Note: Descriptions are shown in the official language in which they were submitted.
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DISPOSABLE SYRINGE
FIELD OF THE INVENTION
This invention relates to a disposable syringe, more
particularly to a disposable syringe which enables a needle unit
S to be retracted within a barrel after use for safe disposal.
BRIEF DESCRIPTION OF THE DRAWINGS
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:
Fig. 1 is a longitudinal sectional view of a conventional
disposable syringe assembly;
Fig. 2 is an exploded perspective view of a first preferred
embodiment of a disposable syringe according to this invention
for use with a needle unit to form a syringe assembly;
Fig. 3 is a perspective view of the syringe assembly according
to the first preferred embodiment;
Fig. 4 is a longitudinal sectional view showing the syringe
assembly during use;
Fig. 5 is a longitudinal sectional view showing the syringe
assembly in a state of use;
Fig. 6 is a longitudinal sectional view showing the syringe
assembly in a state in which a head of a plunger is held by a
grip segment of a needle seat;
Fig. 7 is a longitudinal sectional view showing the syringe
assembly in a retracted state;
Fig. 8 is a longitudinal sectional view showing a second
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preferred embodiment of a disposable syringe according to this
invention for use with a needle unit to form a syringe assembly;
Fig. 9 is a longitudinal sectional view showing the syringe
assembly according to the second preferred embodiment in a state
in which a head of a plunger is held by a grip segment of a needle
seat;
Fig. 10 is a longitudinal sectional view showing the syringe
assembly in a retracted state;
Fig. 11 is an exploded longitudinal sectional view showing
a third preferred embodiment of a disposable syringe according
to this invention for use with a needle unit to form a syringe
assembly;
Fig. 12 is a longitudinal sectional view showing the syringe
assembly in a retracted state;
Fig. 13 is a fragmentary longitudinal sectional view showing
a fourth preferred embodiment of a disposable syringe according
to this invention for use with a needle unit;
Fig. 14 is a fragmentary longitudinal sectional view showing
a fifth preferred embodiment of a disposable syringe according
to this invention for use with a needle unit; and
Fig. 15 is a fragmentary longitudinal sectional view showing
a sixth preferred embodiment of a disposable syringe according
to this invention for use with a needle unit.
OF THE INVENTION
Referring to Fig. 1, a conventional disposable syringe
assembly 10 is shown to include a barrel 11, a plunger 12 and
a needle unit 13. The barrel 11 has an open neck end portion 111
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to which a needle hub 131 of the needle unit 13 is attached, and
an open rear end from which the plunger 12 is slidably inserted
into the barrel 11. A forward end 121 of the plunger 12 is snugly
fitted in, but is nevertheless slidable along the inner surface
S of the barrel 11 through a distance (L) . The needle unit 13 further
has a needle 132 extending from the needle hub 131, and a cap
133 with an open end which is fitted around an outer edge of the
needle hub 131, with the needle 132 enclosed within the cap 133.
The cap 133 is removed from the needle hub 131 when the syringe
assembly 10 is to be used, and is sleeved back after use to ensure
that the needle 132 is covered. Thereafter, the needle unit 13
is detached from the barrel 11 along with the cap 133 covering
the needle 132.
However, the medical or nursing personnel who has to handle
the conventional disposable syringe assembly 10, is exposed to
the risk of being pricked by the needle 132 when sleeving the
cap 133 back on the needle hub 131 after using the disposable
syringe assembly 10 since the dimension of the open end of the
cap 133 is relatively small. Moreover, as forward movement of
the for4vard end 121 of the plunger 12 terminates at the point
(P1) , some medicine or blood may remain within the neck end portion
111, which can cause contamination to the personnel who is
unfortunately pricked by the needle 132.
SU1~1AR7C OF TFIE INVENTION
The object of the present invention is to provide a disposable
syringe which provides greater safety in use and which eliminates
the aforesaid drawback of the prior art.
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According to this invention, the disposable syringe includes
a barrel having an inner surrounding barrel wall surface which
surrounds an axis and which confines a passage. The passage has
lower and upper open ends disposed opposite to each other in a
longitudinal direction parallel to the axis. The inner
surrounding barrel wall surface includes a larger-diameter
segment and a smaller-diameter segment which are disposed
proximate to the lower and upper open ends, respectively, and
which cooperatively form a surrounding shoulder portion
therebetween.
A tubular needle seat is insertable into the passage from the
lower open end toward the upper open end, and includes a lower
surrounding edge portion disposed to abut against the first
surrounding shoulder portion, an upper surrounding edge portion
disposed opposite to the lower surrounding edge portion in the
longitudinal direction, and a surrounding seat wall interposed
therebetween. The surrounding seat wall has an inner tubular wall
surface which surrounds the axis to confine a duct and which forms
a grip segment, and an outer tubular wall surface. The outer
tubular wall surface includes a lower segment proximate to the
lower surrounding edge portion, and an upper segment disposed
opposite to the lower segment and proximate to the upper
surrounding edge portion. When the upper surrounding edge portion
is forced to extend toward the upper open end after the tubular
needle seat is inserted into the passage, the lower segment will
be brought to a position of use, where the lower segment engages
and is retained at the smaller-diameter segment by virtue of a
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first friction force generated therebetween while the lower
surrounding edge portion abuts against the surrounding shoulder
portion. In addition, when the upper surrounding edge portion
is moved against the first friction force toward the lower open
5 end passing the larger-diameter segment, the needle seat will
be brought to a retracted position, where the lower segment and
the lower surrounding edge portion are remote from the
smaller-diameter segment and the first surrounding shoulder
portion, respectively. The outer tubular wall surface is adapted
to be fitted with a needle unit.
A plunger includes a stem portion which is disposed to be
movable in the passage and which has inner and outer segments
opposite to each other in the longitudinal direction. The outer
segment extends outwardly of the lower open end of the passage .
An actuated end extends from the outer segment so as to be actuated
to move the stem portion along the passage . A surrounding engaging
portion is retainingly sleeved on the inner segment by virtue
of a second friction force, and is in sealing contact with and
is slidable relative to the larger-diameter segment so as to be
moved with the stem portion to the position of use . A head extends
from the inner segment toward the grip segment. When the
surrounding engaging portion is brought by the inner segment to
engage the lower surrounding edge portion and is depressed by
the lower surrounding edge portion by virtue of a third force
that is generated as a consequence of continuing movement of the
inner segment towards the smaller-diameter segment and that third
force is greater than the second friction force, the surrounding
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engaging portion is retained by the lower surrounding edge portion
to thereby permit the head to move towards the grip segment of
the tubular needle seat and to be held by virtue of a fourth
friction force that is greater than the first friction force.
DETAILED DESCRIPTION OF THE PREFERRED E~ODIMENTS
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.
Referring to Figs. 2, 3 and 4, the first preferred embodiment
of the disposable syringe according to the present invention is
shown to be used with a needle unit 40 to form a syringe assembly.
The needle unit 40 includes a needle hub 42 and a needle 41 which
is securely affixed to the needle hub 42. The needle hub 42 has
a sleeved portion 423 with a plurality of longitudinally extending
frictional ribs 421 formed thereon. A tip protector 43 has an
internal sleeve end 431 which is configured to be sleeved on the
sleeved portion 423 for shielding the needle 41 and which has
a plurality of longitudinally extending frictional ribs 433 for
engaging the frictional ribs 421.
The syringe in this embodiment is shown to comprise a barrel
20, a tubular needle seat 30, and a plunger 50.
The barrel 20 has an inner surrounding barrel wall surface
221 which surrounds an axis (X) and which confines a passage 21.
The passage 21 has lower and upper open ends 211,212 which are
disposed opposite to each other in a longitudinal direction
parallel to the axis (X). The inner surrounding barrel wall
surface 221 includes a larger-diameter segment 213 arid a
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smaller-diameter segment 214 which are disposed proximate to the
lower and upper open ends 211,212, respectively, and which
cooperatively form a first surrounding shoulder portion 215
therebetween. A finger flange 23 is disposed on an outer
S surrounding barrel wall surface 222 of the barrel 20 at the lower
open end 211. The smaller-diameter segment 214 is formed with
a retaining groove 223 proximate to the f first surrounding shoulder
portion 215, and an axially extending friction spline portion
216 remote from the first surrounding shoulder portion 215. A
protruding ring 217 is formed on and projects inwardly and
radially from the larger-diameter segment 213 adjacent to the
lower open end 211.
The tubular needle seat 30 is disposed to be insertable into
the passage 21 from the lower open end 211 toward the upper open
end 212. The needle seat 30 includes a lower surrounding edge
portion 33 disposed to abut against the first surrounding shoulder
portion 215 and having an outer surrounding surface 333 which
abuts sealingly against the larger-diameter segment 213 , an upper
surrounding edge portion 321 disposed opposite to the lower
surrounding edge portion 33 in the longitudinal direction, and
a surrounding seat wall 32 interposed therebetween.
The seat wall 32 has an inner tubular wall surface 324 which
surrounds the axis (X) to confine a duct 31. The duct 31 has a
diameter that gradually decreases from the lower surrounding edge
portion 33 to the upper surrounding edge portion 321. The inner
tubular wall surface 324 forms a grip segment . In this embodiment,
the grip segment includes a concave portion 326 which extends
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inwardly from the inner tubular wall surface 324 in radial
directions relative to the axis (X) to form a second surrounding
shoulder portion 329 that is adjacent to the lower surrounding
edge portion 33.
The seat wall 32 further has an outer tubular wall surface
325 which includes lower and upper segments 322,323. The lower
segment 322 is proximate to the lower surrounding edge portion
33, and has a retaining protrusion 327 formed thereon. When the
upper surrounding edge portion 321 is forced to extend outwardly
of the upper open end 212 of the barrel 20 after the tubular needle
seat 30 is inserted into the passage 21, the lower segment 322
will be brought to a position of use, as shown in Fig. 4, where
the lower segment 322 engages and is retained at the
smaller-diameter segment 214 by virtue of a first friction force
generated as a result of retaining engagement of the retaining
protrusion 327 in the retaining groove 223, while an upper edge
surface 331 of the lower surrounding edge portion 33 abuts against
the first surrounding shoulder portion 215 of the barrel 20. The
lower segment 322 further has an axially extending friction spline
portion 328 which cooperates with the friction spline portion
216 of the smaller-diameter segment 214 to fornn a spline member
so as to prevent relative rotation between the needle seat 30
and the barrel 20. The upper segment 323 is disposed opposite
to the lower segment 322 and proximate to the upper surrounding
edge portion 321, and is adapted to be sleeved over by the needle
hub 42 of the needle unit 40 so as to communicate the duct 31
of the needle seat 30 with the needle hub 42.
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The plunger 50 includes a stem portion 50a which is movable
in the passage 21 of the barrel 20. The stem portion 50a has a
plurality of wing plates 53 angularly displaced from one another,
a surrounding flange 51 disposed on upper edges of the wing plates
S 53, a connecting shank 54 extending from the surrounding flange
51, and a retaining protrusion 542 . The wing plates 53 are tapered
downwardly. On the other hand, the stem portion 50a includes inner
and outer segments 502,501 opposite to each other in the
longitudinal direction. The outer segment 501 extends outwardly
of the lower open end 211 of the barrel 20. An actuated end 52,
which is a thumb rest, extends from the outer segment 501 so as
to be actuated to move the stem portion 50a along the passage
21.
The plunger 50 further includes a head 50b which has a tapered
surrounding abutting portion 541 that extends from the retaining
protrusion 542 of the inner segment 502 toward the grip segment
of the needle seat 30, and a spindle portion 55 which extends
upwardly from the surrounding abutting portion 541 along the axis
(X) and which terminates at two split halves 552,553 that are
spaced apart from each other in a direction transverse to the
longitudinal direction with a concave space 551 inbetween. The
split halves 552,553 respectively have upper terminal anchoring
edges 554,555. Preferably, the spindle portion 55 has an outer
diameter which decreases from the surrounding abutting portion
541 toward the split halves 552,553. Moreover, the surrounding
abutting portion 541 and the retaining protrusion 542 are
configured to be substantially hollow so as to provide greater
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flexibility.
A deformable surrounding engaging portion 60, preferably made
of an elastic material, is retainingly sleeved on the whole
retaining protrusion 542 of the inner segment 502 and a portion
5 of the surrounding abutting portion 541 to generate a second
friction force. The surrounding engaging portion 60 has upper
and lower end faces 64,65 opposite to each other in the
longitudinal direction and proximate to and distal from the lower
surrounding edge portion 33 of the needle seat 30, respectively,
10 and an outer surrounding surface 63 disposed therebetween. The
lower end face 65 is distal from the surrounding flange 51 by
a space (S) . The outer surrounding surface 63 sealingly contacts
and is slidable relative to the larger-diameter segment 213 of
the barrel 20 so as to be moved with the stem portion 50a.
Preferably, the outer surrounding surface 63 is concaved toward
the axis (X) to decrease contact area between the outer
surrounding surface 63 and the larger-diameter segment 213 so
as to facilitate sliding movement of the surrounding engaging
portion 60 relative to the larger-diameter segment 213.
With reference to Fig. 5, in use, the plunger 50 is pressed
forwardly to push the upper end face 64 of the surrounding engaging
portion 60 to abut against a lower edge surface 332 of the lower
surrounding edge portion 33 of the needle seat 30. Since the
spindle portion 55 is configured to be tapered upwardly and to
match with the inner tubular wall surface 324 of the needle seat
30, drug solution in the passage 21 can almost be completely
injected via the needle unit 40.
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Subsequently, referring to Fig. 6, when the plunger 50 is
further moved forward by a third force towards the smaller-
diameter segment 214 against the second friction force between
the inner segment 502 and the surrounding engaging portion 60,
the surrounding engaging portion 60 is deformed by the lower
surrounding edge portion 33, thereby decreasing the space (S)
and permitting the surrounding abutting portion 541 of the head
50b to move in the concave portion 326 of the needle seat 30 to
abut against the second surrounding shoulder portion 329.
Meanwhile, the split halves 552,553 of the spindle portion
55 are pressed by the inner tubular wall surface 324 to move
towards each other against a biasing action when the split halves
552 , 553 are moved towards the upper surrounding edge portion 321.
Once the split halves 552,553 are moved beyond the upper
surrounding edge portion 321, the upper terminal anchoring edges
554,555 will engage the upper surrounding edge portion 321 to
generate a friction force that combines with the friction force
between the surrounding abutting portion 541 and the second
surrounding shoulder portion 329 to form a fourth friction force
that is greater than the first friction force between the
retaining protrusion 327 and the retaining groove 223.
After use, referring to Fig. 7, the outer segment 501 of the
plunger 50 is pulled backward to be remote from the finger flange
23 so that the needle seat 30, on which the used needle unit 40
is mounted, is retracted into the passage 21 via the upper open
end 212 to bring the upper surrounding edge portion 321 to a
retracted position. When the surrounding flange 51 abuts against
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the protruding ring 217, further movement of the plunger 50 is
prevented, thereby restraining the surrounding engaging portion
60 from being moved out of the lower open end 211. In this state,
the used needle unit 40 can be enclosed in the passage 21 of the
barrel 20 for disposal.
Consequently, chances that the user may be accidentally
pricked or pierced by the needle 41 are slim. The safety in use
and disposal is thus enhanced.
Furthermore, the wing plates 53 at the inner segment 502 have
a weakening area 531 disposed proximate to the surrounding flange
51. As such, when the plunger 50 is retracted to push the
surrounding flange 51 to abut against the protruding ring 217,
the weakening area 531 extends outwardly of the lower open end
211 so as to ease breaking of the stem portion 50a off the plunger
50 at the weakening area 531 for convenient disposal.
Ref erring to Fig . 8 , the second pref erred embodiment of the
disposable syringe according to this invention is shown to be
similar to the aforesaid embodiment in construction. The
differences therebetween reside in that the spindle portion in
the aforesaid embodiment is dispensed with. An elastic
surrounding engaging portion 60 is retainingly sleeved on the
whole retaining protrusion 742 and a portion of the surrounding
abutting portion 741. As such, when the surrounding engaging
portion 60 is brought by the stem portion 73 of the plunger 70
upwardly to engage and to be depressed by the lower surrounding
edge portion 33 of the needle seat 30, the surrounding engaging
portion 60 is retained by the lower surrounding edge portion 33,
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thereby permitting the surrounding abutting portion 741 to be
retained in the concave portion 326, as shown in Fig. 9. Hence,
the needle seat 30 and the needle unit 40 can be retracted into
the passage 21 of the barrel 20 after an injection procedure to
permit breaking of the stem portion 73 of the plunger 70 at a
weakening area 731 for safe disposal, as shown in Fig. 10.
Referring to Figs . 11 and 12 , the third pref erred embodiment
of the disposable syringe according to this invention is shown
to be similar to the aforesaid embodiments in construction. The
differences therebetween reside in that a tubular needle seat
30 has a duct 31 with a relatively small diameter at the upper
segment 323 so as to engage fittingly the needle 41. Thus, the
needle hub 42 can be eliminated.
Moreover, a barrel 20 has an outer surrounding wall surface
222 with a sleeved portion 2221 which is disposed proximate to
the upper open end 212 to replace the sleeved portion 423 shown
in Fig. 2, and which has a plurality of friction ribs 224 formed
thereon. Thus, a tip protector 43, which has a plurality of
frictional ribs 433 formed on an internal sleeve end 431 thereof,
can be sleeved f fittingly on the sleeved portion 2221 for shielding
the needle 41.
In the syringe assembly of this embodiment, the number of
components is decreased. Similarly, the needle seat 30 and the
needle 41 can be retracted into the passage 21 of the barrel 20
after an injection procedure.
Referring to Fig. 13, the fourth preferred embodiment of the
disposable syringe with a similar construction of the aforesaid
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embodiments, is used for an extremely small injection volume,
such as 1 ml. Thus, the dimensions of the barrel 20, the needle
seat 30, the needle 41, the plunger 70, and the deformable
surrounding engaging portion 60 are smaller than those of the
aforesaid embodiments.
Referring to Figs. 14 and 15, the fifth and sixth preferred
embodiments of the disposable syringe according to this invention
are shown to be similar to the third and fourth embodiments in
construction, respectively. The differences therebetween reside
in that the upper open end 212 has a surrounding edge wall 219
which extends from the smaller-diameter segment 214 of the inner
surrounding barrel wall surface 221 of the barrel 20 toward the
axis (X) and which confines a through hole 210 that surrounds
the axis (X) . As such, the needle 41 can pass through the through
hole 210 and outwardly of the upper open end 212. The sixth
preferred embodiment shown in Fig. 15 is similar to the fifth
preferred embodiment in construction, but is used for an extremely
small injection volume, such as 1 ml.
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.
