Abstrict A disposable syringe includes an encasing member which is sleevable
on a syringe body from a needle hub of the syringe body. A needle
cannula is secured to the needle hub and projects outwardly of a
surrounding front segment of the encasing member in a position of
use. A plunger is slidably disposed in a barrel wall of the syringe
body in a longitudinal direction. The syringe body is movable relative
to the encasing member in the longitudinal direction between the
position of use, where the needle hub is disposed in the surrounding
front segment, and a disposal position, where the needle cannula
is disposed inwardly of the surrounding front segment as a result
of withdrawal of the needle hub from the surrounding front segment.
Claims We claim:
1. A disposable syringe comprising: a syringe body including a
surrounding barrel wall which has an axis, front and rear surrounding
ends opposite to each other in a longitudinal direction parallel
to the axis, an outer surrounding wall surface, and an inner surrounding
wall surface opposite to said outer surrounding wall surface, said
inner surrounding wall surface confining an accommodation chamber,
a front end wall which extends from said front surrounding end radially
and towards the axis to confine an internal port in fluid communication
with said accommodation chamber, a needle cannula disposed to extend
in the longitudinal direction, and a needle hub disposed to secure
said needle cannula to said front end wall such that said needle
cannula is in fluid communication with said accommodation chamber
through said internal port in the longitudinal direction; a plunger
including a head portion disposed to be movable in said accommodation
chamber and in slidable contact with said inner surrounding wall
surface, and a stem portion extending from said head portion in
the longitudinal direction and outwardly of said rear surrounding
end so as to be manually operated; an encasing member which is configured
to be sleevable on said syringe body from said needle hub, and which
includes a surrounding front segment that surrounds said needle
hub, and that permits said needle cannula to extend outwardly thereof
and to be retractable relative thereto, and a surrounding rear segment
extending from said surrounding front segment in the longitudinal
direction, to be sleeved on said surrounding barrel wall, and having
an inner tubular wall surface, said inner tubular wall surface confronting
and being movable relative to said outer surrounding wall surface
between a position of use, where said front end wall is closer to
said surrounding front segment, and where said needle cannula extends
outwardly of said surrounding front segment, and a disposal position,
where said front end wall is remote from said surrounding front
segment, and where said needle cannula is disposed inwardly of said
surrounding front segment as a result of withdrawal of said needle
hub from said surrounding front segment; and a retaining member
disposed between said inner tubular wall surface and said outer
surrounding wall surface to arrest unforced movement of said surrounding
barrel wall in the position of use.
2. The disposable syringe of claim 1 wherein said retaining member
includes male and female screw thread segments which are disposed
on said inner tubular wall surface and said outer surrounding wall
surface respectively, and which are angularly engageable once said
encasing member is brought over said needle hub and is sleeved on
said syringe body so as to restrain said surrounding barrel wall
from displacing along said surrounding rear segment in the longitudinal
direction, thereby placing said surrounding barrel wall in the position
of use.
3. The disposable syringe of claim 2 wherein said male and female
screw thread segments are configured such that said surrounding
barrel wall is angularly movable in a clockwise direction relative
to said surrounding rear segment so as to displace said surrounding
barrel wall from the position of use to the disposal position.
4. The disposable syringe of claim 3 further comprising a surrounding
retaining groove which is formed in said outer surrounding wall
surface adjacent to said front end wall and which is opposite to
said female screw thread segment in the longitudinal direction so
as to engage said male screw thread segment when said surrounding
barrel wall is in the disposal position, thereby restraining said
surrounding barrel wall from displacing along said surrounding rear
segment.
5. The disposable syringe of claim 4 further comprising a guideway
which is disposed on said outer surrounding wall surface, and which
extends to interconnect said female screw thread segment and said
surrounding retaining groove so as to facilitate the displacement
of said surrounding barrel wall from the position of use to the
disposal position.
6. The disposable syringe of claim 1 wherein said needle hub is
integrally formed with said front end wall and extends from said
front end wall in the longitudinal direction.
7. The disposable syringe of claim 6 wherein said surrounding
front segment has an inner front wall surface with a diameter which
is smaller than that of said inner tubular wall surface so as to
form a surrounding shoulder portion therebetween, such that said
front end wall abuts against said surrounding shoulder portion in
the position of use.
8. The disposable syringe of claim 7 wherein said needle hub has
a plurality of ribs displaced angularly from one another about the
axis, each of said ribs extending radially and outwardly so as to
create an increased friction force at said inner front wall surface,
thereby establishing greater friction engagement between said surrounding
front segment and said needle hub when said surrounding front segment
is sleeved on said needle hub.
9. The disposable syringe of claim 1 wherein said surrounding
rear segment further has an outer tubular wall surface radially
opposite to said inner tubular wall surface, and a plurality of
slots disposed in said outer tubular wall surface and extending
through said inner tubular wall surface so as to expose a portion
of said surrounding barrel wall.
10. The disposable syringe of claim 1 wherein said surrounding
front segment has an outer front wall surface which has a rib portion
extending in the longitudinal direction, said disposable syringe
further comprising a tip protector which has a sleeve end disposed
to sleeve on said outer front wall surface, said sleeve end including
a groove portion which mates with said rib portion to result in
a splined engagement between said tip protector and said outer front
wall surface, thereby ensuring secure shielding of said needle cannula.
11. An intravenous catheter inserting device, comprising: a syringe
body including a surrounding barrel wall which has an axis, front
and rear surrounding ends opposite to each other in a longitudinal
direction parallel to the axis, an outer surrounding wall surface,
and an inner surrounding wall surface opposite to said outer surrounding
wall surface, said inner surrounding wall surface confining an accommodation
chamber, a front end wall which extends from said front surrounding
end radially and towards the axis to confine an internal port in
fluid communication with said accommodation chamber, a needle cannula
including a secured end and a cannula body which extends from said
secured end in the longitudinal direction, and a needle hub disposed
to secure said secured end of said needle cannula to said front
end wall such that said needle cannula is in fluid communication
with said accommodation chamber through said internal port in the
longitudinal direction; a plunger including a head portion disposed
to be movable in said accommodation chamber and in slidable contact
with said inner surrounding wall surface, and a stem portion extending
from said head portion in the longitudinal direction and outwardly
of said rear surrounding end so as to be manually operated; an encasing
member which is configured to be sleevable on said syringe body
from said needle hub, and which includes a surrounding front segment
that surrounds said needle hub, and that permits said needle cannula
to extend outwardly thereof and to be retractable relative thereto,
and a surrounding rear segment extending from said surrounding front
segment in the longitudinal direction, to be sleeved on said surrounding
barrel wall, and having an inner tubular wall surface, said inner
tubular wall surface confronting and being movable relative to said
outer surrounding wall surface between a position of use, where
said front end wall is closer to said surrounding front segment,
and where said needle cannula extends outwardly of said surrounding
front segment, and a disposal position, where said front end wall
is remote from said surrounding front segment, and where said needle
cannula is disposed inwardly of said surrounding front segment as
a result of withdrawal of said needle hub from said surrounding
front segment; a retaining member disposed between said inner tubular
wall surface and said outer surrounding wall surface to arrest unforced
movement of said surrounding barrel wall in the position of use;
a catheter hub including a surrounding hub wall which confines a
duct that extends along the axis, and which has a sleeve portion
that is sleeved on said surrounding front segment, and a tip portion
opposite to said sleeve portion along the axis; and a tubular catheter
including a proximate segment which is disposed in said tip portion
and which extends along the axis to communicate fluidly with said
duct, and a distal segment which extends from said proximate segment
along the axis to project outwardly of said tip portion, said cannula
body of said needle cannula extending along and in said tubular
catheter to terminate at a tip end that projects outwardly of said
distal segment of said tubular catheter.
12. The intravenous catheter inserting device of claim 11 wherein
said surrounding front segment has an outer front wall surface which
has a rib portion extending in the longitudinal direction, and a
front surrounding sleeved region disposed forwardly of said rib
portion such that said sleeve portion of said surrounding hub wall
is sleeved on said front surrounding sleeved region, said disposable
syringe further comprising a tip protector which has a sleeve end
disposed to sleeve on said outer front wall surface so as to shield
said needle cannula, said catheter hub and said tubular catheter.
Description BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a disposable syringe, more particularly
to a disposable syringe which enables a needle cannula to be retracted
within an encasing member.
[0003] 2. Description of the Related Art
[0004] Exposed needles of conventional disposable syringes may
prick the fingers of health care workers after use, and may infect
them with contagious fatal diseases, such as AIDS, hepatitis, etc.
To reduce the risk of accidents, a disposable syringe with a retractable
needle has been developed. However, such a disposable syringe suffers
from the following disadvantages in actual use:
[0005] 1. After injection, a plunger of the disposable syringe
has to be first pushed forwardly to couple with the needle and then
pulled rearwardly so as to pull the needle into the syringe body.
Thereafter, the plunger has to be broken at a certain point to prevent
inadvertent pressing of the plunger, which may cause the needle
to project from the syringe body once again. Such a retracting procedure
is relatively complicated, and considerations have to be given to
whether the plunger can be firmly coupled to the needle in order
to pull the needle that engages the front end of the syringe body.
The coupling of the plunger to the needle and the subsequent pulling
of the needle through the plunger are difficult to conduct since
the engagement between the needle and the syringe body poses a certain
resistance.
[0006] 2. In order to facilitate retraction of the needle, a greater
number of component parts are provided to couple the plunger to
the needle, which, however, increases costs and complicates assembly.
[0007] 3. Due to the provision of more component parts, the amount
of residual medication or blood trapped in dead corners of the disposable
syringe also increases to result in aggravated environmental pollution
problem.
SUMMARY OF THE INVENTION
[0008] The object of the present invention is to provide a disposable
syringe which has a relatively simple construction and which enables
retraction of a needle after use in a simple operating manner.
[0009] According to this invention, the disposable syringe includes
a syringe body, a plunger, an encasing member and a retaining member.
[0010] The syringe body includes a surrounding barrel wall which
has an axis, front and rear surrounding ends opposite to each other
in a longitudinal direction parallel to the axis, an outer surrounding
wall surface, and an inner surrounding wall surface opposite to
the outer surrounding wall surface. The inner surrounding wall surface
confines an accommodation chamber. A front end wall extends from
the front surrounding end radially and towards the axis to confine
an internal port that is in fluid communication with the accommodation
chamber. A needle cannula is disposed to extend in the longitudinal
direction. A needle hub is disposed to secure the needle cannula
to the front end wall such that the needle cannula is in fluid communication
with the accommodation chamber through the internal port in the
longitudinal direction.
[0011] The plunger includes a head portion which is disposed to
be movable in the accommodation chamber and which is in slidable
contact with the inner surrounding wall surface, and a stem portion
which extends from the head portion in the longitudinal direction
and outwardly of the rear surrounding end so as to be manually operated.
[0012] The encasing member is configured to be sleevable on the
syringe body from the needle hub, and includes surrounding front
and rear segments. The surrounding front segment surrounds the needle
hub, and permits the needle cannula to extend outwardly thereof
and to be retractable relative thereto. The surrounding rear segment
extends from the surrounding front segment in the longitudinal direction,
is to be sleeved on the surrounding barrel wall, and has an inner
tubular wall surface which confronts and which is movable relative
to the outer surrounding wall surface between a position of use,
where the front end wall is closer to the surrounding front segment,
and where the needle cannula extends outwardly of the surrounding
front segment, and a disposal position, where the front end wall
is remote from the surrounding front segment, and where the needle
cannula is disposed inwardly of the surrounding front segment as
a result of withdrawal of the needle hub from the surrounding front
segment.
[0013] The retaining member is disposed between the inner tubular
wall surface and the outer surrounding wall surface to arrest unforced
movement of the surrounding barrel wall in the position of use.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Other features and advantages of the present invention will
become apparent in the following detailed description of the preferred
embodiments of the invention, with reference to the accompanying
drawings, in which:
[0015] FIG. 1 is an exploded sectional view of the first preferred
embodiment of a disposable syringe according to this invention;
[0016] FIG. 2 is a schematic view of the first preferred embodiment;
[0017] FIG. 3 is a sectional view of the first preferred embodiment
in a state of use;
[0018] FIG. 4 is a sectional view of the first preferred embodiment
in a disposal state;
[0019] FIG. 5 is a schematic view of the second preferred embodiment
of a disposable syringe according to this invention;
[0020] FIG. 6 is a schematic view of the second preferred embodiment
in a disposal state;
[0021] FIG. 7 is a schematic view of the third preferred embodiment
of a disposable syringe according to this invention;
[0022] FIG. 8 is a sectional view of the fourth preferred embodiment
of a disposable syringe according to this invention; and
[0023] FIG. 9 is a sectional view of the fourth preferred embodiment
in a disposal state.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] Before the present invention is described in greater detail,
it should be noted that same reference numerals have been used to
denote like elements throughout the specification.
[0025] Referring to FIGS. 1 to 3 the first preferred embodiment
of a disposable syringe according to the present invention is shown
to comprise a syringe body 2 a plunger 3 an encasing member 1
a retaining member, and a tip protector 4.
[0026] The syringe body 2 includes a surrounding barrel wall 23
a front end wall 24 a needle cannula 26 and a needle hub 25. The
surrounding barrel wall 23 defines an axis (X), and has front and
rear surrounding ends 230 232 opposite to each other in a longitudinal
direction parallel to the axis (X). The surrounding barrel wall
23 has an outer surrounding wall surface 233 and an inner surrounding
wall surface 239 opposite to the outer surrounding wall surface
233. The inner surrounding wall surface 239 confines an accommodation
chamber 21. The front end wall 24 extends from the front surrounding
end 230 radially and towards the axis (X) to confine an internal
port 241 that is in fluid communication with the accommodation chamber
21. An annular retaining groove 234 is formed in the outer surrounding
wall surface 233 adjacent to the front end wall 24.
[0027] The needle hub 25 is integrally formed with the front end
wall 24 and extends from the front end wall 24 in the longitudinal
direction to terminate at an insert end 251. The needle cannula
26 includes a secured end 261 which is secured to the needle hub
25 from the insert end 251 and a cannula body which extends from
the secured end 261 in the longitudinal direction to terminate at
a tip end 262 that is disposed outwardly of the needle hub 25 such
that the needle cannula 26 is in fluid communication with the accommodation
chamber 21 through the internal port 241. The needle hub 25 further
has a plurality of ribs 252 which are displaced angularly from one
another about the axis (X), and each of which extends radially and
outwardly.
[0028] The plunger 3 includes a head portion 31 which is disposed
to be movable in the accommodation chamber 21 and which is in slidable
contact with the inner surrounding wall surface 239 and a stem
portion 32 which extends from the head portion 31 in the longitudinal
direction and outwardly of the rear surrounding end 232 of the surrounding
barrel wall 23 so as to be manually operated.
[0029] The encasing member 1 is sleevable on the syringe body 2
from the needle hub 25. The encasing member 1 includes a surrounding
front segment 13 and a surrounding rear segment 12 which extends
from the surrounding front segment 13 in the longitudinal direction.
The surrounding front and rear segments 13 12 have a smaller-diameter
inner front wall surface 131 and a larger-diameter inner tubular
wall surface 127 respectively, so as to form a surrounding shoulder
portion 14 therebetween. The surrounding front segment 13 surrounds
the needle hub 25 and has a front open end 132 to permit the needle
cannula 26 to extend outwardly thereof and to be retractable relative
thereto. The surrounding rear segment 12 is sleeved on the surrounding
barrel wall 23. Accordingly, the inner tubular wall surface 127
of the surrounding rear segment 12 confronts and is movable relative
to the outer surrounding wall surface 233 of the surrounding barrel
wall 23 between a position of use, as shown in FIG. 3 where the
front end wall 24 abuts against the surrounding shoulder portion
14 and where the tip end 262 of the needle cannula 26 extends outwardly
of the front open end 132 of the front surrounding segment 13 and
a disposal position, as shown in FIG. 4 where the front end wall
24 is remote from the surrounding front segment 13 and where the
tip end 262 of the needle cannula 26 is disposed inwardly of the
surrounding front segment 13 as a result of withdrawal of the needle
hub 25 from the surrounding front segment 13. Moreover, when the
surrounding front segment 13 is brought to be sleeved on the needle
hub 25 the ribs 252 of the needle hub 25 can create an increased
friction force at the inner front wall surface 131 thereby establishing
greater friction engagement between the needle hub 25 and the surrounding
front segment 13.
[0030] In addition, referring to FIGS. 1 and 2 an outer front
wall surface of the surrounding front segment 13 has a rib portion
133 which extends in the longitudinal direction. The tip protector
4 has a sleeve end 41 which is disposed to sleeve on the outer front
wall surface of the surrounding front segment 13. The sleeve end
41 includes a groove portion which mates with the rib portion 133
to result in a splined engagement between the tip protector 4 and
the outer front wall surface of the surrounding front segment 13
thereby ensuring secure shielding of the needle cannula 26.
[0031] The retaining member includes male and female screw thread
segments 128 235 which are disposed on the inner tubular wall surface
127 of the surrounding rear segment 12 and the outer surrounding
wall surface 233 of the surrounding barrel wall 23 respectively.
The male screw thread segment 128 includes a plurality of angularly
displaced ribs and surrounds the axis (X). The female screw thread
segment 235 is disposed opposite to the surrounding retaining groove
234 in the longitudinal direction, and includes a plurality of spirally
extending grooves (as shown in FIG. 2).
[0032] When the encasing member 1 is brought over the needle hub
25 and is sleeved on the syringe body 2 the male screw thread segment
128 is angularly engageable with the female screw thread segment
235 by rotation of the syringe body 2 relative to the encasing member
1 in a counterclockwise direction, until the ribs of the male screw
thread segment 128 reach ends 2351 of the grooves of the female
screw thread segment 235 so as to restrain the surrounding barrel
wall 23 from displacing along the surrounding rear segment 12 in
the longitudinal direction, thereby arresting unforced movement
of the surrounding barrel wall 23 in the position of use. Therefore,
an injection procedure of medication fluid in the accommodation
chamber 21 can be performed by pushing the stem portion 32 of the
plunger 3 towards the front end wall 24.
[0033] When the injection procedure has been completed, referring
to FIGS. 2 to 4 the surrounding barrel wall 23 is angularly moved
in a clockwise direction relative to the surrounding rear segment
12 so as to disengage the ribs of the male screw thread segment
128 from the grooves of the female screw thread segment 235 and
is displaced in the longitudinal direction remote from the surrounding
front segment 13. Subsequently, the surrounding barrel wall 23 is
pulled in the same direction so as to bring the surrounding barrel
wall 23 from the position of use to the disposal position, as shown
in FIG. 4 such that the male screw thread segment 128 engages the
surrounding retaining groove 234 thereby restraining the surrounding
barrel wall 23 from displacing along the surrounding rear segment
12. In this position as described above, the used needle cannula
26 is disposed within the encasing member 1 for safe disposal.
[0034] Referring to FIGS. 5 and 6 the second preferred embodiment
of the disposable syringe according to this invention is shown to
be similar to the aforesaid embodiment in construction. The disposable
syringe of this embodiment further includes a guideway 237 which
is disposed on the outer surrounding wall surface 233 of the surrounding
barrel wall 23 and which spirally extends to interconnect the female
screw thread segment 235 and the surrounding retaining groove 234.
As such, the male screw thread segment 128 is angularly movable
along the guideway 237 between the female screw thread segment 235
and the surrounding retaining groove 234 so as to facilitate the
displacement of the surrounding barrel wall 23 from the position
of use to the disposal position.
[0035] In addition, the surrounding rear segment 12 of the encasing
member 1 further has an outer tubular wall surface 125 radially
opposite to the inner tubular wall surface 127 and a plurality
of slots 15 which are disposed in the outer tubular wall surface
125 which are spaced apart from each other in the longitudinal
direction, and which extend through the inner tubular wall surface
127 so as to expose a portion of the surrounding barrel wall 23
of the syringe body 2.
[0036] Referring to FIG. 7 the third preferred embodiment of the
disposable syringe according to this invention is shown to be similar
to the second embodiment in construction. In this embodiment, additional
slots 16 are formed through the surrounding rear segment 12 of the
encasing member 1 and are disposed diametrically opposite to the
slots 15.
[0037] Referring to FIGS. 8 and 9 the fourth preferred embodiment
of the disposable syringe according to this invention is shown to
be similar to the aforesaid embodiments in construction. The disposable
syringe of this embodiment further comprises a catheter device 5
which includes a catheter hub 51 and a tubular catheter 52. In addition,
the rib portion 133 of the surrounding front segment 13 is shorter
than that of the aforesaid embodiment so that a front surrounding
sleeved region 134 is formed on the surrounding front segment 13
and forwardly of the rib portion 133. The catheter hub 51 includes
a surrounding hub wall which confines a duct 511 that extends along
the axis, and which has a sleeve portion 512 that is sleeved on
the front surrounding sleeved region 134 and a tip portion 513
opposite to the sleeve portion 512. The tubular catheter 52 includes
a proximate segment 521 which is disposed in the tip portion 513
and which extends along the axis to communicate fluidly with the
duct 511 and a distal segment 522 which extends from the proximate
segment 521 along the axis to project outwardly of the tip portion
513. The cannula body of the needle cannula 26 passes through the
tubular catheter 52 to permit the tip end 262 to project outwardly
of the distal segment 522. Hence, after the encasing member 1 in
which the syringe body 2 is in the disposal position, has been removed
from the catheter hub 51 a transfusion member (not shown) with
medication fluid or an empty barrel (not shown) can be connected
to the catheter hub 51 for administering the medication fluid into
a patient's vein or for drawing blood.
[0038] As illustrated, the disposable syringe of this invention
has the following advantages:
[0039] 1. By rotation of the syringe body 2 relative to the encasing
member 1 in the clockwise direction to displace the surrounding
barrel wall 23 from the position of use to the disposal position,
the used needle cannula 26 can be retracted into the encasing member
1 thereby facilitating safe disposal of the disposable syringe.
[0040] 2. The disposable syringe has a simple construction that
is easy to fabricate and assemble at a relatively low cost.
[0041] 3. Since the plunger 3 is in fit contact with the inner
surrounding wall surface 239 of the surrounding barrel wall 23 during
the injection procedure, and since there is no component part on
the inner surrounding wall surface 239 the amount of residual medication
or blood trapped in the accommodation chamber 21 can be minimized.
[0042] 4. The disposable syringe can serve as an intravenous catheter
inserting device for administering medication fluid into a patient's
vein or for drawing blood.
[0043] While the present invention has been described in connection
with what is considered the most practical and preferred embodiments,
it is understood that this invention is not limited to the disclosed
embodiments but is intended to cover various arrangements included
within the spirit and scope of the broadest interpretations and
equivalent arrangements.
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