U.S. patent application number 10/952975 was filed with the patent office on 2005-03-10 for hub assembly for a retractable needle syringe and method of making.
Invention is credited to Targell, John.
Application Number | 20050054980 10/952975 |
Document ID | / |
Family ID | 27256157 |
Filed Date | 2005-03-10 |
United States Patent
Application |
20050054980 |
Kind Code |
A1 |
Targell, John |
March 10, 2005 |
Hub assembly for a retractable needle syringe and method of
making
Abstract
A fluid handling device comprises a barrel for containing fluid
to be delivered through a needle, a needle-mounting hub at one end
of the barrel, a biasing element arranged to urge the hub inwardly
of the barrel, a stop element blocking inward movement of the hub
into the barrel, and a hollow plunger which is movable within the
barrel to deliver fluid from the barrel via the needle and has at
its forward end a portion which is severable in response to
movement of the plunger over the final part of, or at the
conclusion of, its delivery stroke to allow retraction of the
needle-mounting hub into the hollow plunger, the hub and the stop
element being formed as plastics mouldings in such a way that the
stop element is axially captive with the hub and the plunger being
arranged to disengage the stop element and the hub during said
final part of, or at the conclusion of, the delivery stroke to
allow the biasing element to drive the needle into the hollow
plunger.
Inventors: |
Targell, John; (Ayrshire,
GB) |
Correspondence
Address: |
BAKER & DANIELS
111 E. WAYNE STREET
SUITE 800
FORT WAYNE
IN
46802
|
Family ID: |
27256157 |
Appl. No.: |
10/952975 |
Filed: |
September 29, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10952975 |
Sep 29, 2004 |
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10133104 |
Apr 26, 2002 |
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6800066 |
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60290733 |
May 14, 2001 |
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Current U.S.
Class: |
604/110 |
Current CPC
Class: |
A61M 5/508 20130101;
A61M 5/3234 20130101 |
Class at
Publication: |
604/110 |
International
Class: |
A61M 005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 26, 2001 |
GB |
GB 0110194.8 |
Claims
1-26. (canceled)
27. A hub assembly for a retractable needle syringe, said hub
assembly comprising: a hub, said hub including a bore for
accommodating a mounting portion of a syringe needle, said hub made
of a first moldable plastic material; a crown made of a second
moldable plastic material, said crown surrounding said hub and
defining a substantial axial interface with said hub, said hub and
crown separably, sealingly, intimately, and form fittingly engaging
one another along said axial interface, whereby said hub and crown
can disengage from one another along said interface to define an
aperture in said crown when said crown and hub are subjected to a
separating force.
28. The hub assembly of claim 27 wherein said hub is held captive
in said crown.
29. The hub assembly of claim 27 wherein said hub assembly
comprises a two-shot molding.
30. The hub assembly of claim 27 wherein said crown includes a lip
seal.
31. The hub assembly of claim 27 wherein said lip seal is an
annular lip seal.
32. The hub assembly of claim 27 wherein said hub is elongated.
33. The hub assembly of claim 27 wherein said crown and hub each
include a formation, said formations inter-engaging one another
along said interface.
34. The hub assembly of claim 27 wherein said hub and crown adhere
to one another along said interface.
35. The hub assembly of claim 27 wherein said hub and crown are
fusingly bonded to one another along said interface.
36. The hub assembly of claim 27 wherein said first and second
plastic material are substantially similar.
37. The hub assembly of claim 27 wherein said hub and crown each
include an annular surface, said annular surfaces are complementary
with one another and defining said interface.
38. The hub assembly of claim 37 wherein said annular surfaces are
substantially cylindrical.
39. The hub assembly of claim 33 wherein said formations define
detents.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation application of U.S.
patent application Ser. No. 10/133,104 filed Apr. 26, 2002,
entitled "RETRACTABLE NEEDLE SYRINGE," now U.S. Patent No. 6,0,066
granted Oct. 5, 2004.
[0002] This invention relates to fluid handling devices, such as
medical syringes, in which a plunger is used to deliver fluid from
a barrel of the device via a needle.
[0003] For safety reasons, e.g. to avoid needle stick injuries, it
is desirable that the needle is retracted into the barrel following
delivery of the fluid. Our prior U.S. Pat. No. 5,782,804 discloses
a fluid handling device provided with a needle retraction mechanism
of this type.
[0004] The present invention seeks to provide a fluid handling
device having a simplified needle retraction mechanism.
[0005] According to the present invention there is provided a fluid
handling device comprising a barrel for containing fluid to be
delivered through a needle, a needlemounting hub at one end of the
barrel, a biasing element arranged to urge the hub inwardly of the
barrel, a stop element blocking inward movement of the hub into the
barrel, a hollow plunger which is movable within the barrel to
deliver fluid from the barrel via the needle and has at its forward
end a portion which is severable in response to movement of the
plunger over the final part of, or at the conclusion of, its
delivery stroke to allow retraction of the needle-mounting hub into
the hollow plunger, the hub and the stop element being formed as
plastics mouldings in such a way that the stop element is axially
captive with the hub and the plunger being arranged to disengage
the stop element and the hub during said final part of, or at the
conclusion of, the delivery stroke to allow the biasing element to
drive the needle into the hollow plunger.
[0006] The stop element may incorporate an integral seal, e.g. a
lip seal, which may be annular so as to encircle the stop
element.
[0007] The stop element and the hub may have interengaged
formations at the location of the moulding interface which are
caused to separate from one another during said final part of, or
at the conclusion of, the delivery stroke of the plunger.
[0008] The stop element and the hub may alternatively or
additionally be at least partially united. e.g. partially fused,
together at the moulding interface, the arrangement being such that
the connection is fractured or broken during said final part of, or
at the conclusion of, the delivery stroke.
[0009] The hub may be elongate and may have a central bore for
reception of the needle.
[0010] The needle-receiving bore may be of reducing
cross-section.
[0011] The hub may be produced with some degree of draft, i.e. so
as to be of reducing cross section in a direction of travel of the
plunger during its delivery stroke.
[0012] The biasing element may be a helical spring, usually a
compression spring, which may be arranged in encircling relation
with the hub. One end of the spring may coact with a forward end of
the barrel or an end cap attached to the main body of the barrel
and the opposite end of the spring may coact with the hub at a
location inwardly of the forward end of the barrel.
[0013] The forward end of the plunger may comprise a rim portion
and a central blocking portion, the latter forming said severable
portion.
[0014] The arrangement may be such that, during the final part of
or at the conclusion of the plunger delivery stroke, the rim
portion of the plunger is arranged to engage the stop element while
the hub is arranged to engage the blocking portion, the engagement
between the two sets of components being effective to free the hub
from the stop element and to free the blocking portion from the rim
portion at least to the extent necessary to allow the hub to enter
the interior of the plunger.
[0015] Preferably the hub is freed from the stop element before the
blocking portion is at least partially freed from the rim portion;
however, if desired the blocking portion may be freed first or
alternatively the hub and the blocking portion may be freed
substantially simultaneously.
[0016] The arrangement may be such that the hub and stop element
are united together by the moulding process to afford a
well-defined threshold at which they break away from one another in
response to the application of force to the stop element in the
course of operating the plunger.
[0017] Preferably one of the components (hub and stop element) is
produced as a plastics moulding in a mould having moulding surfaces
defined, in part, by the other component, i.e. moulding of one
component being effected with the other component in situ.
[0018] The two portions may be of plastics materials having
different chemical compositions and/or characteristics or they may
both be of substantially the same or a similar plastics
material.
[0019] The hub and stop element may be capable of being broken away
from each other without deformation of either of the two portions
and, to this end, the moulding interface may be shaped so that no
deformation of either component occurs when breaking one from the
other.
[0020] Alternatively, the hub and the stop element may be
interlocked with each other so that some deformation of at least
one of the parts occurs when effecting the break.
[0021] At the moulding interface, an annular surface of one of the
components may be have a configuration complementary with an
annular surface of the other component.
[0022] The annular surfaces may be cylindrical or of other
configuration, e.g. conical.
[0023] At the moulding interface, the components may intimately
contact each other with a degree of fusion bonding consistent with
securing fracture preferentially at the interface region during the
break.
[0024] The assembly of the hub and stop element may include a
detent arrangement acting between the components. The detent
arrangement may be provided at or in the vicinity of said moulding
interface. For example, the hub and the stop element may, by virtue
of the mould design, have interengaging formations which lock the
components together to prevent separation, and at least one of the
formations may be resiliently deformable to allow the disengagement
of the formations on application of sufficient loading to the stop
element relative to the hub.
[0025] Resistance to separation of the two components may
additionally or alternatively be afforded by the nature of the
interaction between material or materials of the hub and the stop
element at the moulding interface. For instance, there may a shrink
type fit between the components at the moulding interface obtained
by material shrinkage during cooling following the moulding
process.
[0026] As a further addition or alternative to the detent
arrangement and/or shrink type fit mentioned above, resistance to
separation may be provided by fusion bonding between the components
at the moulding interface. Such fusion bonding may range from
relatively weak, e.g. as a result of some degree of diffusion of
material from one component across the moulding interface into the
other component, through to relatively strong.
[0027] Depending on the nature of interaction desired between the
hub and the stop element at the moulding interface, the material or
materials from which said portions are produced may be selected so
as to secure the desired extent of fusion bonding, if any. For
example, if negligible fusion bonding is desired, the materials
employed will usually differ in chemical and/or physical
characteristics and will be such that no significant diffusion of
material takes place across the moulding interface as a result of
the moulding process. Similarly the materials can be appropriately
selected to obtain the desired degree of fusion bonding where there
is a requirement to develop a fusion bond at the moulding
interface.
[0028] In the latter case for example, the hub and the stop element
may be composed of the same material so that significant fusion of
the material takes place between the two components.
[0029] The width of the moulding interface and hence the zone of
contact between the two components may be selected with regard to
the required effectiveness of the seal and/or with regard to the
resistance to separation of the components required at said
interface. For instance, a given degree of resistance may be
secured by a relatively narrow interface where the components are
strongly fusion bonded together whereas a wider interface may be
required if resistance is afforded by shrinkage and/or a weak
fusion bond.
[0030] Irrespective of how the hub and the stop element are coupled
together, the arrangement may be such that the resistance to
separation of the two parts is greater with respect to forces
applied in one direction compared with forces applied in the
opposite direction.
[0031] Where one part is moulded in advance of the other and the
second part is then moulded with the first part in situ, the first
part to be moulded may have a higher heat distortion temperature
than the second part so that the first part is not deformed during
moulding of the second part.
[0032] The stop element and the hub may advantageously be formed in
a two-shot moulding process in which one component, e.g. the hub,
is initially formed and located so that an annular surface thereof
forms a boundary surface of the mould cavity in which the other
component is produced so that, during formation of the second
component, an annular surface of the latter is conformed with the
annular surface of the first component.
[0033] The manner of coupling together the hub and the stop element
as referred to in the preceding paragraphs may also be employed to
couple together the rim portion and the blocking portion, e.g. as
disclosed in our U.S. patent application Ser. No. 10/149,342, the
entire disclosure of which is incorporated herein by this
reference.
[0034] Other aspects of the invention include a needle-mounting hub
assembly produced as a two-shot moulding and comprising a hub and a
stop element captive with the hub, and a method of manufacturing
such an assembly.
[0035] The invention will now be described by way of example with
reference to the accompanying drawings in which:
[0036] FIG. 1 is a side view of a syringe which may embody features
of the present invention;
[0037] FIG. 2 is a fragmentary sectional view of the syringe
showing the plunger approaching the final part of its delivery
stroke;
[0038] FIG. 3 is a similar view to that of FIG. 2 but with the
plunger shown at its point of initial contact with the crown
associated with the needlemounting hub;
[0039] FIG. 4 is similar view to that of FIG. 2 at the conclusion
of the plunger delivery stroke and showing the needle undergoing
retraction into the hollow plunger; and
[0040] FIG. 5 is detail view of the needle-mounting hub and
crown.
[0041] Referring now to the drawings, the disposable medical
syringe 10 comprises a hollow barrel 12, from the rear of which
(upper end as viewed in FIG. 1) protrudes a plunger 14. A seal 15
is mounted on the plunger to ensure a fluid tight seal with the
internal wall of the barrel. The barrel 12 includes an end cap 12A
including a cylindrical section 16 which is engaged with a annular
collar 18 of the main body of the barrel 12 and a generally conical
section 20. The end cap 12A may be permanently bonded to the main
body of the barrel 12 or it may be releasably attached thereto. A
needle-mounting hub 22 is accommodated within the end cap 12A and
is encircled by a spring 24 which engages at its forward end with a
flange 26 of the conical section 20 and at its rear end with a
radial shoulder 28 on the hub 22 and serves to bias the hub 22 and
needle 30 inwardly relative to the barrel 12.
[0042] The hub 22 is of generally cylindrical configuration and has
an axial bore 32 for reception of the needle 30. The bore 32 may be
a throughbore as illustrated. The bore 32 is of tapering
configuration to allow the needle to be fitted to the hub as a
press-fit or by spin-welding either before or after the end cap 12A
has been assembled to the main body of the barrel.
[0043] Rearward movement of the hub and needle assembly is
prevented by a stop element in the form of a crown 34 which is
carried by hub 22 and is received within the annular collar 18. The
crown 34 is of generally cylindrical configuration and comprises a
forward portion 36 incorporating an integral annular lip seal 38
and a reduced diameter portion 40. As shown in FIG. 5, prior to
insertion into the annular collar 18, the lip seal flares outwardly
as shown in FIG. 5 and is resiliently flexible so that, on
insertion into the collar, it is deflected radially inwardly so as
to bear against and make sealing engagement with the inner surface
of the collar 18. At its forward end, the collar 18 includes a
lead-in portion 42 to facilitate insertion of the crown 34.
[0044] The hub and crown are produced as plastics mouldings by
two-shot moulding which serves to integrate the two components and
render them captive with each other so that they effectively
constitute a one-piece component designed to fracture at the
interface between the hub and the crown when subjected to a
predetermined forwardly directed axial force. In addition, the
assembly of hub and crown incorporates the lip seal 38 which may be
integral with the crown since the latter can be moulded from
polyethylene for example. In this way, needle mounting and sealing
at the forward end of the barrel is considerably simplified
compared for example with the arrangement disclosed in our prior
U.S. Pat. No. 5,782,804. At the interface between the hub and
crown, the components may have interfitting formations, e.g. mating
frusto-conical surfaces, which may determine at least in part the
force needed to separate the two components.
[0045] The plunger 14 is hollow and has a closed trailing end. The
forward end of the plunger is arranged to receive a closure
assembly comprising an insert 52 which engages firmly in the
plunger to form an end wall of the plunger while defining an
aperture 54 which is sufficiently large to allow the needle 30 and
hub 22 to pass through during needle retraction.
[0046] The insert 52 comprises a rim portion 55 fitted with a
forwardly projecting blocking portion 56 of generally
frusto-conical configuration so that the blocking portion 56 closes
and seals the aperture 54. The blocking portion 56 and rim portion
55 seal the forward end of the plunger to prevent ingress of liquid
into the plunger interior from the interior of barrel 12.
[0047] The rim and blocking portions 55, 56 are also formed as
plastics mouldings by two-shot moulding so that the two portions 55
and 56 are integrated and captive with each other. A closure
assembly of this form is disclosed in U.S. patent application Ser.
No. 10/149,342 (the entire contents of which are incorporated
herein by this reference) and the design of these components may be
as described and illustrated therein. The rim and blocking portions
55, 56 are coupled together in such a way that they can be
separated from each other in response to the application of a
predetermined axial force as described in U.S. patent application
Ser. No. 10/149,342.
[0048] Although the hub 22 and crown 34 may have interengaging
formations 80, 82 at the interface between them such that these
formations render the respective components captive to one another
and contribute to the resistance to separation of the components,
such interengaging formations 80, 82 are not essential as long as
sufficient resistance to separation at the interface is available,
e.g. as described below. Whether or not such formations are
provided, it will be appreciated that the "forceto-break" or allow
the components to separate from each other can be tailored
according to requirements by appropriate design of features such as
the angle of the interface between the two parts and/or the surface
texture present at the interface and/or extent of the
interface.
[0049] In accordance with a preferred feature of the invention,
each assembly comprising parts 22, 34 and 55, 56 respectively is
produced by a two-shot moulding process, for instance a first stage
in which the inner part 22, 56 is produced followed by a second
stage in which the outer part 34, 55 is moulded onto the inner part
22, 56 thereby connecting the two parts together, e.g. through the
interengaging formations 80, 82 (if present) and/or through a zone
of intimate contact which sealingly engages the two parts with each
other at the moulding interface. Two-shot moulding technology may
be carried out for instance using a multi-stack moulding machine
such as available from Milacron Inc of Cincinnati, Ohio, USA in
which a two-sided pivoting centre platen allows two simultaneous
moulding operations to be carried out. The process starts with a
preform injected into cavities on one mould face. The mold opens,
the centre platen swivels through 180 degrees in a vertical plane,
locks into position, the mold closes, and a second material
component is injected. At the same time, another pre-form is
injected into the opposite mould face of the centre platen. In this
way, a preform and a completed part are injection-moulded
simultaneously during each cycle of operation using two plastic
melts which may be the same material, similar or different
materials. A two-shot moulding machine is also disclosed in U.S.
Pat. No. 6,139,305.
[0050] To prevent the inner and outer parts 22, 34 and 55,56
welding together inseparably during the moulding process, the two
parts may be moulded using materials which are compatible with each
other and have different characteristics. However, some degree of
fusion bonding between the rim and closure parts may be desirable,
e.g. to ensure sealing and, where desired, to play a role in
predetermining the loading necessary to break the blocking portion
away from the rim portion.
[0051] The closure assembly in FIGS. 2 to 4 is shown fitted into
the forward end of the plunger 6; however, in an alternative
embodiment, the rim portion may be formed integrally with at least
the forward end portion of the plunger so that the plunger and rim
portion can be produced as a single moulding. For example, both the
plunger and rim portion may be made from a plastics material such
as polyethylene or polypropylene. In this case, the other end of
the plunger may be closed by an end cap.
[0052] The parts 22, 34 and 55, 56 may be held captive to one
another by interengaging formations 80, 82 (as illustrated for
parts 22, 34) which may act as a detent-type arrangement. However,
instead of or in addition to such a detent-type arrangement, the
parts may be rendered captive to one another as a result of some
degree of fusion or bonding of the materials at the interface
and/or by virtue of an interference or shrink type fit between the
parts at a zone of contact, e.g. as illustrated in FIG. 3 of U.S.
patent application Ser. No. 10/149,342. The shrink fit may be
obtained during the moulding process by moulding the outer part 34,
55 around the inner part 22, 56 and exploiting material shrinkage
on cooling to secure the interference fit. Where the inner part is
held captive in this way, there is not necessarily any significant
fusion bonding between the materials although, if desired, the
material(s) may be selected so that such fusion bonding is present,
e.g. as a result of some degree of diffusion of material between
the two parts.
[0053] When the hub and crown are assembled as shown in FIG. 2, the
rearward end of the lip seal 38 engages a shoulder 44 while the
reduced diameter portion 40 of the crown projects beyond an annular
end wall 46 of the main body of the barrel 12 for cooperation with
the forward end of the plunger 14 as described below. Likewise, the
blocking portion 56 is arranged for entry into the opening defined
by the crown 34 to contact the rearward end of the hub 22.
[0054] In operation, as the plunger 14 is displaced inwardly into
the barrel 12, the contents of the barrel are delivered through the
needle. As the plunger approaches completion of its stroke, the
condition shown in FIG. 3 is reached in which the rim portion 55 is
in contact with, or about to contact, the rearward end of the crown
34 while the blocking portion 56 is in contact with, or about to
contact, the rearward end of the hub 22. By appropriate design of
the components, the axial force developed by continued displacement
of the plunger to the completion of its stroke (see FIG. 4) results
in the connections between the parts 22, 34 and 55, 56 being
broken, e.g. fractured, freeing the hub 22 from the crown 34 and
freeing of the blocking portion 56 from the rim portion 55.
[0055] More specifically, the rim portion 55 displaces the crown 34
forwardly while engagement between the hub, which is blocked from
forward movement by the forward end of the portion 12A, and the
blocking portion 56 exerts a rearwardly directed force on the
latter. Under these conditions, once the connections rendering
parts 22, 34 and 55, 56 captive with one another are broken, the
spring 24 is no longer restrained and becomes effective to propel
the hub through the crown, through the aperture created by freeing
of the blocking portion 56 and into the interior of the plunger
thereby concealing the needle and avoiding the risk of needle stick
injury once the contents of the syringe have been delivered.
Freeing of the hub and the blocking portion may occur substantially
simultaneously or in sequence, freeing of the hub first being
currently preferred. The forces required to effect freeing of the
hub and the blocking portion may be readily tailored to
requirements by for example appropriate selection of the
dimensioning/configuration of the components, tuning of the
two-shot moulding process etc.
[0056] In the course of being displaced by the rim portion 55, the
extent of travel of the crown 34 is such that the lip seal 38
remains in sealing contact with the internal surface of the collar
18. Although the hub may be of generally cylindrical configuration,
it is desirable to produce it with a draft (i.e. of reducing
cross-section from its trailing end towards its forward end) so as
to facilitate easy ejection and prevent binding of the spring
against the peripheral surface of the hub. The hub may be
manufactured so that, when assembled as shown in FIG. 2, there is a
small clearance between the shoulder 28 and the adjacent end wall
of the end cap 12A thereby eliminating any risk of the hub/crown
hub connection being broken during assembly of the syringe (i.e.
because of tolerance variations in the length of the hub). This
clearance is taken up as when the rim portion of the plunger
initially contacts and begins to displace the crown.
[0057] From the foregoing, it will be seen that the present
invention as embodied in the illustrated syringe results in a much
simplified design compared with that of U.S. Pat. No. 5,782,804.
Advantages that can be realized include the following:
[0058] better control of the release force needed to separate the
hub from the crown since the two-shot moulding can be tuned to
requirements;
[0059] the possibility of increasing the diameter of the spring to
allow a shorter, more robust design;
[0060] an integral lip seal rather than an "0" ring seal which
reduces the risk of premature firing and low pressure failures;
[0061] a shorter travel of the crown with reduced risk of
accidental firing when expelling air;
[0062] reduced tolerance dependency;
[0063] greater control of the timing/sequencing of the needle
retraction process;
[0064] simplified assembly since the hub/crown/lip seal effectively
comprises a single component;
[0065] redesign of the end cap 12A to enable easier moulding;
[0066] possibility of needle insertion into the hub after the
latter has been installed, thereby reducing the risk of needle
damage;
[0067] hub design permits press-fit or spin-weld needle
fixation;
[0068] ullage can be reduced and be more consistent; and
[0069] higher locking force (inserting needle into vials etc) as
the hub and crown are moulded in one piece.
[0070] While endeavoring in the foregoing specification to draw
attention to those features of the invention believed to be of
particular importance, it should be understood that the Applicant
claims protection in respect of any patentable feature or
combination of features disclosed herein and/or shown in the
drawings whether or not particular emphasis has been placed on such
feature or features.
* * * * *