CA 02314647 2000-07-27
SAFETY SYRINGE WITH A NEEDLE SLEEVE
BACKGROUND OF THE INVENTION
In the medical practices of early days, a used syringe
would be thoroughly sterilized for repeated use later.
Any incomplete sterilization would dangerously cause a
second time infection of a patient and/or any other people.
To avoid such second time infection, disposable syringes
are largely produced. However, large amount of discarded
disposable syringes also bring us new problems of
environmental pollution and safety of syringes in use.
This is because no specific measures have been taken in
disposing cannulas of the discarded syringes and exposed
cannulas tend to easily stab nursing or cleaning personnel
and result in even more infected people. Therefore, many
safety syringes are particularly developed. US Patent
Nos. 5, 562, 627; 5, 405, 327; 5, 569, 203; 5, 899, 887;
5, 395, 346, etc. all disclose safety syringes having
specially associated hubs and barrels, as well as
retractable barrels, so that hubs and cannulas of used
syringes can be pulled back into the barrels without the
risk of unexpectedly stabbing other people.
However, all these safety syringes of prior art developed
to improve conventional syringes have a common issue, that
is, the hubs of these safety syringes must be able to be
stably connected to the barrels and be pulled back into
the latter after the syringes have been used, and the hubs
must be connected to the barrels in an absolutely airtight
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manner that requires very high techniques to meet this
requirement. As it is known that, when such safety
syringes are assembled in the manufacturing process
thereof, the hubs and the barrels must first be associated
with one another before the syringes are sterilized, so
that the assembled syringes would not be contaminated
after the sterilization due to contact of any part of the
syringes. However, the assembled hubs and barrels are
subject to stress deformation and thermal deformation
during the sterilization under high temperature and such
deformation would have adverse influence on the stable
and airtight connection of the hubs to the barrels.
It is therefore tried by the inventar to develop a further
improved safety syringe to eliminate the drawbacks
existing in the safety syringes of prior art.
SUN~IARY OF THE INVENTION
A primary object of the present invention is to provide
a safety syringe with a needle sleeve that is particularly
made to improve a conventional safety syringe with a
retractable hub. The needle sleeve of the safety syringe
of the present invention allows the syringe to be
sterilized with the hub and the barrel thereof in a
contacted but non-engaged state, so that no stress and
thermal deformations of the syringe would occur to
adversely affect the stable and airtight connection of
the hub to the barrel of the syringe after the
sterilization.
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.:
Another object of the present invention is to provide a
safety syringe with a needle sleeve, so that the needle
sleeve firmly holds the cap, the hub and the barrel of
the syringe together, allowing the cannula and the hub
to be isolated from external environment and protected
against contamination due to any external contacting of
the cannula before the syringe is used to inject. The
needle sleeve also allows easy retaining of the hub to
the barrel of the safety syringe simply by depressing the
cap.
A further object of the present invention is to provide
a safety syringe with a needle sleeve. The needle sleeve
is provided at an inner wall with two stoppers against
which a rear end of the cap abut, preventing the cap from
being undesirably depressed to cause undesired early
engagement of the hub with the barrel before the syringe
is to be used for injection.
BRIEF DESCRIPTION OF THE DRAWINGS
The structure and the technical means adapted by the
present invention to achieve the above and other objects
can be best understood by referring to the following
detailed description of the preferred embodiments and the
accompanying drawings, wherein
Fig. 1 is an exploded perspective of a safety syringe with
a needle sleeve according to a first embodiment of the
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present invention, and Fig. lA is a vertical sectional
view of the needle sleeve shown in Fig. 1;
Fig. 2 is an exploded perspective of a safety syringe with
a needle sleeve according to a second embodiment of the
present invention
Fig. 3 is a vertical sectional view of the needle sleeve
shown in Fig. 2, and Fig. 3A is a cross sectional view
of the needle sleeve of Fig. 3 taken on line A-A;
Fig. 4 is a sectional view of a hub and a cap of the safety
syringe of the present invention in an assembled state;
Fig. 5 is an enlarged and fragmentary sectional view of
the first embodiment of the safety syringe of the present
invention, showing the manner of assembling the hub, the
cap, and the needle sleeve, wherein the hub has not been
retained to a neck portion of a barrel of the safety
syringe:
Fig. 5A is an enlarged and fragmentary sectional view of
the second embodiment of the safety syringe of the present
invention, showing the manner of assembling the hub, the
cap, and the needle sleeve, wherein the hub has not been
retained to a neck portion of a barrel of the safety
syrmge~
Fig. 6 is a sectional view similar to Fig. 5 but with the
hub being retained to the neck portion of the barrel of
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..
the safety syringe of Fig. 1;
Fig. 6A is a sectional view similar to Fig. 5A but with
the hub being retained to the neck portion of the barrel
of the safety syringe of Fig. 2;
Fig. 7 illustrates the manner of removing the cap and the
needle sleeve from the hub and the barrel of the safety
syringe of Fig. 1;
Fig. 7A illustrates the manner of removing the cap and
the needle sleeve from the hub and the barrel of the safety
syringe of Fig. 2;
Fig. 8 shows the engagement of a plunger of the safety
syringe of the present invention with the hub when the
plunger has been fully pushed forward in the barrel;
Fig. 9 shows the hub and the cannula of the safety syringe
of the present invention are pulled backward by the
plunger into the barrel when the cannula has been used;
and
Fig. 10 shows a needle sleeve and a cap for a safety syringe
according to a third embodiment of the present invention.
DETAILED DESCRIPTTON OF THE PREFERRED EMBODIMENTS
The present invention relates to-a retractable safety
syringe, components of which mainly include a barrel A,
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a plunger B slidably mounted in the barrel A, a hub C
connected to a front end of the barrel A for holding a
cannula C1 thereto, and a cap D for covering the cannula
C1. Any structure of these components that is similar
to that of a conventional safety syringe would not be
repeated herein. The safety syringe of the present
invention is characterized in a needle sleeve and
structures of other components of the syringe cooperating
with the needle sleeve. The needle sleeve is put around
joints of the hub C and the barrel A and of the hub C and
the cap D, as can be best seen in Figs. 5 and 5A.
Please refer to Fig. 1 that is an exploded perspective
of a safety syringe with a needle sleeve 1 according to
a first embodiment of the present invention. As can be
seen from Fig. 1A, the needle sleeve 1 is a hollow tube
defining an inner space therein. A front part of the inner
space of the needle sleeve 1 has a reduced inner diameter.
And, an inner peripheral wall 12 of this front part is
properly tapered toward a front end of the safety syringe,
that is, an end with the cannula C1. A rear part of the
inner space of the needle sleeve 1 has an expanded inner
diameter relative to the front part, and an inner
peripheral wall 13 of the rear part is properly tapered
toward the front end of the safety syringe, too. A first
shoulder portion 11 is therefore formed between the inner
peripheral wall 12 and the inner peripheral wall 13.
Please refer back to Fig. I. The hub C is formed near
a middle portion thereof with a second shoulder portion
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.. .
C2, and at a rear portion thereof with two diametrically
opposite engaging holes C3. The barrel A has a
diameter-reduced neck portion A2 that defines a front open
end of the barrel A. An inner peripheral wall A1 of the
front open end of the neck portion A2 inclines radially
inward. And, a third shoulder portion A3 is formed
between the inclined peripheral wall A1 and a straight
inner peripheral wall of the neck portion A2 behind the
inner open end of the neck portion A2.
In assembling the safety syringe of this first embodiment,
first extend the hub C and the cannula C1 connected thereto
into the cap D. The cap D is so designed that it has an
inner diameter similar to an outer diameter of a portion
of the hub C above the second shoulder portion C2, so that
the hub C could be tightly fitted in the cap D to form
a needle assembly as shown in Fig. 4. Thereafter, the
needle sleeve 1 is put around the needle assembly from
a front end of the cap D, so that the first shoulder portion
11 inside the needle sleeve 1 abuts on a rear flange D2
of the cap D. At this point, a rear end portion of a
forward tapered outer peripheral wall surface D1 and the
rear flange D2 of the cap D fitly contact with the front
and the rear inner peripheral walls 12, 13 of the needle
sleeve 1, respectively, with the first shoulder portion
11 abutted against the flange D2. The needle assembly
and the needle sleeve 1 put therearound therefore form
a needle sleeve assembly. As can be clearly seen from
Fig. 5, the hub C is completely covered by the needle sleeve
1 and isolated from external environment and accordingly,
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any contamination possibly caused by undesirably
contacting the cannula C1. The needle sleeve assembly
is then assembled to the barrel A by engaging the inner
peripheral wall 13 of the rear part of the needle sleeve
1 with an outer peripheral wall of the reduced neck portion
A2 of the barrel A, as shown in Fig. 5, to form a syringe
assembly, that is, the safety syringe according to the
first embodiment of the present invention. Before being
used to inject a medical liquid, this syringe assembly
has a hub C that has a rear bottom portion contacting with
the inclined inner peripheral wall A1 at the front open
end of the neck portion A2 of the barrel A without being
extended into and retained to the neck portion A2. The
syringe assembly is then sterilized under high
temperature in this state.
Since the hub C is not fully extended into and retained
to the neck portion A2 of the barrel A when the syringe
assembly is sterilized under high temperature, there
would not be any stress produced at this sterilization
stage. Therefore, any stress deformation and any thermal
deformation of the whole syringe due to such high
temperature sterilization could be avoided.
To use the syringe assembly for injection of any medical
liquid, a user may depress a front end of the cap D, so
that the hub C tightly fitted in the cap D is brought to
move downward at the same time . When the second shoulder
portion C2 on the hub C is downward moved to pass through
the radially inward inclined peripheral wall surface A1
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and the third shoulder portion A3 at the front open end
of the neck portion A2 of the barrel A, the hub C would
not be able to be pulled forward again to separate from
the barrel A. At this point, an outer peripheral wall
surface of the rear portion of the hub C behind the second
shoulder portion C2 would contact with the straight inner
peripheral wall surface of the neck portion A2 behind the
third shoulder portion A3 in a tight fit manner, as shown
in Fig. 6, so that an airtight effect at the joint of the
hub C and the barrel A is accomplished. Finally, the cap
D is pulled forward to expose the cannula C1. When doing
so, the rear flange D2 of the cap D would be moved to abut
against the first shoulder portion 11 inside the needle
sleeve 1 and therefore brings the needle sleeve 1 to
separate from the hub C at the same time, as shown in Fig.
7. After the cap D and the needle sleeve 1 have been
removed to expose the cannula C1, the safety syringe
according to the first embodiment of the present invention
is ready for use.
When using the safety syringe according to the first
embodiment of the present invention to inject a patient
with medical liquid, the plunger B is fully pushed forward
in the barrel A until an engaging cone B2 provided at a
front end of the plunger B engages with the engaging holes
C3 provided at the rear portion of the hub C, as shown
in Fig. 8. After the injection, the plunger B may be
pulled backward to bring the hub C, which is now associated
with the plunger B, and the cannula C1, that is connected
to the hub C, to move back into the barrel A, as shown
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in Fig. 9.
Please now refer to Fig. 2 that is an exploded perspective
of a retractable safety syringe with a needle sleeve 1'
according to a second embodiment of the present invention.
The needle sleeve 2' is similar to the needle sleeve 1
except it is provided with means to prevent the cap D from
being undesirably depressed. Figs . 3 and 3A show vertical
and cross sections, respectively, of the needle sleeve
1'. All parts on the needle sleeve 1' similar to that
of the needle sleeve 1 are denoted with the same reference
numerals. The means on the needle sleeve 1' to prevent
the cap D from being undesirably depressed are two
diametrically opposite square through holes 14 formed on
the rear part of the needle sleeve 1' immediately behind
the first shoulder portion 11. Two areas on the inner
peripheral wall 13 separately immediately adjacent to
rear edges of the hales 14 radially proj ect inward to form
two first stoppers 15. The safety syringe of this second
embodiment has a cap D' similar to the cap D of the first
embodiment but having two second stoppers D2' provided
at the rear end thereof to replace the rear flange D2.
The barrel A, the plunger B, the hub C, and the cannula
C1 of the safety syringe of the second embodiment, and
the assembling of these components are similar to those
in the first embodiment, as shown in Figs. 4, 5A, 6A, 7A,
8 and 9.
The needle sleeve 1' is put around the needle assembly
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,.
from a front end of the cap D' , so that the second stoppers
D2' are located behind the first shoulder portion 11
inside the needle sleeve 1' and before the first stoppers
15, preventing the cap D' from moving rearward relative
to the needle sleeve 1'.
Fig. 10 shows a needle sleeve 1" and a cap D' far a
retractable safety syringe according to a third
embodiment of the present invention. The needle sleeves
1" is structurally similar to the needle sleeve 1' except
it includes two third stoppers 15' that separately axially
extend from one end of the first stoppers 15 toward a front
end of the needle sleeve 1". The second stoppers D2' on
the cap D' would finally abut against the two third
stoppers 15' when the cap D' is turned to locate the second
stoppers D2' between the first shoulder portion 11 and
the first stoppers 15. The third stoppers 15' prevent
the cap D' from being overly turned.
As a matter of fact, the fitted contact of the forward
tapered outer peripheral wall surface D1' of the cap D'
with the front inner peripheral wall 12 of the needle
sleeve 1' itself enables the cap D' and the needle sleeve
1' to stably connect to each other without the risk of
becoming turnable relative to each other, unless there
is an external force applied to turn them. Thus, the cap
D' and the needle sleeve 1' could still be stably connected
without the third stoppers 15'.
To enhance the stable connection of the needle sleeve 1'
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to the cap D', it is also possible to provide the first
stoppers 15 and the second stoppers D2' with inclined
contact surfaces between. them, so that a tightness of
contact of the cap D' with the needle sleeve 1' increases
with a degree of turning of the cap D' relative to the
needle sleeve 1'.
In both of the above two embodiments, the caps D' is turned
counterclockwise to separate the second stoppers D2' from
the first stoppers 15. And then, the caps D' may be
depressed to firmly assemble the hub C to the barrel A
for injection.
With the above-described arrangements, the safety syringe
of the present invention is sterilized under high
temperature before the hub C is tightly fitted into the
front neck portion A2 of the barrel A. Therefore, any
stress and thermal deformations at the joint of the hub
and the barrel of the syringe possibly caused by such high
temperature sterilization may be avoided. The safety
syringe can therefare always maintain good airtightness
at such joint. Moreover, the needle sleeve 1 protects
the hub C and the barrel A of the safety syringe against
any contamination due to undesirable contact of the hub
before use. In the second and the third embodiments, the
stoppers 25 and D2' serve as safety to further prevent
the cap from being undesirably depressed.
The safety syringe.with a needle sleeve of the present
invention is therefore superior to the conventional
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