Safety syringe abstract
A safety syringe has a barrel, a needle hub movably received in
the barrel and having a hollow cone formed inside the needle hub
and an annular cutout, a stopper having an engaging portion formed
to correspond to the annular cutout and an extension integrally
formed with the engaging portion and being slanted relative to the
engaging portion, and a plunger having a first hook to correspond
to the hollow cone and a second hook to correspond to the extension
of the stopper. Engagement between the second hook and the extension
of the stopper allows the stopper to be taken away from engagement
with the needle hub and engagement between the first hook and the
hollow cone allows the needle hub to be pulled inside the barrel
and thus the syringe is able 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, a stopper detachably engaged with the needle hub
and a plunger slidably received in the barrel and having a head
extending out to engage with the stopper, wherein the improvements
comprise: the barrel is hollow inside to receive therein the needle
hub, the stopper and the plunger and has a step formed on an inner
periphery thereof, the needle hub is movably received in the barrel
and has a tubular connector formed inside a body for connection
with a needle, a hollow cone formed inside the tubular connector
and an annular cutout defined in a bridge which is formed to connect
the tubular connector to the body, the stopper has an engaging portion
formed to correspond to the annular cutout and an extension integrally
formed with the engaging portion and being slanted relative to the
engaging portion, the plunger has a thumb push formed on an end
relative to the head of the plunger, a first hook adapted to be
formed on a front portion of the head to correspond to the hollow
cone and a second hook adapted to be formed on a rear portion of
the head to correspond to the extension of the stopper, whereby
after injection rearward movement of the plunger first allows engagement
between the second hook and the extension of the stopper so that
the stopper is taken away from engagement with the needle hub and
then engagement between the first hook and the hollow cone so that
the needle hub is pulled inside the barrel and thus the syringe
is able to be disposed of safely.
2. The safety syringe as claimed in claim 1 wherein the engaging
portion has a dimension larger than a dimension of the annular cutout
so that when the engaging portion is received in the corresponding
annular cutout, a dimension of the needle hub is partially enlarged
so as to ensure engagement between an outer periphery of the needle
hub and an inner periphery of the barrel is fluid-tight.
3. The safety syringe as claimed in claim 1 wherein the hollow
barrel further has multiple stops formed on a distal end of the
hollow barrel to correspond to multiple secondary stops formed on
an inner face of the needle hub so that after the needle hub is
received in the hollow barrel, the stops and the secondary stops
are aligned with one another and relative position between the hollow
barrel and the needle hub is secured.
4. The safety syringe as claimed in claim 2 wherein the hollow
barrel further has multiple stops formed on a distal end of the
hollow barrel to correspond to multiple secondary stops formed on
an inner face of the needle hub so that after the needle hub is
received in the hollow barrel, the stops and the secondary stops
are aligned with one another and relative position between the hollow
barrel and the needle hub is secured.
Safety syringe description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a safety syringe, and more particularly
to a labor efficient safety syringe. The syringe has a barrel, a
plunger movably received in the barrel and provided with an extension,
a first hook formed on a front portion of the extension and a second
hook formed on a rear portion of the extension, a needle hub movably
received in the barrel to engage with the first hook and a stopper
movably received in the barrel to engage with the second hook. Engagement
between the needle hub and the first hook and the engagement between
the stopper and the second hook enable the needle together with
the needle hub to be readily retracted into the barrel so that accidental
damage to the paramedic is prevented.
2. Description of Related Art
A conventional syringe is shown in FIG. 7 and has a barrel (5),
a needle hub (6) and a plunger (7).
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).
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).
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).
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.
To overcome the shortcomings, the present invention tends to provide
an improved labor efficient safety syringe to mitigate and obviate
the aforementioned problems.
SUMMARY OF THE INVENTION
The primary objective of the present invention is to provide an
improved labor efficient safety syringe so that the user is able
to readily pull the needle hub back into the barrel.
In order to accomplish the foregoing objective, the syringe has
a barrel, a plunger movably received in the barrel and provided
with an extension, a first hook formed on a front portion of the
extension and a second hook formed on a rear portion of the extension,
a needle hub movably received in the barrel to engage with the first
hook and a stopper movably received in the barrel to engage with
the second hook. Engagement between the needle hub and the first
hook and the engagement between the stopper and the second hook
enable the needle together with the needle hub to be readily retracted
into the barrel so that accidental damage to the paramedic is prevented.
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
FIG. 1 is an exploded plan view showing the parts of the syringe
of the present invention;
FIG. 2 is a cross sectional view showing an assembly among the
barrel, the needle hub and the stopper;
FIG. 3 is a cross sectional view showing the assembly in FIG. 2
together with the plunger to be inserted through the needle hub;
FIG. 4 is a cross sectional view showing the assembly in FIG. 2
together with the plunger inserted through the needle hub;
FIG. 5 is a schematic view showing the engagement of the plunger
and the needle hub as well as the stopper;
FIG. 6 is a schematic view showing that the entire needle hub together
with the needle is pulled back into the barrel; and
FIG. 7 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
With reference to FIG. 1 the safety syringe in accordance with
the present invention has a barrel (1), a needle hub (2), a stopper
(3) and plunger (4).
The barrel (1) is hollow inside to receive therein the needle hub
(2), the stopper (3) and the plunger (4). The barrel (10) further
has multiple stops (12) formed on a distal end thereof to secure
relative position between the barrel (1) and a needle hub (2), which
will be described in detail in the following description.
The needle hub (2) is movably received in the barrel (1) and has
a tubular connector (21) formed inside a body (20) for connection
with a needle (not shown), a hollow cone (22) formed inside the
tubular connector (21) and an annular cutout (23) defined in a bridge
(24) which is formed to connect the tubular connector (21) to the
body (20). The needle hub (2) further has multiple secondary stops
(26) formed to correspond to the stops (12) of the barrel (1) so
that when the needle hub (2) is inserted into the barrel (1), each
of the stops (12) is aligned with a corresponding one of the secondary
stops (26) so that the relative position between the barrel (1)
and the needle hub (2) is secured, wherein the secondary stops (26)
may be recesses and the stops (12) may be bosses.
The stopper (3) has an engaging portion (31) and an extension (32)
integrally formed with the engaging portion (31) and being slanted
relative to the engaging portion (31). The engaging portion (31)
has a dimension larger than a dimension of the annular cutout (23).
The plunger (4) has a thumb push (41) formed on a first end of
the plunger (4) and a head (42) formed on a second end of the plunger
(4) and having a first hook (421) formed on a front portion of the
head (42) to correspond to the hollow cone (22) and a second hook
(422) formed on a rear portion of the head (42) to correspond to
the extension (32) of the stopper (3).
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 tubular connector (21) extended out of
the hollow barrel (1) for engaging with a needle. Because of a flange
(25) formed on an outer periphery of the barrel (2) and a step (11)
formed on an inner periphery of the barrel (1), after the needle
hub (2) is inserted into the barrel (1), the needle hub (2) is positioned
inside the barrel (1). Then, the engaging portion (31) of the stopper
(3) is force fitted into the annular cutout (23) of the needle hub
(2) to enlarge the dimension of the annular cutout (23), which ensures
that engagement between the inner periphery of the barrel (1) and
an outer periphery of the needle hub (2) is water tight.
Because the extension (32) is inclined so that after the stopper
(3) is inserted into the barrel (1) and the engaging portion (31)
is received in the annular cutout (23), the extension (32) extends
toward an inside of the hollow cone (22).
With reference to FIGS. 3 and 4 after the foregoing assembly,
the syringe of the present invention is ready for use. Therefore,
when the user is using the syringe to perform a hypodermic injection,
the user extends the plunger (4) into the barrel (1). After the
extension of the plunger (4) into the barrel (1), because the user
needs to inject the medicine inside the barrel (1) to the recipient
(the patient), the first hook (421) extends through the hollow cone
(22). Thereafter, the second hook (422) extends over the extension
(32) to completely expel the medicine out of the barrel (1). Basically,
the foregoing description is the same as the conventional injection
process. However, after the medicine is completely expelled out
of the barrel (1), the first hook (421) leaves engagement with the
hollow cone (22) and the second hook (422) engages with the extension
(32) of the stopper (3).
With reference to FIG. 5 after injection, in order to have the
syringe of the present invention disposed of safely, the user pulls
the plunger (4) inward into the barrel (1), which triggers engagement
between the second hook (422) of the plunger (4) and the extension
(32) of the stopper (3). Because the engagement between the second
hook (422) and the extension (32) overcomes the friction engagement
between the engaging portion (31) and the annular cutout (23), the
stopper (3) is pulled away from engagement with the needle hub (2).
After the disengagement, the user continues pulling backward the
plunger (4) into the barrel (1) and eventually the first hook (421)
of the plunger (4) engages with the hollow cone (22). Because the
stopper (3) is already detached from the needle hub (2), the originally
enlarged portion of the needle hub (2) recovers to its original
dimension so that the rearward movement of the plunger (4) is able
to readily pull the needle hub (2) into the barrel (1), as shown
in FIG. 6.
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. |