elongate syringe barrel for use with a needle assembly having a hub, said hub including a body portion having an outwardly projecting lug and a proximally facing annular surface, said barrel having a longitudinal axis, an outside surface and an inside surface defining a chamber for retaining fluid, an open proximal end, and open distal end including a collar and a distally facing annular surface projecting into said open proximal end, a portion of said collar including a cylindrically shaped sidewall having an inside surface and an outside surface, a ramp and a rest surface projecting inwardly from said inside surface, said ramp oriented at an acute angle with respect to said longitudinal axis for guiding said lug, during needle assembly attachment, to said rest surface forcing said annular surface on said hub to contact said annular surface in said open proximal end of said barrel, to form a seal between said hub and said barrel, said rotation of said hub with respect to said barrel being less than 180° while said lug travels along said ramp during installation of said needle assembly to said barrel, said method comprising the steps of:
 providing an injection mold having a cavity defining a syringe barrel, said mold including a fixed portion defining said outside surface of said barrel, a proximal core pin defining said chamber, a movable split cavity defining the outside surface of said collar and including a raised projection for forming an aperture in said collar, said ramp and said rest surface, and a distal core pin defining the remaining portions of the interior of said collar and contacting said raised projection on said split cavity;   injecting molten thermoplastic material into said cavity of said mold;   allowing enough time for said thermoplastic material to solidify enough to allow movement of said barrel with respect to said mold cavity;   opening said split cavity so that said raised projection is outside of said collar;   removing said proximal core pin and said barrel axially from said fixed portion of said mold without rotation of said distal core pin.   
     
     
         33 . The method of  claim 32  wherein said thermoplastic material is selected from the group consisting of polypropylene, polyethylene, polycarbonate, PET and combinations thereof. 
     
     
         34 . The method of  claim 32  wherein said raised projection on said split cavity is further configured to cooperate with said distal core pin to form a guide surface running along and spaced from said ramp for guiding said lug during removal of said needle assembly from said barrel. 
     
     
         35 . The method of  claim 32  wherein said split cavity includes a second projection, and said core pin is configured to cooperate with said second projection to form a second aperture in said collar and a second rest surface.