Safety syringe abstract
A safety syringe has a barrel, a needle hub movably received in
the barrel and having a hollow cone with a flange formed on an inner
periphery of the hollow cone and a plunger with a hook formed to
correspond to the flange of the needle hub such that when the hook
engages with the flange of the needle hub, the needle hub is ready
to be pulled back into the barrel by a rearward movement of the
plunger so that the syringe is ready to be disposed of safely.
Safety syringe claims
What is claimed is:
1. In a safety syringe having a barrel, a needle hub movably received
in the barrel and having a needle securely attached to a distal
end of the needle hub and a plunger slidably received in the barrel
and having a thumb press formed on a first distal end of the plunger
and a stop formed on a second distal end of the plunger, wherein
the improvements comprise: the needle hub has a hollow cone with
a flange formed on an inner periphery of the hollow cone; and the
plunger has a hook adapted to be integrally formed on a top face
of the stop to correspond to the flange of the needle hub so that
when the hook engages with the flange of the needle hub, the needle
hub is able to be pulled back into the barrel by a rearward movement
of the plunger and the needle is damaged by a forward movement of
the plunger after the needle hub is entirely received in the barrel.
Safety syringe description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a retracting device for
a safety syringe, and more particularly to a retracting device which
is able to satisfactorily pull the needle hub back into the barrel
so that the syringe is able to be safely disposed.
[0003] 2. Description of Related Art
[0004] A conventional syringe is shown in FIG. 6 and has a barrel
(5), a needle hub (6) and a plunger (7).
[0005] The barrel (5) has a step (51) formed on an inner face thereof.
The needle hub (6) has a flange (61) corresponding to the step (51)
and having a diameter slightly larger than a diameter of the step
(51). The plunger (7) has a stopper (71) and a hook (72) formed
on a distal end of the plunger (7). The needle hub (6) further defines
an annular cutout (62) to receive therein an engaging portion (711)
of the stopper (71) and a retaining portion (63) formed to maintain
the stopper (71) to be in engagement with the needle hub (6). The
stopper (71) has an extension (712) extending out of the annular
cutout (62) to correspond to the hook (72).
[0006] When the needle hub (6) is received in the barrel (5), because
the diameter of the flange (61) is larger than the step (51), the
diameter of the step (51) is enlarged so that the engagement between
the needle hub (6) and the barrel (5) is secured. Then, the engaging
portion (711) of the stopper (71) is received in the annular cutout
(62) of the needle hub (6).
[0007] When the plunger (7) is pushed in the barrel (5) toward
the needle hub (6), the hook (72) first passes over the extension
(712) of the stopper (71) so as to complete an injection. Thereafter,
when the user is pulling the needle hub (6) together with the needle
(not shown) back into the barrel (5) in order to safely dispose
of the syringe, the hook (72) engages with the extension (712) of
the stopper (71) and then the user is able to pull the needle hub
(6) together with the stopper (71) inward to the inside of the barrel
(5).
[0008] However, problems often happen to the users when trying
to dispose of the syringe of this type. That is, if the engagement
between the flange (61) and the step (51) is too tight, the user
will have difficulty pulling the needle hub (6) back into the barrel
(5) and if the engagement between the flange (61) and the step (51)
is too loose, the needle hub (6) will automatically fall into the
barrel (5) when the user is trying to have medicine received inside
the syringe. Accordingly, a precise calculation of the dimension
of the needle hub (6), the plunger (7) and even the barrel (5) should
be taken carefully so that a proper engagement among the needle
hub (6), the plunger (7) and the barrel (5) is available.
[0009] To overcome the shortcomings, the present invention tends
to provide an improved retracting device for a safety syringe to
mitigate and obviate the aforementioned problems.
SUMMARY OF THE INVENTION
[0010] The primary objective of the present invention is to provide
an improved retracting device for a safety syringe so that the user
is able to readily pull the needle hub back into the barrel.
[0011] In order to accomplish the foregoing objective, the syringe
has a barrel, a plunger movably received in the barrel and provided
with a hook integrally formed with a stop which is formed on a distal
end of the plunger, a needle hub movably received in the barrel
and having a flange formed on an inner periphery of the needle hub
to correspond to the hook. Engagement between the needle hub and
the hook enables the needle together with the needle hub to be readily
retracted into the barrel so that accidental damage to the paramedic
personnel is prevented.
[0012] Other objects, advantages and novel features of the invention
will become more apparent from the following detailed description
when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is an exploded perspective view showing the parts
of the syringe of the present invention;
[0014] FIG. 2 is a cross sectional view showing an assembly among
the barrel, the needle hub and the plunger;
[0015] FIG. 3 is a cross sectional view showing the hook engages
with the flange of the needle hub;
[0016] FIG. 4 is a cross sectional view showing that the needle
hub is retracted back into the barrel by the reward movement of
the plunger;
[0017] FIG. 5 is a schematic view showing that the needle of the
needle hub is broken by the forward movement of the plunger; and
[0018] FIG. 6 is a cross sectional view showing the assembly of
the barrel, the needle hub, the stopper and the plunger of a conventional
safety syringe.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0019] With reference to FIG. 1 the safety syringe in accordance
with the present invention has a barrel (1), a needle hub (2) and
a plunger (3).
[0020] The barrel (1) is hollow inside to receive therein the needle
hub (2) and the plunger (3).
[0021] The needle hub (2) has an annular boss (21) formed on an
outer periphery of the needle hub (2) and the barrel (1) has an
annular recess (11) defined to correspond to the annular boss (21)
such that when the needle hub (2) is received in the barrel (1),
as shown in FIG. 2 the annular boss (21) is received in the annular
recess (11), which allows the needle hub (2) be detachably received
in the barrel (1). The needle hub (2) has a hollow cone (22) and
a flange (23) formed on an inner periphery of the hollow cone (22)
of the needle hub (2).
[0022] The plunger (3) has a thumb push (31) formed on a first
distal end of the plunger (3) and a stop (32) formed on a second
distal end of the plunger (3) and having a hook (321) integrally
formed on a front portion of the stop (32) to correspond to the
hollow cone (22).
[0023] With reference to FIG. 2 when the safety syringe of the
present invention is in assembly, the needle hub (2) is first inserted
into the barrel (1) to have the annular boss (21) of the needle
hub (2) received in the annular recess (11) of the barrel (1) so
as to secure a relative position of the needle hub (2) to the barrel
(1). Meantime, the plunger (3) is also received in the barrel (1)
to be ready to receive medicine in the barrel (1). From FIG. 2 it
is noted that before the safety syringe of the present invention
is in use, a distance exists between the stop (32) and the hollow
cone (22) so that the hook (321) is not in engagement with the flange
(23) of the hollow cone (22).
[0024] Furthermore, the hook (321) is preferably made of a metal.
The hook (321) is bent so that a free end of the hook (321) is resilient
relative a distal end securely formed with the stop (32).
[0025] With reference to FIG. 3 when the medicine inside the barrel
(1) is ejected, the user pushes the plunger (3) all the way into
the barrel (1) to force the stop (32) to engage with the hollow
cone (22). When the stop (32) engages with the hollow cone (22),
the hook (321) is received in the hollow cone (22). Because of the
resilience of the hook (321), the hook (321) is able to engage with
the flange (23) of the hollow cone (22). Thereafter the user is
ready to pull the needle hub (2) back into the barrel (1).
[0026] With reference to FIG. 4 after the needle hub (2) is retracted
in the barrel (1), because the free end of the hook (321) is in
engagement with one point of the flange (23), the needle hub (2)
is inclined relative to the barrel (1). When the needle hub (2)
is inclined to and fully received in the barrel (1), a forward movement
of the plunger (3) together with the needle hub (2), as shown in
FIG. 5 results in the needle (24) being bent inside the barrel
(1) such that the safety syringe of the present invention is able
to be disposed of safely.
[0027] It is thus noted that the retracting device used in the
safety syringe of the present invention includes the hook (321)
formed with the stop (32) and a flange (23) formed on the inner
periphery of the hollow cone (22) of the needle hub (2).
[0028] It is to be understood, however, that even though numerous
characteristics and advantages of the present invention have been
set forth in the foregoing description, together with details of
the structure and function of the invention, the disclosure is illustrative
only, and changes may be made in detail, especially in matters of
shape, size, and arrangement of parts within the principles of the
invention to the full extent indicated by the broad general meaning
of the terms in which the appended claims are expressed. |