Abstrict A disposable syringe includes a tubular barrier member retained
in a rear passageway of a barrel. A tubular needle seat for fixing
a needle cannula is retained on the barrier member, and abuts against
an abutment wall in the front passageway of the barrel while the
needle cannula is disposed outwardly of the barrel. A plunger is
slidable in the rear passageway, and has a seal member to seal a
cavity confined in a plunger body and containing a fluid at a reduced
pressure. When a pushing force applied to the plunger body moves
the barrier member against the first and second frictional forces,
the needle seat is released, and the seal member is ruptured, so
that the needle seat and the needle cannula are suctioned into the
cavity due to the pressure difference between the ambient atmosphere
and the reduced pressure.
Claims We claim:
1. A disposable syringe, comprising: a needle cannula; a barrel
having an inner surrounding barrel wall surface which surrounds
an axis and which confines a passage, said passage having rearward
and forward openings which are disposed opposite to each other in
a longitudinal direction parallel to the axis, said inner surrounding
barrel wall surface including a larger-diameter segment and a smaller-diameter
segment which confine rear and front passageways, respectively,
and which are disposed proximate to said rearward and forward openings,
respectively, to form a surrounding shoulder portion therebetween,
said smaller-diameter segment including a front surrounding region
and a rear surrounding region which is proximate to said surrounding
shoulder portion and which is of a larger dimension than that of
said front surrounding region so as to form a surrounding abutment
wall therebetween, said larger-diameter segment including proximate
and distal surrounding regions opposite to each other in the longitudinal
direction and respectively proximate to and distal from said surrounding
shoulder portion, said proximate surrounding region having a retaining
area which is spaced apart from said surrounding shoulder portion
in the longitudinal direction; a tubular barrier member which includes
front and rear surrounding edge portions opposite to each other
in the longitudinal direction and which includes inner and outer
barrier wall surfaces opposite to each other and surrounding the
axis, said outer barrier wall surface, in a position of use, being
retained at said retaining area by virtue of a first frictional
force generated therebetween while in water-tight engagement with
said proximate surrounding region, thereby partitioning said rear
passageway into a compressible chamber which confronts said surrounding
shoulder portion, and an accommodation chamber which confronts said
rear surrounding edge portion, said inner barrier wall surface having
a grip segment; a tubular needle seat including a hub portion which
is disposed to fix said needle cannula therein, and which has a
surrounding front end wall extending radially relative to the axis,
a surrounding gripped portion which extends from said hub portion
in the longitudinal direction and away from said surrounding front
end wall, and which is retained at said grip segment by virtue of
a second frictional force generated between said surrounding gripped
portion and said grip segment when said surrounding front end wall
abuts against said surrounding abutment wall and when said needle
cannula is disposed outwardly of said forward opening, and an anchoring
portion extending from said surrounding gripped portion in the longitudinal
direction and away from said hub portion; and a plunger which, in
the use position, is disposed to be movable in said accommodation
chamber, said plunger including a plunger body which includes a
top end wall disposed movably to abut against said rear surrounding
edge portion of said tubular barrier member, and a bottom end wall
disposed opposite to said top end wall in the longitudinal direction
and extending outwardly of said rearward opening so as to be manually
operable, said top end wall having an inner peripheral edge portion
which surrounds the axis and which defines a cavity therein, said
cavity extending along the axis and towards said bottom end wall
to contain a fluid at a reduced pressure, and a seal member disposed
to be sealingly attached to said inner peripheral edge portion along
a sealing line so as to trap said fluid in said cavity, said sealing
line being configured such that when a pushing force greater than
the first and second frictional forces, is manually applied to said
bottom end wall to move said top end wall to abut against said rear
surrounding edge portion of said tubular barrier member, said tubular
barrier member is pushed to move towards said surrounding shoulder
portion to force said grip segment to disengage from said surrounding
gripped portion, so that said anchoring portion, which remains fixedly
in place due to abutment of said surrounding front end wall against
said surrounding abutment wall, is exposed to and is impacted by
an impact force from said seal member along the axis so that said
sealing line is ruptured, thereby releasing said seal member from
said plunger body, and thereby permitting said tubular needle seat
to be forced into engagement with said seal member to be subsequently
suctioned into said cavity due to a pressure difference between
the ambient atmosphere and the reduced pressure.
2. The disposable syringe of claim 1 wherein said barrel has an
outer surrounding barrel wall surface which has a rib portion extending
in the longitudinal direction and disposed at said front surrounding
region adjacent to said forward opening, said disposable syringe
further comprising a tip protector which has a sleeve end disposed
to sleeve on said outer surrounding barrel 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 surrounding barrel wall surface, thereby ensuring secure
shielding of said needle cannula.
3. The disposable syringe of claim 1 wherein one of said proximate
surrounding region in said retaining area and said outer barrier
wall surface is formed with a first retaining groove, and the other
one of said proximate surrounding region in said retaining area
and said outer barrier wall surface is formed with a first retaining
protrusion which engages retainingly said first retaining groove
to generate the first frictional force when said outer barrier wall
surface is in the position of use, and wherein one of said grip
segment of said inner barrier wall surface and said surrounding
gripped portion of said tubular needle seat is a second retaining
groove, and the other one of said grip segment of said inner barrier
wall surface and said surrounding gripped portion of said tubular
needle seat is a second retaining protrusion which engages retainingly
said second retaining groove to generate the second frictional force
when said surrounding front end wall abuts against said surrounding
abutment wall.
4. The disposable syringe of claim 3 wherein said surrounding
front end wall includes a sealing member which is in air-tight engagement
with said rear surrounding region so as to maintain air-tightness
of said compressible chamber, said compressible chamber being filled
with a fluid, said hub portion of said tubular needle seat having
a plurality of through holes which are distal from said surrounding
front end wall in the longitudinal direction, which are formed therethrough
to be in fluid communication with said compressible chamber, and
which extend in the longitudinal direction such that when said tubular
barrier member is moved towards said surrounding shoulder portion,
said fluid is forced to flow into said through holes, thereby enforcing
said anchoring portion to move toward said cavity so as to increase
the impact force.
5. The disposable syringe of claim 4 wherein said sealing member
is made from an elastomeric material, and has an axial hole extending
along the axis to engage fittingly said needle cannula therein.
6. The disposable syringe of claim 4 wherein said inner barrier
wall surface is formed with a deformable sealing portion which is
in air-tight engagement with said hub portion of said tubular needle
seat.
7. The disposable syringe of claim 1 further comprising a biasing
member disposed in said front surrounding region to bias said tubular
needle seat toward said seal member.
8. The disposable syringe of claim 4 further comprising a biasing
member disposed in said front surrounding region to bias said tubular
needle seat toward said seal member.
9. The disposable syringe of claim 3 wherein said front surrounding
edge portion has a surrounding groove surrounding the axis so that
said inner barrier wall surface more is deformable in radial directions
relative to the axis,
10. The disposable syringe of claim 3 wherein said inner barrier
wall surface is divergent from said grip segment to said front surrounding
edge portion to prevent friction contact between said inner barrier
wall surface and said hub portion of said tubular needle seat when
said tubular needle seat is suctioned into said cavity.
11. The disposable syringe of claim 1 wherein said plunger body
has a surrounding sealing ring which is disposed adjacent to said
top end wall, which surrounds the axis, and which is slidable on
and in air-tight engagement with said larger-diameter segment of
said inner surrounding barrel wall surface.
12. The disposable syringe of claim 1 wherein said seal member
has an engaging recess which confronts said anchoring portion and
which extends in the longitudinal direction so as to engage said
anchoring portion when said seal member is released from said plunger
body, and a third retaining groove which is disposed in said engaging
recess and which extends in a radial direction relative to the axis,
said anchoring portion having a third retaining protrusion which
is disposed to be retained in said third retaining groove when said
anchoring portion engages said engaging recess such that said seal
member, together with said tubular needle seat, is suctioned into
said cavity.
13. The disposable syringe of claim 12 wherein said cavity includes
front and rear cavity segments which are disposed proximate to said
top and bottom end walls, respectively, and which have smaller and
larger inner diameters, respectively, said seal member having an
outer surrounding seal surface which is configured to be kept in
slidable contact and air-tight engagement with said inner peripheral
edge portion when said seal member is suctioned in said front cavity
segment.
14. The disposable syringe of claim 13 wherein said plunger further
includes a plurality of barrier ribs, each of which is disposed
adjacent to said bottom end wall and which extends from said inner
peripheral edge portion radially and toward the axis so as to trap
said tubular needle seat when said tubular needle seat is forced
towards said bottom end wall.
15. The disposable syringe of claim 13 wherein said plunger body
further includes an outer peripheral wall surface, and a plurality
of rib plates which are formed on said outer peripheral wall surface
at said front cavity segment, and which are flush with said outer
peripheral wall surface at the rear cavity segment.
16. The disposable syringe of claim 1 wherein said inner surrounding
barrel wall surface is spaced apart from said needle cannula in
radial directions relative to the axis at said forward opening to
define a surrounding clearance therebetween.
17. The disposable syringe of claim 16 further comprising a plurality
of ribs which are disposed on said inner surrounding barrel wall
surface and which are angularly displaced from one another, each
of said ribs extending towards said needle cannula, an air duct
being formed between two adjacent ones of said ribs to communicate
said passage with the ambient atmosphere.
18. The disposable syringe of claim 1 further comprising two injection
limiting protrusions which are disposed on said plunger body adjacent
to said bottom end wall and said larger-diameter segment adjacent
to said rearward opening respectively, and which abut against each
other when said top end wall reaches said rear surrounding edge
portion so as to limit an extent of an injection course.
19. The disposable syringe of claim 1 wherein said bottom end
wall has an opening which is in fluid communication with said cavity,
said plunger further including an end cap which is disposed to cover
said opening and to be in air-tight engagement with said bottom
end wall.
20. A disposable syringe, comprising: a needle cannula; a barrel
having an inner surrounding barrel wall surface which surrounds
an axis and which confines a passage, said passage having rearward
and forward openings which are disposed opposite to each other in
a longitudinal direction parallel to the axis, said inner surrounding
barrel wall surface including a larger-diameter segment and a smaller-diameter
segment which confine rear and front passageways, respectively,
and which are disposed proximate to said rearward and forward openings,
respectively, to form a surrounding shoulder portion therebetween,
said smaller-diameter segment including a front surrounding region
and a rear surrounding region which is proximate to said surrounding
shoulder portion and which is of a larger dimension than that of
said front surrounding region so as to form a surrounding abutment
wall therebetween, said larger-diameter segment including proximate
and distal surrounding regions opposite to each other in the longitudinal
direction and respectively proximate to and distal from said surrounding
shoulder portion, said proximate surrounding region having a retaining
area which is spaced apart from said surrounding shoulder portion
in the longitudinal direction; a tubular barrier member which includes
front and rear surrounding edge portions opposite to each other
in the longitudinal direction and which includes inner and outer
barrier wall surfaces opposite to each other and surrounding the
axis, said outer barrier wall surface, in a position of use, being
retained at said retaining area by virtue of a first frictional
force generated therebetween while in water-tight engagement with
said proximate surrounding region, thereby partitioning said rear
passageway into a compressible chamber which confronts said surrounding
shoulder portion, and an accommodation chamber which confronts said
rear surrounding edge portion, said inner barrier wall surface having
a grip segment, said compressible chamber being filled with a fluid;
a tubular needle seat including a hub portion which is disposed
to fix said needle cannula therein, and which has a surrounding
front end wall extending radially relative to the axis, said surrounding
front end wall including a sealing member which is in air-tight
engagement with said rear surrounding region, said inner barrier
wall surface of said tubular barrier member being formed with a
deformable sealing portion which is in air-tight engagement with
said hub portion of said tubular needle seat so as to maintain air-tightness
of said compressible chamber, said hub portion further having a
plurality of through holes which extend from said surrounding front
end wall in the longitudinal direction and which are formed therethrough
to be in fluid communication with said compressible chamber; a surrounding
gripped portion which extends from said hub portion in the longitudinal
direction and away from said surrounding front end wall, and which
is retained at said grip segment by virtue of a second frictional
force generated between said surrounding gripped portion and said
grip segment when said sealing member abuts against said surrounding
abutment wall and when said needle cannula is disposed outwardly
of said forward opening, and an anchoring portion extending from
said surrounding gripped portion in the longitudinal direction and
away from said hub portion; and a plunger which, in the use position,
is disposed to be movable in said accommodation chamber, said plunger
including a plunger body which includes a top end wall disposed
movably to abut against said rear surrounding edge portion of said
tubular barrier member, and a bottom end wall disposed opposite
to said top end wall in the longitudinal direction and extending
outwardly of said rearward opening so as to be manually operable,
said top end wall having an inner peripheral edge portion which
surrounds the axis and which defines a cavity therein, said cavity
extending along the axis and towards said bottom end wall, and a
seal member attached to said inner peripheral edge portion along
a line, said sealing line being configured such that when a pushing
force greater than the first and second frictional forces, is manually
applied to said bottom end wall to move said top end wall to abut
against said rear surrounding edge portion of said tubular barrier
member, said tubular barrier member is pushed to move towards said
surrounding shoulder portion to compress said fluid in said compressible
chamber into said through holes, thereby generating a pressure force
in the longitudinal direction on said surrounding gripped portion
and forcing said grip segment to disengage from said surrounding
gripped portion, so that said anchoring portion, which remains fixedly
in place due to abutment of said sealing member against said surrounding
abutment wall, is exposed to and is impacted by an impact force
from said seal member along the axis such that said line is ruptured,
thereby releasing said seal member from said plunger body, and thereby
permitting said tubular needle seat to be forced by the pressure
force into engagement with said seal member to be subsequently moved
into said cavity.
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 a plunger cavity having a reduced pressure therein.
[0003] 2. Description of the Related Art
[0004] Referring to FIGS. 1 and 2 U.S. Pat. No. 5176640 discloses
a hypodermic injection syringe 10 which includes a barrel 11 a
base 12 fixed to an open front end 111 of the barrel 11 a needle
cannula 13 having a rear needle end 132 that extends into the barrel
11 through the base 12 along an axis and that has an engagement
recess 131 and a plunger 18 slidable within the barrel 11. The
plunger 18 includes a hollow shaft 14 with a vacuum chamber 141
and a head which has an elastic rubber ring 16 with a channel that
is closed by a disc 161 and a plug 15 with a tube forcibly inserted
into the channel of the ring 16 and secured to the shaft 14. A piston
17 is slidable in a sealed manner within the chamber 141 and is
provided with an engaging rod 172 formed with an elastic flap 171
on a front end thereof.
[0005] In use, when the plunger 18 is about to finish its injection
stroke, the disc 161 is lacerated by the rear needle end 132 the
rod 172 then engages the needle 13 by engagement of the flap 171
and the engagement recess 131. In this state, under the action of
vacuum present in the chamber 141 the rod 172 and the needle 13
are sucked into the chamber 141.
[0006] Since the needle 13 can be retained in the chamber 141 of
the plunger 18 for safety disposal, the following drawbacks arise:
[0007] 1. The laceration of the disc 161 may occur when the injection
procedure of the syringe 10 is not finished. Thus, some medicine
or blood may will remain within the barrel 11 to result in contamination.
[0008] 2. In order to smoothly suck the needle 13 into the chamber
141 the securing of the needle 13 to the base 12 cannot be very
tight. However, insufficient securing of the needle 13 will result
in movement or removal of the needle 13 during the injection procedure.
SUMMARY OF THE INVENTION
[0009] The object of the present invention is to provide a disposable
syringe which can prevent trapping of medicine or blood therein
after injection and which can be operated easily and smoothly to
retract a used needle within a plunger.
[0010] According to this invention, the disposable syringe includes
a needle cannula, a barrel, a tubular barrier member, a tubular
needle seat, and a plunger. The barrel has an inner surrounding
barrel wall surface surrounding an axis and confining a passage
with opposite rearward and forward openings. The inner surrounding
barrel wall surface includes a larger-diameter segment and a smaller-diameter
segment which confine rear and front passageways, respectively,
to form a surrounding shoulder portion therebetween. The smaller-diameter
segment includes a smaller front surrounding region and a larger
rear surrounding region to form a surrounding abutment wall therebetween.
The larger-diameter segment includes proximate and distal surrounding
regions respectively proximate to and distal from the surrounding
shoulder portion. The proximate surrounding region has a retaining
area spaced apart from the surrounding shoulder portion.
[0011] The tubular barrier member includes front and rear surrounding
edge portions, and inner and outer barrier wall surfaces. The outer
barrier wall surface is retained at the retaining area by virtue
of a first frictional force generated therebetween while in water-tight
engagement with the proximate surrounding region, thereby partitioning
the rear passageway into a compressible chamber confronting the
surrounding shoulder portion, and an accommodation chamber confronting
the rear surrounding edge portion. The inner barrier wall surface
has a grip segment.
[0012] The tubular needle seat includes a hub portion disposed
to fix the needle cannula therein. The hub portion has a surrounding
front end wall, a surrounding gripped portion and an anchoring portion.
The surrounding gripped portion is retained at the grip segment
by virtue of a second frictional force generated therebetween when
the surrounding front end wall abuts against the surrounding abutment
wall and when the needle cannula is disposed outwardly of the forward
opening.
[0013] The plunger is movable in the accommodation chamber, and
includes a plunger body and a seal member. The plunger body includes
a top end wall disposed movably to abut against the rear surrounding
edge portion of the tubular barrier member, and a bottom end wall
extending outwardly of the rearward opening so as to be manually
operable. The top end wall has an inner peripheral edge portion
surrounding the axis to define a cavity therein. The cavity extends
along the axis and towards the bottom end wall to contain a fluid
at a reduced pressure. The seal member is disposed to be sealingly
attached to the inner peripheral edge portion along a sealing line
so as to trap the fluid in the cavity.
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 a sectional view of a conventional disposable
syringe during use;
[0016] FIG. 2 shows the conventional disposable syringe of FIG.
1 after use, showing a needle cannula in a retracted state;
[0017] FIG. 3 is an exploded sectional view of a first preferred
embodiment of a disposable syringe according to this invention;
[0018] FIG. 4 is a sectional view of the first preferred embodiment
during use;
[0019] FIG. 5 is a sectional view showing a portion of the first
preferred embodiment in detail;
[0020] FIG. 6 is a sectional view showing the portion of the first
preferred embodiment after use;
[0021] FIG. 7 is a sectional view of the first preferred embodiment,
showing a needle cannula in a retracted state;
[0022] FIG. 8 is a cross-sectional view of a barrel shown in FIG.
5 taken along lines 8-8 thereof;
[0023] FIG. 9 is a sectional view of a second preferred embodiment
of the disposable syringe according to this invention;
[0024] FIG. 10 is a sectional view of the second preferred embodiment,
showing a needle cannula in a retracted state;
[0025] FIG. 11 is a sectional view of a third preferred embodiment
of the disposable syringe according to this invention;
[0026] FIG. 12 is a sectional view showing a portion of the third
preferred embodiment in detail;
[0027] FIG. 13 is a sectional view of the third preferred embodiment,
showing a needle cannula in a retracted state;
[0028] FIG. 14 is a sectional view of a fourth preferred embodiment
of the disposable syringe according to this invention;
[0029] FIG. 15 is a sectional view of the fourth preferred embodiment,
showing a needle cannula in a retracted state;
[0030] FIG. 16 is a sectional view of a fifth preferred embodiment
of the disposable syringe according to this invention;
[0031] FIG. 17 is a fragmentary sectional view of a sixth preferred
embodiment of the disposable syringe according to this invention;
[0032] FIG. 18 is a fragmentary sectional view of a seventh preferred
embodiment of the disposable syringe according to this invention;
[0033] FIG. 19 is a fragmentary sectional view of an eighth preferred
embodiment of the disposable syringe according to this invention;
[0034] FIG. 20 is a sectional view of a ninth preferred embodiment
of the disposable syringe according to this invention; and
[0035] FIG. 21 is a fragmentary sectional view showing an alternate
embodiment of a sealing member of a plunger of the disposable syringe
of this invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] 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.
[0037] Referring to FIGS. 3 4 and 5 the first preferred embodiment
of the disposable syringe according to the present invention is
shown to comprise a barrel 20 a tubular barrier member 30 a plunger
50 and a needle assembly 40 including a needle cannula 42 a tubular
needle seat 41 and a tip protector 43.
[0038] The barrel 20 has an inner surrounding barrel wall surface
which surrounds an axis (X) and which confines a passage. The passage
has rearward and forward openings 232231 which are disposed opposite
to each other in a longitudinal direction parallel to the axis (X).
The inner surrounding barrel wall surface includes a larger-diameter
segment 22 and a smaller-diameter segment 21 which confine rear
and front passageways 221210 respectively, and which are disposed
proximate to the rearward and forward openings 232231 respectively,
to form a surrounding shoulder portion 222 therebetween. The smaller-diameter
segment 21 includes a front surrounding region 211 and a rear surrounding
region 212 which is proximate to the surrounding shoulder portion
222 and which is of a larger dimension than that of the front surrounding
region 211 so as to form a surrounding abutment wall 213 therebetween.
The larger-diameter segment 22 includes proximate and distal surrounding
regions opposite to each other in the longitudinal direction and
respectively proximate to and distal from the surrounding shoulder
portion 222. The proximate surrounding region has a retaining area
which is spaced apart from the surrounding shoulder portion 222
in the longitudinal direction. In this embodiment, an annular first
retaining protrusion 24 is formed on the proximate surrounding region
in the retaining area. An annular injection limiting protrusion
25 is formed on the distal surrounding region adjacent to the rearward
opening 232. An outer surrounding barrel wall surface 23 of the
barrel 20 has a rib portion 235 which extends in the longitudinal
direction and which is disposed at the front surrounding region
211 adjacent to the forward opening 231.
[0039] The tubular barrier member 30 includes front and rear surrounding
edge portions 3334 opposite to each other in the longitudinal direction
and which includes inner and outer barrier wall surfaces 3135 opposite
to each other and surrounding the axis (X). The outer barrier wall
surface 35 is formed with an annular first retaining groove 350
such that in a position of use, the first retaining protrusion 24
is retained in the first retaining groove 350 in a water-tight manner
so as to generate a first frictional force therebetween, thereby
partitioning the rear passageway 221 into a compressible chamber
26 which confronts the surrounding shoulder portion 222 and an
accommodation chamber 27 which confronts the rear surrounding edge
portion 34. The inner barrier wall surface 31 has a second retaining
groove 320 which serves as a grip segment. As shown in FIG. 5 the
front surrounding edge portion 33 has a surrounding groove 39 surrounding
the axis (X) such that the inner barrier wall surface 31 is more
deformable in radial directions relative to the axis (X). In addition,
the inner barrier wall surface 31 is divergent from the second retaining
groove 320 to the front surrounding edge portion 33 so as to prevent
friction contact between the inner barrier wall surface 31 and the
hub portion 410.
[0040] The tubular needle seat 41 includes a hub portion 410 which
is disposed to fix the needle cannula 42 therein, and which has
a surrounding front end wall 411 that extends radially relative
to the axis (X). An annular second retaining protrusion 414 extends
from the hub portion 410 in the longitudinal direction and away
from the surrounding front end wall 411 to form a surrounding gripped
portion. which is retained in the second retaining groove 320 to
generate a second frictional force when the surrounding front end
wall 411 abuts against the surrounding abutment wall 213 and when
the needle cannula 42 is disposed outwardly of the forward opening
231. An anchoring portion 412 extends from the second retaining
protrusion 414 in the longitudinal direction and away from the hub
portion 410 and has an annular third retaining protrusion 415 formed
thereon (see FIG. 5).
[0041] The tip protector 43 has a sleeve end 433 which is disposed
to sleeve on the outer surrounding barrel wall surface 23. The sleeve
end 433 includes a groove portion which mates with the rib portion
235 to result in a splined engagement between the tip protector
43 and the outer surrounding barrel wall surface 23 thereby ensuring
secure shielding of the needle cannula 42. Moreover, as the sleeve
end 433 of the tip protector 43 is provided with the groove portion
to engage the rib portion 235 on the outer surrounding barrel wall
surface 23 the sleeve end 433 has a relatively large inner diameter,
thereby enhancing safety during sleeving of the tip protector 43
onto the outer surrounding barrel wall surface 23.
[0042] The plunger 50 is disposed to be slidable in the accommodation
chamber 27 and includes a plunger body 54 an end cap 57 and a
seal member 56.
[0043] The plunger body 54 includes an open top end wall 541 which
is disposed movably to abut against the rear surrounding edge portion
34 of the tubular barrier member 30 and an open bottom end wall
542 which is disposed opposite to the top end wall 541 in the longitudinal
direction and which extends outwardly of the rearward opening 232.
The plunger body 54 has an inner peripheral edge portion 543 which
surrounds the axis (X) and which defines a cavity 500 therein. The
cavity 500 extends along the axis (X) from the top end wall 541
to the bottom end wall 542 to contain a fluid at a reduced pressure.
Preferably, the cavity 500 is in a substantially vacuum state. In
this embodiment, the cavity 500 includes a smaller-diameter front
cavity segment 51 and a larger-diameter rear cavity segment 52 which
are disposed proximate to the top and bottom end walls 541542
respectively, to form a shoulder portion 55 therebetween. Preferably,
an enlarged cavity segment 53 is disposed rearwardly of the rear
cavity segment 52 and outwardly of the rearward opening 232 so as
to be manually operable. A plurality of rib plates 549 are formed
on an outer peripheral wall surface 544 of the plunger body 54 at
the front cavity segment 51 and are flush with the outer peripheral
wall surface 544 at the rear cavity segment 52. An annular injection
limiting protrusion 545 is formed on the outer peripheral wall surface
544 at the rear cavity segment 52 adjacent to the enlarged cavity
segment 53 and is disposed to abut against the injection limiting
protrusion 25 when the top end wall 541 reaches the rear surrounding
edge portion 34 so as to indicate completion of an injection course.
[0044] Moreover, an annular anchoring protrusion 546 and an annular
retaining flange 547 are formed adjacent to the top end wall 541.
A surrounding sealing ring 59 is made of a deformable material,
and is sleeved retainingly over the outer peripheral wall surface
544 adjacent to the top end wall 541 by means of the anchoring protrusion
546 and the retaining flange 547.
[0045] The end cap 57 includes an outer surrounding wall 571 which
engages threadedly a threaded segment 548 of the outer peripheral
wall surface 544 an inner surrounding wall 572 which is attached
to the inner peripheral edge portion 543 and an end cap wall 573
which is connected to the outer and inner surrounding walls 571572
and which covers an opening in the bottom end wall 542 in an air-tight
sealing manner.
[0046] A plurality of barrier ribs 58 are formed between the rear
cavity segment 52 and the enlarged cavity segment 53. Each barrier
rib 58 extends from the inner peripheral edge portion 543 radially
and toward the axis (X).
[0047] The seal member 56 is disposed to be sealingly attached
to the inner peripheral edge portion 543 at the top end wall 541
along an annular sealing line 566 so as to trap the fluid in the
cavity 500 so as to maintain the reduced pressure (the substantially
vacuum state in this embodiment). In the embodiment shown in FIG.
3 the seal member 56 is formed on the inner peripheral edge portion
543. Alternately, referring to FIG. 21 the sealing member 56 is
disposed to be press-fitted to the inner peripheral edge portion
543 so as to form a sealing region. The seal member 56 has an engaging
recess 563 which confronts the anchoring portion 412 and which extends
in the longitudinal direction, and a third retaining groove 565
which is disposed in a front side of the engaging recess 563 and
which extends in a radial direction relative to the axis (X), as
shown in FIG. 5.
[0048] In use, the plunger 50 is pressed forwardly by a pushing
force applied to the end cap 57 to push the surrounding sealing
ring 59 to reach the rear surrounding edge portion 34 until the
injection limiting protrusion 545 abuts against the injection limiting
protrusion 25 to indicate the completion of the injection course.
In this state, the anchoring portion 412 is retained in the engaging
recess 563 by engagement of the third retaining protrusion 415 and
the third retaining groove 565 thereby resulting in securing the
needle seat 41 to the seal member 56.
[0049] Subsequently, with reference to FIGS. 5 and 6 when a pushing
force greater than the first and second frictional forces, i.e.
frictional forces generated between the first retaining protrusion
and groove 24350 and between the second retaining protrusion and
groove 414320 is further applied to the end cap 57 the tubular
barrier member 30 is pushed to move towards the surrounding shoulder
portion 222 to force the second retaining groove 320 to disengage
from the second retaining protrusion 414 so that the anchoring
portion 412 which remains fixedly in place due to abutment of the
surrounding front end wall 411 against the surrounding abutment
wall 213 is exposed to and is impacted by an impact force from
the seal member 56 along the axis (X) that the sealing line 566
is ruptured. Thus, the seal member 56 is released from the plunger
body 54 and the needle seat 41 and the needle cannula 42 together
with the seal member 56 are suctioned into the cavity 500 by a
suction force resulting from a pressure difference between the ambient
atmosphere and the reduced pressure in the cavity 500 as shown
in FIG. 7. Note that the seal member 56 has an outer surrounding
seal surface 564 which is configured to be kept in slidable contact
and air-tight engagement with the inner peripheral edge portion
543 when the seal member 56 is suctioned in the front cavity segment
51. Moreover, by virtue of the shoulder portion 55 and the barrier
ribs 58 the assembly of the needle seat 41 the needle cannula
42 and the seal member 56 can be trapped in the cavity 500.
[0050] In addition, as shown in FIG. 8 the inner surrounding barrel
wall surface of the barrel 20 is spaced apart from the needle cannula
42 in radial directions at the forward opening 231 to define a surrounding
clearance therebetween. In particular, a plurality of ribs 237 are
disposed on the inner surrounding barrel wall surface and are angularly
displaced from one another. Each rib 237 extends toward the needle
cannula 42 while forming an air duct 236 between two adjacent ones
of the ribs 237 to communicate the passage of the barrel 20 with
the ambient atmosphere. As such, the air ducts 236 can facilitate
inflow of the ambient air into the cavity 500.
[0051] Referring to FIGS. 9 and 10 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 biasing member 60
such as a compression spring, which is disposed in the front surrounding
region 211 to bias the needle seat 41 toward the seal member 56.
The biasing member 60 has two ends 6162 abutting against the inner
surrounding barrel wall surface at the forward opening 231 and the
surrounding front end wall 411 respectively, so as to increase
the impact force to facilitate retraction action of the suctioned
assembly into the cavity 500.
[0052] Referring to FIGS. 11 12 and 13 the third preferred embodiment
of the disposable syringe according to this invention is shown to
be similar to the first preferred embodiment in construction. In
this embodiment, the surrounding front end wall 411 includes a sealing
member 70 which abuts against the surrounding abutment wall 213
and which is in air-tight engagement with the rear surrounding region
212 so as to maintain air-tightness of the compressible chamber
26. The sealing member 70 includes an elastomeric plate 71 and an
elastomeric ring 72 which abut against each other and which have
axial holes 711721 that extend along the axis (X) to engage fittingly
the needle cannula 42 therein. In addition, the inner barrier wall
surface 31 of the tubular barrier member 30 further extends from
the front surrounding edge portion 33 to have a deformable sealing
portion 381 which is in air-tight engagement with the hub portion
410 of the tubular needle seat 41.
[0053] The compressible chamber 26 is filled with fluid. The hub
portion 410 of the tubular needle seat 41 has a plurality of through
holes 416 which are formed therethrough to be in fluid communication
with the compressible chamber 26 and which extend in the longitudinal
direction. As such, when the tubular barrier member 30 is moved
towards the surrounding shoulder portion 222 the fluid is compressed
to flow into the through holes 416 thereby helping force the anchoring
portion 412 to move toward the seal member 56 so as to increase
the impact force.
[0054] Referring to FIGS. 14 and 15 the fourth preferred embodiment
of the disposable syringe according to this invention is shown to
be similar to the third preferred embodiment in construction, and
further includes a biasing member 60 similar to that of the second
preferred embodiment to bias the needle seat 41 toward the seal
member 56. The biasing member 60 has two ends 6162 abutting against
the inner surrounding barrel wall surface at the forward opening
231 and the elastomeric plate 71 of the sealing member 70 respectively,
so as to increase the impact force to facilitate retraction action
of the suctioned assembly into the cavity 500.
[0055] Referring to FIGS. 16 17 18 and 19 the fifth, sixth,
seventh and eighth preferred embodiments of the disposable syringe
according to this invention are shown to be respectively similar
to the first, second, third and fourth preferred embodiment in construction,
but are used for an extremely small injection volume, such as 1
ml. Thus, the barrel 20 the tubular barrier member 30 the needle
assembly 40 the plunger 50 and the biasing member 60 are comparatively
smaller. In addition, in stead of a separate surrounding sealing
ring 59 the surrounding sealing ring in these embodiments includes
a plurality of ring portions 5441 which are formed integrally with
the outer peripheral wall surface 544 adjacent to the top end wall
541 for slidable and air-tight engagement with the larger-diameter
segment 22. Therefore, the annular anchoring protrusion 546 and
the annular retaining flange 547 (see FIG. 3) may be eliminated.
[0056] As shown in FIG. 20 the ninth preferred embodiment of the
disposable syringe according to this invention is shown to be similar
to the fifth preferred embodiment in construction. In this embodiment,
the tubular barrier member 30 further includes an annular flange
341 which extends from the rear surrounding edge portion 34 and
which is configured to be inserted into a clearance between the
top end wall 541 of the plunger body 54 and the rear surrounding
edge portion 34 thereby preventing trapping of medicine within
the clearance.
[0057] As illustrated, the disposable syringe of this invention
has the following advantages:
[0058] 1. The suction of the tubular needle seat 41 and the needle
cannula 42 occurs after the top end wall 541 the surrounding sealing
ring 59 the seal member 56 and the tubular barrier member 30 are
in tight contact with the tubular needle seat 41. Thus, the clearance
may not exist therebetween to minimize trapping of medicine or blood
within the barrel 20 after use.
[0059] 2. By virtue of the first and second frictional forces and
the abutment of the surrounding front end wall 411 against the surrounding
abutment wall 213 the tubular needle seat 41 can be retained firmly
in the retaining area during use. In addition, once the tubular
needle seat 41 is released from the tubular barrier member 30 by
a pushing force applied to the tubular barrier member 30 the tubular
needle seat 41 can be suctioned smoothly and easily into the cavity
500.
[0060] 3. After use, the needle seat 41 and the needle cannula
42 can be retracted into the cavity 500 of the plunger body 54 without
the application of a pulling force to the plunger 50. Thus, the
plunger body 54 can remain in the rear passageway 221 of the barrel
20 thereby facilitating the disposal of the disposable syringe.
[0061] 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. |