US20080033370A1 - Binary needle attachment mechanisms - Google Patents

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.

Description

FIELD OF THE INVENTION
• The present invention relates to syringes with removable needle assemblies. More particularly, the present invention relates to syringes having binary attachment features, and a method of making a syringe barrel for the present invention.
BACKGROUND
• Syringe assemblies designed for use with replaceable needle assemblies usually contain a luer slip or locking luer type fitting for securing the needle assembly to the syringe barrel. These connections rely on an elongate frusto-conically shaped syringe barrel tip which frictionally engages a frusto-conically shaped passageway in a needle hub. The relatively acute angle of the syringe tip, measured from the longitudinal axis of the syringe barrel, provides an excellent seal between the syringe tip and the hub. However, slight variations in the angle or diameter of the tapered surfaces of the syringe barrel and/or the needle hub produce large variations in the relative position of the needle hub with respect to the end of the barrel and, therefore, variations in dead space. The space inside the barrel tip and between the end of the barrel tip and the end of the cavity in the hub constitutes a dead space containing liquid that cannot be delivered by the syringe.
• In the case of expensive medications and multi-patient immunization programs, medication lost in the dead space can become costly. This is especially true in immunization programs involving thousands of people. Controlling dead space to a minimum may result in more people being immunized with the same amount of medication provided for the program.
• The prior art also teaches a flat seal, perpendicular to the longitudinal axis of the syringe barrel which mates with a complimentary flat seal on the needle hub for use with a threaded needle assembly and barrel engagement structure. The flat seal reduces the portion of dead space attributable to variations and barrel and hub tolerances. However, unlike the locking luer type fittings that become tighter as additional torque is applied to the needle hub, syringe assemblies having flat and low angle seals reach a sealed condition in a rather abrupt fashion due to their geometry.
• When syringes and needle assemblies of any of the above-mentioned geometries are assembled in the manufacturing facility, the needle assembly can be attached to the syringe barrel using an optimal amount of torque applied to the needle hub therefore avoiding needle hubs that are not properly attached which can lead to leaking of medication and needle hubs which are over tightened which can have long term consequences due to creep in the plastic components which relax over time and lose their preload. However, in a clinical setting the attaching of a needle assembly to a syringe barrel is not done with the consistent controlled force found in the manufacturing process. Some users of the syringe and needle assembly are strong, some are weak and many have their own preconceived opinion regarding what the proper torque needed to attach a needle assembly.
• Although the prior art teaches many syringe barrel and needle hub connecting structures, there is still a need for a low dead space syringe which will not attach the needle assembly to the syringe barrel unless an adequate amount of torque is applied to the needle hub and which will not tighten further after proper installation has occurred.
SUMMARY OF THE INVENTION
• A syringe and detachable needle assembly having binary attachment features includes an elongate syringe barrel having a longitudinal axis, an inside surface defining the chamber for retaining fluid, an open proximal end and an open distal end including a collar. A portion of the collar includes a cylindrically shaped sidewall having an inside surface and an outside surface. A needle assembly includes a hub having a body portion including a proximal end, a distal end and a conduit therethrough. The needle assembly further includes a cannula having a distal end, a proximal end and a lumen therethrough. The proximal end of the cannula is connected to the distal end of the hub so that the lumen is in fluid communication with the chamber in the barrel. A lug on one of said collar and said hub, and a ramp and a rest surface on the other of said collar and said hub. The ramp is oriented at an acute angle with respect to the 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 between the hub and the barrel. Rotation of the hub with respect to the barrel is less than 180° when the lug travels along the ramp during installation of needle assembly to the barrel.
• The syringe assembly may further include a distally facing annular surface projecting inwardly from the open proximal end of the barrel and a proximally facing annular surface on the body portion of the hub contacting the distally facing annular surface to form a seal between the hub and the barrel.
• The proximally facing annular surface on the hub may be in the form of a flexible annular skirt.
• The hub is preferably loosely retained by the barrel during most of the travel of the lug along the ramp so that during this time the hub is not sealed to the barrel and an attempt to remove the needle shield in an axial direction will cause the hub to become disconnected from the barrel.
• The syringe assembly may include a discontinuity between the ramp and the rest surface for providing additional tactile feedback to the user during rotation of the needle assembly with respect to the barrel as the lug transitions from the ramp to the rest surface. The discontinuity may provide additional resistance to the movement of the lug as it transitions from the ramp to the rest surface. The discontinuity may also increase the length of the ramp so that the lug moves slightly farther proximally with respect to the collar before falling back onto the rest surface.
• The syringe assembly may include a projection on the hub configured for contacting a protuberance on the collar for providing additional tactile feedback to the user during rotation of the needle assembly with respect to the barrel as said lug transitions from said ramp to said rest surface.
• The syringe assembly of the present invention is preferably configured so that the hub is loosely retained by the barrel during most of the travel of the lug along the ramp so that an attempt to remove the needle shield in an axial direction results in the hub becoming disconnected from the barrel.
• The syringe assembly may include four lugs and the ramp may include two ramps with two rest surfaces. It is also desirable to have rest surfaces without ramps, e.g., two opposed ramps with rest surfaces and two opposed rest surfaces without ramps.
• The syringe assembly is preferably configured so that the rotation of the hub with respect to the barrel is less than 100° while the lug travels along the ramp during installation of the needle assembly to the barrel.
• The body portion of the hub may also include an outwardly projecting annular sealing ring for sealing engaging the sidewall of the collar to form a seal between the hub and barrel. The sealing ring may take the form of an elastomeric o-ring. The annular sealing ring may be integrally formed with the body portion of the hub. Further, the annular sealing ring may be configured to be a tapered projection having a base adjacent to the body portion of the hub and a free-end wherein the tapered projection is wider at its base than at its free-end.
• The syringe assembly may further include an elongate plunger rod having a proximal end, a distal end and a stopper at the distal end slidably positioned in fluid tight engagement with the inside surface of the barrel for displacing fluid from the chamber through the cannula by relative motion of the plunger rod with respect to the barrel. The stopper may also include a distally facing projection for the partially occluding the conduit in the needle hub when the stopper is in its distal most position inside the barrel.
• The needle assembly may also include an elongate hollowed needle shield having a distal end and an open proximal end removably engaging the hub so that the needle covers the cannula.
• The cannula may be integrally formed with the hub using thermoplastic material. Further the cannula may have a sharp or a blunt tip.
• The syringe assembly of the present invention may be configured so that a lug projects outwardly from the body portion of the hub and a ramp is in the inside surface of the sidewall of the barrel collar.
• The syringe assembly may be configured so that a lug projects inwardly from the body portion of the hub and a ramp is formed on the outside surface of the sidewall of the collar of the barrel.
• The syringe assembly may be configured so that the lug projects inwardly from the inside surface of the sidewall of the collar and the ramp is formed on the exterior of the body portion of the hub.
• The syringe assembly may be configured so that a lug projects outwardly from the outside surface of the sidewall of the collar of the barrel and a ramp is formed on the inside of the body portion of the hub.
• A rest surface may include a portion of the periphery of an aperture through the sidewall of the barrel collar.
• Another embodiment of the present invention includes a syringe and detachable hub having binary attachment features including 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, and a portion of the collar including a cylindrically shaped sidewall having an inside surface and an outside surface. A hub has a body portion including a proximal end and a distal end. A lug on one of the collar or the hub, and a ramp and a rest surface on the other of the collar or the hub are provided. The ramp is oriented at an acute angle with respect to the longitudinal axis for guiding the lug, during hub attachment, to the rest surface forcing the hub to contact the barrel to form a seal between the seal between the hub and the barrel. The rotation of the hub with respect to the barrel is desirably less than 180° and preferably less than 100° while the lug travels along the ramp during installation of the hub to the barrel. It is not necessary that the hub have a conduit therethrough in fluid communication with the chamber in the barrel. The hub without a conduit therethrough or with an occluded conduit can function as a cap to seal medication in the syringe assembly of the present invention before the time of use. Also, the syringe of the present invention can be used with the needle assembly for filling the syringe with medication using an appropriately sized cannula. After filling, the cannula is discarded and a hub, without a conduit, is attached to the distal end of the barrel to seal in and protect the medication. At the time of use, the hub is removed and a needle assembly having a cannula, appropriately sized for injection, is attached to the barrel.
• The present invention also includes a method of making an elongate syringe barrel for use with a needle assembly having a hub wherein the hub includes a body portion having an outwardly projecting lug and a proximally facing annular surface. The barrel includes a longitudinal axis, an outside surface and an 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 into the open proximal end. A portion of the collar includes a cylindrically shaped sidewall having an inside surface and an outside surface. A ramp and a rest surface project inwardly from the inside surface of the collar. The ramp is oriented at an acute angle with respect to the longitudinal axis for guiding the lug, during needle attachment, to the rest surface forcing the annular surface on the hub to contact the annular surface in the open proximal end of the barrel to form a seal between the hub and the barrel. The rotation of the hub with respect to the barrel is desirably less than 180° and preferably less than 100° while the lug travels along the ramp during installation of needle assembly to the barrel. The method of molding comprises the steps of: providing an injection mold having a cavity defining a syringe barrel. The mold includes a fixed portion defining the outside surface of the barrel, a proximal core pin defining the chamber in the barrel, a split cavity defining the outside surface of the collar and including a raised projection for forming an aperture in the collar, the ramp and the rest surface, and a straight-pulled distal core pin defining the remaining portions of the interior of the collar. The distal core pin contacts the raised surface on the split cavity when the mold is closed. The method further includes injecting molten thermoplastic material into the cavity of the mold; allowing enough time for the thermoplastic material to solidify enough to allow movement of the barrel with respect to the mold; opening the split cavity so that the raised projection is outside of the collar; and removing the proximal core pin and the barrel axially from the fixed portion of the mold without rotation of the distal core pin.
• The method of the present invention further including the raised projection on the split cavity being further configured to cooperate with the distal core pin to form a guide surface running along and spaced from the ramp, for guiding the lug during removal of the needle assembly from the barrel.
• A method of the present invention may further include the split cavity having a second projection and the core pin is configured to cooperate with the second projection of the split cavity to form an additional aperture in the collar and an additional rest surface. Distal core pin is configured for defining the remaining portions of the additional rest surface. The additional rest surface does not have a ramp for guiding a lug connected to it.
• The method is preferably carried out with thermoplastic materials selected from the group consisting of polypropylene, polyethylene, polycarbonate, PET and combinations thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is an exploded perspective view of a prior art needle assembly and syringe.
• FIG. 2 is an enlarged cross-sectional view of the distal end of the syringe barrel ofFIG. 1.
• FIG. 3 is a partial cross-sectional view showing a needle assembly ofFIG. 1 attached to the syringe barrel ofFIG. 1.
• FIG. 4 is a perspective view of a syringe and removable needle assembly of the present invention.
• FIG. 5 is an exploded perspective view of the components of the syringe assembly ofFIG. 4.
• FIG. 6 is a side-elevational view of the hub of the needle assembly.
• FIG. 7 is an enlarged cross-sectional view of the distal end of the syringe barrel ofFIG. 5.
• FIG. 8 is an enlarged cross-sectional view of the distal end of an alternative syringe barrel structure.
• FIG. 9 is a side-elevational view of alternative needle assembly of the present invention.
• FIG. 10 is a cross-sectional view of the distal end of a syringe barrel for use with the needle assembly ofFIG. 9.
• FIG. 11 is a side-elevational view of another alternative needle assembly of the present invention.
• FIG. 12 is a cross-sectional view of the needle assembly ofFIG. 11 attached to a syringe barrel.
• FIG. 13 is still another alternative needle assembly similar to the needle assembly ofFIG. 11.
• FIG. 14 is perspective view of the distal end of an alternative syringe barrel of the present invention.
• FIG. 15 is a perspective view of a needle hub for use with the syringe barrel ofFIG. 14.
• FIG. 16 is still another alternative needle assembly of the present invention.
• FIG. 17 is a cross-sectional view of the distal end of the syringe barrel for use with the needle assembly ofFIG. 16.
• FIG. 18 is still another alternative embodiment of the needle assembly and syringe of the present invention.
• FIG. 19 is a side-elevational view of the syringe barrel ofFIG. 18.
• FIG. 20 is a cross-sectional view of the prior art syringe barrel.
• FIG. 21 is a side elevation view of a threaded core used to mold the syringe barrel ofFIG. 20.
• FIG. 22 is a cross-sectional view of an injection mold used to practice the method of the present invention.
• FIG. 23 is an exploded view illustrating the distal end of the syringe barrel along with the stationery straight pull core pin and split core of the injection mold ofFIG. 22.
DETAILED DESCRIPTION
• While this invention is satisfied by embodiments in many different forms, there are shown in the drawings and will herein be described in detail, preferred embodiments of the invention with the understanding that the present disclosure is to be considered exemplary of the principles of the invention and not intended to limit the invention to the embodiments illustrated. The scope of the invention will be measured by the appended claims and their equivalents.
• Referring toFIGS. 1-3, a priorart syringe assembly20 includes abarrel21 having anelongate body22 defining achamber23 for retaining fluid. The barrel includes an openproximal end25, an opendistal end26 including acollar27 having aninternal thread28 therein. The barrel also includes anannular sealing surface29.
• A priorart needle assembly30 includes acannula31 having aproximal end32, anddistal end33 and a lumen (not shown) therethrough. Ahub35 includes abody portion36 having aproximal end37 and adistal end38, a passageway therethough. The body portion further includes an external thread for mating engagement with the thread in the barrel collar and anannular sealing surface40 positioned for contacting sealingsurface29 of the barrel.
• Ahollow needle shield41 includes an openproximal end43 and adistal end44. The open proximal end of the needle shield frictionally engages the body portion of the needle hub. The needle shield is provided to protect the cannula during handling and attaching the needle assembly to a syringe barrel at which time it is removed so that the needle and syringe can be used for their intended purpose.
• Attaching the needle assembly to the barrel involves placing the proximal end of the needle hub body in the barrel collar and rotating the needle assembly so that the thread on the needle assembly engages the thread in the barrel collar. Continued rotation closes the hub to enter the collar in a distal direction and continue moving in that direction until theannular sealing surface40 on the hub contacts annular sealingsurface29 in the barrel. Additional rotation will render the interface of the two annular sealing surfaces fluid tight.
• The most common prior art needle hub and syringe connection (not shown) involves a frusto-conically shaped tip on the syringe barrel which engages a frusto-conically shaped recess in the hub. During installation the rotational forces required increase as the frusto-conically shaped tip frictionally engages the corresponding recess in the hub. In the embodiment illustrated, the transition from relatively unrestricted rotation to sealing is more abrupt. If the user does not provide enough additional torque after the sealing surfaces have contacted, the syringe and needle assembly may leak fluid during the injection process. Excessive force can damage the fitting or over-stress the fitting so that it may be compromised over time. A good analogy to the present situation is the commonly available machine screw and threaded nut assembly. Without a torque wrench to facilitate the installation, it is left up to the common sense and experience of the user. In the minority of cases, some users do not tighten the screw and nut enough and it subsequently becomes loose or, in the alternative, the user over tightens the combination until the threads are stripped and the connection becomes inoperable.
• The present invention overcomes this problem by providing a syringe and needle assembly that limits the amount of torque that can be applied when attaching a needle assembly to a barrel and provides feedback to the user indicating that proper installation has occurred. Thus providing a uniform sealed connection between the needle assembly and the barrel over a wide range of users both weak and strong and experienced and inexperienced.
• Referring toFIGS. 4-7, a syringe andremovable needle assembly47 having binary attachment features includes anelongate syringe barrel48 having alongitudinal axis49, aninside surface50 defining achamber51 for retaining fluid, an openproximal end52, an opendistal end53 including acollar55. A portion of the collar includes a cylindrically shaped sidewall56 having aninside surface57 and anoutside surface58.
• Needle assembly61 includes ahub62 having abody portion63 including aproximal end64, adistal end65 and a conduit therethrough. The needle assembly further includes acannula70 having adistal end71, aproximal end72 and alumen73 therethrough. The proximal end of the cannula is connected to the distal end of the hub so that the lumen of the cannula is in fluid communication with the chamber in the barrel. The cannula may be integrally formed with the hub as by injection molding using thermoplastic materials or separately formed, as in this embodiment, and attached to the hub. In this embodiment, adhesive74 is used to attach the cannula to the hub, and the cannula is made of metal, preferably stainless steel.
• The present invention contains structural and functional features that to avoid the use of excessive torque when attaching the needle assembly to the syringe barrel and feedback features so the user knows when the needle assembly is properly attached to the barrel. In particular, the present invention includes at least one lug on the collar or on the hub and a ramp and a rest surface on the other of the collar or the hub. When attaching a needle assembly to a syringe barrel the lug moves along the ramp until it reaches the rest surface which prevents the needle assembly from being secured more tightly than it is at this point.
• In this preferred embodiment,body portion63 ofhub62 includes an outwardly projecting lug and insidesurface57 ofcollar55 includes aramp59 positioned at an acute angle with respect to the longitudinal axis of the barrel. The ramp terminates in arest surface60 which is preferably, but not necessarily, in a plane perpendicular to the longitudinal axis of the barrel.Collar55 includes an aperture75 therethrough. The rest surface includes a portion of the periphery of the aperture. Formation of this aperture will be discussed in more detail herein after.
• When attaching the needle assembly to the barrel, the user positions the proximal end of the hub inside the collar and rotates the hub with respect to the barrel so thatlug68 travels alongramp59. The hub moves into the collar sealing the hub and the barrel against leakage, at which time, the lug transitions from the ramp to the rest surface. At this point, the user experiences a reduction in the amount of torque necessary to rotate the hub with respect to the barrel which is a sign that the needle assembly is properly attached to the barrel. In this preferred embodiment, the structure provided for sealing the hub to the barrel includes a distally facing annular surface76 projecting inwardly into the open proximal end of the syringe barrel. A proximally facing annular surface69 onbody portion63 of the hub is positioned for contacting distally facing annular surface76 of the barrel to form a seal between the hub and barrel and prevent leakage during the injection process. It should be noted that proximally facing annular surface69 on the hub and distally facing annular surface76 in the barrel need not be aligned exactly at 90° from the longitudinal axis. A broad range of angles will work with the angles of 88° to 92° being desired, and 90° being preferred.
• The rotation of the hub with respect to the barrel during the attachment process, while the lug travels along the ramp results in a rotation of the needle assembly of less than 180° with respect to the barrel and preferably less than 100°. When the lug transitions onto the rest surface, further rotation of the hub with respect to the barrel will not result in a substantial additional tightening of the seal between the hub and the barrel.
• Another important feature of the present invention is that the hub is loosely retained by the barrel during most of the travel by the lug along the ramp so that the syringe and needle assembly are incapable of injecting fluids without leaking fluid outside the lumen until the lug is positioned on the rest surface. This retention during the movement of the lug along the ramp may be so slight that the needle assembly could easily become disengaged from the barrel further alerting the user to the fact that the needle assembly is not properly attached. Syringe assemblies having threaded connections between the needle hub and the barrel do not have this feature.
• The syringe assembly may also include anelongate plunger rod81 having aproximal end82, adistal end83 and astopper84 at the distal end of the plunger rod. The stopper is slidably positioned in fluid tight engagement withinside surface50 of the barrel for dispensing fluid from the chamber through the cannula by relative motion of the plunger rod with respect to the barrel. The stopper desirably includes adistally facing projection85 for partially occluding the distal end of the barrel when the stopper is in its distal most position inside the barrel to reduce dead space.
• As best illustrated inFIG. 7, the collar includes aguide surface86 running along and spaced fromramp59 for guiding the lug during removal of the needle assembly from the barrel. This feature is not necessary to practice the present invention but is preferred since the guide surface also helps align the lugs during attachment of the needle assembly to the syringe barrel.
• It is also within the purview of the present invention to include a discontinuity between the ramp and the rest surface for providing additional tactile feedback to the user during rotation of the needle assembly with respect to the barrel as the lug transitions from the ramp to the rest surface. Such a discontinuity is illustrated aselement87 inFIG. 8 as the lug travels upramp59 to restsurface60, its path is interrupted bydiscontinuity87 which, in this configuration, increases the amount of torque necessary to rotate the needle hub with respect to the barrel until the lug travels over the discontinuity and falls ontorest surface60. The discontinuity can take many configurations. Here discontinuity87 lengthens the travel of the lug to the rest surface, however, this is not necessary and any form of detent which is detectable by the user through touch and/or audible feedback is within the purview of the present invention anddiscontinuity87 is merely representative of these many possibilities.
• FIGS. 9 and 10 illustrate another structure for providing tactile feedback to the user during rotation of aneedle assembly161 with respect to abarrel148 as alug168 transitions from aramp159 to arest surface160. In this embodiment, aprojection188 onhub162 engages aprotuberance189 on collar155 of the syringe barrel at the approximate angular position where the lug is transitioning fromramp159 to restsurface160. This feature provides tactile feedback to the user that the needle assembly is properly attached to the barrel and no further twisting action is required. This feature also provides resistance to accidental or unintentional removal of the needle assembly. Also, the structure in this embodiment does not modify the ramp and rest surface configuration so that each function can be optimized without affecting the other. There are many combinations of projections and protuberances on the hub and barrel for accomplishing this result and the outwardlyprojection188 and the recessedprotuberance189 illustrated inFIGS. 10 and 11 are merely representative of these many possibilities, all of which are within the purview of the present invention.
• FIGS. 11 and 12 illustrate another alternative embodiment of the present invention. Thisembodiment hub262 includes abody portion263 having a plurality oflugs268 extending outwardly therefrom.Syringe barrel248 includes acollar255 having aninside surface256.Body portion263 of the hub further includes an outwardly projectingannular sealing ring290 which in this embodiment is an elastomeric o-ring. When the needle assembly is attached to the syringe barrel, outwardly projectingannular sealing ring290 engages insidesurface256 of the collar to form a seal between the hub and the barrel to help prevent leakage of the contents of the barrel through the space between the hub and the barrel.
• FIG. 13 illustrates aneedle assembly261 having an alternative outwardly projectingsealing ring291 on a hub that is similar to the hub ofFIG. 11. In this embodiment, outwardly projectingannular sealing ring291 is integrally formed with the body portion of the hub for sealing engagement with the inside surface of the collar to form a seal between the hub and the barrel. In this embodiment,annular sealing ring291 is a tapered projection having a base292 adjacent tobody portion263 of the hub and a free-end293. The tapered projection is preferably wider at its base than at its free-end. A wide variety of materials and structures can be used to form an annular sealing ring and the structures illustrated inFIGS. 12-14 are merely representative of these many possibilities, all of which are in the purview of the present invention.Needle assembly261 further includes acannula270 having adistal end271, aproximal end272 and alumen273 therethrough.Hub body portion263 andcannula270 are integrally formed of thermoplastic material.Cannula270 further includes a bluntdistal tip274 rather than a sharp distal tip as illustrated in the embodiment ofFIGS. 4-7.
• FIGS. 14 and 15 illustrate another alternative embodiment of the present invention. In thisembodiment syringe barrel348 includes an opendistal end353 having acollar355 wherein a portion of the collar includes a cylindrically shapedsidewall356 having anoutside surface358. A needle assembly includes ahub362 having abody portion363 including aconduit367 therethrough, anannular collar366 preferably having fourlugs368 on its interior surface. Outsidesurface358 ofcollar355 preferably includes tworamps359 and arest surface360 associated with each ramp. Additional rest surfaces366 may be provided without ramps. The ramp is oriented at an acute angle with respect tolongitudinal axis349 of the barrel, for guidinglugs368 during needle assembly attachment, to rest surfaces360.Hub362 includes proximally facingannular sealing surface369 including an annular proximally facing skirt308. The annular proximally facing skirt contacts a distally facing annular sealing surface in the barrel when the needle assembly is properly installed. The inclusion of an annular proximally facing skirt provides a more flexible surface on the hub for improving the quality of seal between the hub and the distally facing annular surface of the barrel.
• A syringe and needle assembly of this embodiment functions similarly to the previous embodiments in that the lug travels along the ramp during installation of the needle assembly to the barrel which is complete when the lug rests onrest surface360. Also included in this embodiment, is a discontinuity for providing additional resistance to the movement of the lug as it transitions from the ramp to the rest surface. Also this discontinuity is intended to provide additional resistance to the lugs when the needle assembly is being removed from the syringe barrel. In this embodiment it is preferred that the rotation of the hub with respect to the barrel be less than 100° while the lug travels along the ramp during installation of the needle assembly to the barrel. Further, the lug and the ramp structure are configured so that the hub is loosely retained by the barrel during most of the travel of the lug along the ramps so that the syringe and needle assembly are incapable of injecting fluid without leaking fluid outside of the lumen before the lug reaches the rest area.
• FIGS. 16 and 17 illustrate still another embodiment of the present invention. This embodiment includes anelongate syringe barrel448 having alongitudinal axis449, aninside surface450 defining achamber451 for retaining fluid, an opendistal end453 including acollar455. A portion of the collar includes a cylindrically shapedsidewall456 having aninside surface457. Four lugs468 are positioned equally distant alonginside surface457 and project inwardly. Aneedle assembly461 includes ahub462 having abody portion463. Two outwardly projectingramps459 and four outwardly projecting rest surfaces460 are equally spaced around the periphery of the body portion of the hub. In this embodiment, two of the lugs will move up two ramps during installation of the needle assembly and rest on the rest surfaces. The other two lugs will rest onrest surfaces460 that do not have ramps. The syringe barrel includes a distally facingannular surface476 projecting inwardly into the open proximal end of the barrel. The hub includes a proximally facingannular surface469 for contacting the distally facing annular surface to form a seal between the hub and the barrel. This embodiment functions similarly to the embodiment ofFIGS. 4-7.
• FIGS. 18 and 19 illustrate still another embodiment of the present invention. In this embodiment, anelongate syringe barrel548 includes alongitudinal axis549, an inside surface defining a chamber for retaining fluid, an open proximal end, and opendistal end553 including acollar555. A portion of the collar includes a cylindrically shapedsidewall556 having anoutside surface558. Four equally spacedlugs568 are positioned onoutside surface558 of the collar. A needle assembly includes ahub562 having abody portion563.Body portion563 includes anannular skirt566 having an inside surface. At least two ramps are positioned on the inside surface and project inwardly. Each ramp terminates in a rest surface is preferably perpendicular to thelongitudinal axis549. This embodiment functions similarly to the embodiment ofFIGS. 4-7. The needle assembly is attached to the syringe barrel through rotation of the hub which engages the lugs causing them to move along the ramps and onto the rest surfaces wherein the needle assembly is sealed to the barrel.
• Referring toFIGS. 20 and 21, syringe barrels, such asbarrel21, are frequently made by injection molding. The process involves the use of a mold cavity and associated core pins that define an empty space in the shape of a syringe barrel. Molten plastic is injected into the space and solidifies through cooling to form the barrel. Thread cores, likethread core24, are used to create threads in syringe barrels. The core is the negative of the internals of the desired part geometry. Once the part is molded, the thread core must be removed without smearing ordamaging threads28. This is achieved by unscrewing the thread core. This unscrewing action is driven by various gears, racks, hydraulics and/or motors depending on the mold design. This complexity adds cost to manufacture the mold. Also since the unscrewing action cannot be conducted concurrently with other mold actions such as opening and closing the mold press. Accordingly, the time to unwind the core adds to the process cycle time increasing the cost to manufacture the parts. Since barrel molds are usually of a multi-cavity configuration with many molds containing over 100 cavities, unwinding thread cores adds another degree of complexity of the tool design which increases the mold costs, cycle time and tool maintenance requirements.
• An important aspect of the present invention is a method of making syringe barrels without using an unwinding threaded core. In accordance with the provisions of the present invention,FIGS. 22 and 23 illustrate a process for molding a syringe barrel, such assyringe barrel48 of FIGS.4,5 and7, described in detail hereinabove. In this embodiment, aninjection mold700 comprises a fixedbody portion701 defining outside surface ofbarrel48, aproximal core pin702 definingchamber51 in the barrel andmovable split cavity703 defining anoutside surface58 ofcollar55. The movable split cavity also include a raisedprojection704 for forming an aperture incollar55 and portions oframp59 andrest surface60. Adistal core pin705 contacts the raised projection on thesplit cavity703 when the mold is closed and defines the remaining portions of the interior of the collar. Thus, the fixed portion, the proximal core pin, the movable split cavity and the distal core pin define acavity707 in the shape of the syringe barrel.
• The method of the present invention further includes injecting molten thermoplastic material intocavity707 of the mold; allowing enough time for thermoplastic material to solidify enough to allow movement of the barrel with respect to the mold cavity; opening the split cavity so that the raised projection on the split cavity is outside of the collar and removing the proximal core pin and the molded barrel axially from the fixed portion of the mold without rotating the distal core pin,
• It should be noted that the movable split cavity may also include asecond projection708. The distal core pin is configured to cooperate with the second projection to form a second aperture in the collar and anadditional rest surface366 spaced betweenramps359 and rest surfaces360 as illustrated on the syringe ofFIG. 14.
• Also, the raised projection on the split cavity can be further configured to cooperate with the distal core pin to form aguide surface86 in the collar, running along and spaced from the ramp, for guiding the lug during removal of the needle assembly from the barrel.
• A wide variety of thermoplastic materials are suitable for the formation of the syringe barrel using the method of the present invention. Preferably the thermoplastic material is selected from the group consisting of polypropylene, polyethylene, polycarbonate, PET and combinations thereof.
• The method of making a syringe barrel of the present invention allows thread-like structures (ramps) to be created without using a threaded core and without producing undercuts. This is achieved by a moving split cavity and a stationery straight pull distal core pin. The distal core pin creates the minor diameter of the ramps, while the major diameter is created by the movable split cavity. This method of creating the ramps results in the simpler tool design that can be done with fewer components than with unwinding methods. Fewer moving parts will require less maintenance. In addition, the action required to open the split cavity is done concurrently with the mold opening movement.

Claims (35)

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 ofclaim 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 ofclaim 2 wherein said proximally facing annular surface on said body portion of said hub is a flexible skirt.

4. The syringe assembly ofclaim 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 ofclaim 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 ofclaim 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 ofclaim 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 ofclaim 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 ofclaim 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 ofclaim 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 ofclaim 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 ofclaim 11 wherein said rest surface includes a portion of the periphery an aperture through said sidewall.

13. The syringe assembly ofclaim 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 ofclaim 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 ofclaim 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 ofclaim 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 ofclaim 16 wherein said annular sealing ring is an elastomeric o-ring.

18. The syringe assembly ofclaim 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 ofclaim 16 wherein said annular sealing ring is integrally formed with said body portion.

20. The syringe assembly ofclaim 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 ofclaim 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 ofclaim 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 ofclaim 1 wherein said hub and said cannula are integrally formed of thermoplastic material.

24. The syringe assembly ofclaim 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 ofclaim 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 ofclaim 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 ofclaim 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 ofclaim 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 ofclaim 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 ofclaim 32 wherein said thermoplastic material is selected from the group consisting of polypropylene, polyethylene, polycarbonate, PET and combinations thereof.

34. The method ofclaim 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 ofclaim 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.

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