Abstrict A disposable syringe includes a plunger movable in a barrel relative
to a needle seat that engages an inner surrounding barrel wall surface
of the barrel by a resisting force. The plunger includes a plunger
body and a coupling rod which is in frictional engagement with the
plunger body and which has a central anchored area disposed to engage
an anchoring portion of the needle seat by a holding force. As such,
when the plunger body is moved to bring the central anchored area
into engagement with the anchoring portion, the resisting force
is overcome to permit disengagement of the needle seat from the
barrel, and the coupling rod and the needle seat can be retracted
into the plunger body by virtue of a biasing action of a biasing
member.
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 open lower
and upper ends 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 open lower and upper ends,
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, said larger-diameter segment including proximate
and distal surrounding regions which are opposite to each other
in the longitudinal direction and which are respectively proximate
to and distal from said surrounding shoulder portion; a tubular
needle seat including a hub portion disposed to fix said needle
cannula therein, and having a surrounding front end wall extending
radially relative to the axis, a surrounding gripped portion extending
from said hub portion in the longitudinal direction and away from
said surrounding front end wall, and an anchoring portion extending
from said surrounding gripped portion in the longitudinal direction
and away from said hub portion; a grip member disposed to bring
said surrounding gripped portion into engagement with one of said
rear surrounding region and said proximate surrounding region, said
grip member being configured to provide a resisting force that holds
said surrounding gripped portion in position so as to prevent movement
of said surrounding gripped portion relative to a respective one
of said rear surrounding region and said proximate surrounding region
during a piercing action of said needle cannula for a hypodermic
or intravenous injection, and that permits disengagement of said
surrounding gripped portion from said respective one of said rear
surrounding region and said proximate surrounding region so as to
enable a subsequent movement of said tubular needle seat relative
to said inner surrounding barrel wall surface when said grip member
is subjected to a first external force; a plunger which, in a position
of use, is disposed to be movable in said larger-diameter segment,
said plunger including a plunger body which includes a top end wall
movable towards said anchoring portion, a bottom end wall opposite
to said top end wall in the longitudinal direction, and extending
outwardly of said open lower end so as to be manually operable,
and a tubular intermediate wall that is interposed between said
top and bottom end walls, and that confines an accommodation chamber,
said top end wall having an inner peripheral edge portion that surrounds
the axis, and that defines an access opening therein, which is communicated
with said accommodation chamber, and a coupling rod including an
upper coupling end which is inserted in said access opening, and
which has a central anchored area that is engageable with said anchoring
portion by a holding force such that the engagement of said central
anchored area with said anchoring portion is not disrupted during
the disengagement of said surrounding gripped portion from said
respective one of said rear surrounding region and said proximate
surrounding region, and a surrounding abutment area that surrounds
said central anchored area, and that is disposed to be in frictional
engagement with said inner peripheral edge portion, such that when
said upper coupling end is depressed towards said bottom end wall
by virtue of movement of said tubular needle seat relative to said
upper coupling end, said coupling rod is disengaged from said inner
peripheral edge portion so as to enable said coupling rod to be
forced from the position of use to a retracted position where said
coupling rod is disposed closer to said bottom end wall, and a shank
portion extending from said upper coupling end towards said bottom
end wall and terminating at a thrust end; a biasing member disposed
between said shank portion and said tubular intermediate wall to
bias said coupling rod towards the retracted position; a retaining
member disposed to retain said thrust end in the position of use
against biasing action of said biasing member; and a triggering
member disposed to prevent said retaining member from retaining
said thrust end in response to a second external force, thereby
permitting said coupling rod to be biased towards the retracted
position.
2. The disposable syringe according to claim 1 wherein said tubular
intermediate wall has outer and inner tubular wall surfaces opposite
to each other in radial directions relative to the axis, said retaining
member having a retaining groove which is formed in said inner tubular
wall surface, which extends radially and towards said outer tubular
wall surface, and which is displaced from said top end wall, said
biasing member being a coiled spring that surrounds said shank portion,
said coiled spring having an upper end engaging said top end wall,
and a lower end that is opposite to said upper end, said lower end
being inserted into and being retained in said retaining groove
against the biasing action, said triggering member including an
actuated portion which has a pushed end coupled to and moved with
said thrust end, and a pulling end disposed to pull said lower end
out of said retaining groove once said pushed end is moved downwardly
with said thrust end when said upper coupling end is depressed to
be disengaged from said inner peripheral edge, thereby enabling
said coupling rod to be forced by virtue of the biasing action to
move to the retracted position.
3. The disposable syringe according to claim 1 wherein said biasing
member is a coiled spring that surrounds said shank portion, said
coiled spring having an upper end engaging said top end wall, and
a lower end that is opposite to said upper end, said thrust end
having an enlarged end edge which, in cooperation with said shank
portion, forms an abutment shoulder for engaging said lower end
of said coiled spring, said tubular intermediate wall having outer
and inner tubular wall surfaces opposite to each other in radial
directions relative to the axis, said outer tubular wall surface
having an access hole which extends radially through said inner
tubular wall surface, said retaining member having a locking pin
which is received in said access hole and which is radially movable
between a locking position where said locking pin abuts said enlarged
end edge against the biasing action, and a releasing position where
said locking pin is retracted to release said enlarged end edge
so that said coupling rod is forced by virtue of the biasing action
to move to the retracted position, said triggering member being
pivotally mounted on said outer tubular wall surface at a fulcrum
point, and including a weight end formed integrally with said locking
pin, and a power end disposed at an opposite side of said weight
end relative to said fulcrum point so as to be actuated to move
said locking pin to the releasing position.
4. The disposable syringe according to claim 1 wherein said proximate
surrounding region is formed with a retaining protrusion, said grip
member including an outer grip wall surface which is configured
to engage retainingly said retaining protrusion with a first frictional
force and which is in water-tight engagement with said proximate
surrounding region, and an inner grip wall surface which is opposite
to said outer grip wall surface in radials direction relative to
the axis and which engages retainingly said surrounding gripped
portion with a second frictional force that, together with the first
frictional force, serves as the resisting force.
5. The disposable syringe according to claim 4 wherein said smaller-diameter
segment has a shoulder disposed between said front and rear surrounding
regions to block forward movement of said surrounding front end
wall so as to permit disengagement of said surrounding grip portion
from said inner grip wall surface and from said proximate surrounding
region when said top end wall is moved to push said grip member
towards said surrounding shoulder portion by the first external
force that is greater than the resisting force, thereby enabling
the engagement of said central anchored area with said anchoring
portion.
6. The disposable syringe according to claim 5 wherein said central
anchored area has an embossed pin which extends toward said anchoring
portion so as for insertion thereinto and for retention therein,
thereby providing the holding force.
7. The disposable syringe according to claim 4 further comprising
a sealing member which is in air-tight engagement with said rear
surrounding region so as to cooperate with said grip member to confine
a compressible chamber in said proximate surrounding region, said
compressible chamber being filled with a fluid, said hub portion
of said needle seat having a through hole which is formed therethrough
to be in fluid communication with said compressible chamber such
that when said grip member is moved towards said surrounding shoulder
portion, said fluid is forced to flow into said through hole to
assist in depression of said upper coupling end towards said bottom
end wall, thereby speeding up movement of said coupling rod to the
retracted position.
8. The disposable syringe according to claim 4 further comprising
a first male screw thread segment and a first female screw thread
segment which are respectively disposed on said outer tubular wall
surface and said distal surrounding region for providing the second
external force by virtue of screw-in engagement of said first male
screw thread segment with said first female screw thread segment.
9. The disposable syringe according to claim 1 wherein said grip
member includes a second female screw thread segment which is disposed
on said rear surrounding region, and a second male screw thread
segment which is disposed on said surrounding gripped portion, said
second male screw thread segment threadedly engaging said second
female screw thread segment such that the resisting force is provided
between said surrounding gripped portion and said rear surrounding
region, and such that screw-out movement of said second male screw
thread segment relative to said second female screw thread segment
results in disappearance of the resisting force so as to permit
disengagement of said surrounding gripped portion from said rear
surrounding region, said central anchored area having an engaging
recess which confronts said anchoring portion and which extends
in the longitudinal direction so as to engage said anchoring portion,
and a third female screw thread segment disposed in said engaging
recess; said anchoring portion having a third male screw thread
segment, rotation of said third male and female screw thread segments
relative to each other permitting engagement of said central anchored
area with said anchoring portion, thereby providing the holding
force.
10. The disposable syringe according to claim 1 further comprising
a catheter hub which defines a duct therein, and which includes
a sleeve portion that is sleeved on said barrel, and a tip portion
opposite to said sleeve portion along the axis, and a tubular catheter
which has a proximate segment that is disposed in said tip portion
and that extends along the axis to communicate fluidly with said
duct, and a distal segment that extends from said proximate segment
along the axis to project outwardly of said tip portion, said needle
cannula extending through said tubular catheter to terminate at
a tip end that projects outwardly of said distal segment of said
tubular catheter.
11. The disposable syringe according to claim 1 wherein said barrel
has an outer surrounding barrel wall surface which surrounds the
axis and which includes front and rear outer surrounding segments
that are disposed opposite to said smaller-diameter segment and
said larger-diameter segment in directions radial to the axis, respectively,
and a rib portion which is disposed on said front outer surrounding
segment and which extends in the longitudinal direction, said disposable
syringe further comprising a tip protector which is sleeved frictionally
on said rib portion so as for shielding said needle cannula.
12. The disposable syringe according to claim 11 wherein said
outer surrounding barrel wall surface further includes a transition
surrounding segment which is interposed between said front and rear
outer surrounding segments, and which diverges gradually from said
front outer surrounding segment to said rear outer surrounding segment
such that extension of said rib portion onto said transition surrounding
segment ensures a firm engagement between said tip protector and
said rib portion when said tip protector is brought to be sleeved
thereonto.
13. The disposable syringe according to claim 1 wherein said triggering
member is an enlarged end edge which extends from said thrust end
of said coupling rod, and which, in cooperation with said shank
portion, forms an abutment shoulder for engaging said lower end
of said coiled spring, said retaining member having a retaining
groove which is formed in said inner tubular wall surface, and a
protrusion which is formed on and which extends radially from said
enlarged end edge so as to releasably engage said retaining groove.
14. The disposable syringe according to claim 1 wherein said accommodation
chamber includes front and rear chamber regions which are respectively
proximate to said top and bottom end walls, said rear chamber region
being of a dimension larger than that of said front chamber region
so as to clear the way for said biasing member when said biasing
member biases said coupling rod towards the retracted position.
Description CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority of Taiwanese Application
No. 092109392 filed on Apr. 22 2003.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to a disposable syringe, more particularly
to a disposable syringe which enables a needle cannula to be retracted
into a plunger body.
[0004] 2. Description of the Related Art
[0005] Referring to FIGS. 1 and 2 U.S. Pat. No. 5211628 discloses
a syringe with an automatic retracting needle, which includes a
barrel 11 with a chamber, a flexible lock member 12 fixed in the
chamber adjacent to a lower end 111 thereof, a flexible needle seat
13 positioned in the chamber adjacent to the lower end 111 and formed
with an opening 131 a needle cannula 14 fastened to the needle
seat 13 in the opening 131 and extending through an orifice 112
in the lower end 111 a plunger 15 slidable in the chamber along
an axis (X), a shaft 16 disposed in the plunger 15 and having an
integral annular lower foot part 161 which is press-fitted against
an upwardly extending lip 151 of the plunger 15 and a spring 17
surrounding the shaft 16 and having one end 172 which abuts against
an upper end 163 of the shaft 16 and the other end 171 which is
retained in a compressed state by engagement of the lip 151 with
the lower foot part 161. The lock member 12 has a flexible inwardly
protruding lip 121 which bears on a shoulder 134 of the needle seat
13 to prevent the needle seat 13 from moving upwardly.
[0006] The shaft 16 further includes a lower protrusion 162 shaped
to mate with the opening 131. As such, when the plunger 15 is pressed
downwardly along the axis (X), the lower protrusion 162 can be inserted
into the opening 131 and the lower foot part 161 spreads the lip
121 outwardly so that the lip 121 is bent to disengage from the
shoulder 134. At the same time, the residual force of the lip 121
against the lower foot part 161 causes a slight inward bend of the
lower foot part 161 and momentarily causes the lower foot part 161
to lose contact with the lip 151. The compressive force of the spring
17 then urges the upper end 163 of the shaft 16 upwardly. Due to
the mating fit of the lower protrusion 162 with the opening 131
the upward movement is also transferred to the needle seat 13 and
the needle cannula 14 which are urged upwardly into the plunger
15.
[0007] However, in order to ensure smooth retraction of the needle
seat 13 and the needle cannula 14 into the plunger 15 the engagement
of the lower foot part 161 with the lip 151 cannot be very tight.
However, a loose engagement may result in an undesired release of
the compressive force of the spring 17. Moreover, some medicine
may enter the plunger 15 from a clearance between the lower foot
part 161 and the lip 151. Furthermore, the lower foot part 161
which has a conical shape, may interfere with the retraction of
the shaft 16 into the plunger 15.
SUMMARY OF THE INVENTION
[0008] The object of the present invention is to provide a disposable
syringe which can be operated easily and smoothly to retract a used
needle into a plunger body.
[0009] According to this invention, the disposable syringe includes
a barrel which has an inner surrounding barrel wall surface surrounding
an axis and confining a passage. The passage has open lower and
upper ends 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 open lower and upper ends, respectively,
to form a surrounding shoulder portion therebetween. The smaller-diameter
segment includes a front surrounding region and a rear surrounding
region which is proximate to the surrounding shoulder portion. The
larger-diameter segment includes proximate and distal surrounding
regions respectively disposed proximate to and distal from the surrounding
shoulder portion.
[0010] A tubular needle seat includes a hub portion which is disposed
to fix a needle cannula therein, and which has a surrounding front
end wall extending radially relative to the axis, a surrounding
gripped portion extending from the hub portion, and an anchoring
portion extending from the surrounding gripped portion.
[0011] A grip member is disposed to bring the surrounding gripped
portion into engagement with one of the rear surrounding region
and the proximate surrounding region. The grip member can provide
a resisting force that holds the surrounding gripped portion in
position so as to prevent movement of the surrounding gripped portion
relative to a respective one of the rear surrounding region and
the proximate surrounding region during a piercing action of the
needle cannula for a hypodermic injection, and that permits disengagement
of the surrounding gripped portion from the respective one of the
rear surrounding region and the proximate surrounding region so
as to enable a subsequent movement of the tubular needle seat relative
to the inner surrounding barrel wall surface when the surrounding
gripped portion is subjected to a first external force.
[0012] A plunger, in a position of use, is disposed to be movable
in the larger-diameter segment, and includes a plunger body and
a coupling rod.
[0013] The plunger body includes a top end wall movable towards
the anchoring portion, a bottom end wall opposite to the top end
wall, and a tubular intermediate wall interposed between the top
and bottom end walls and confining an accommodation chamber. The
top end wall has an inner peripheral edge portion defining an access
opening therein, which is communicated with the accommodation chamber.
[0014] The coupling rod includes an upper coupling end which is
inserted in the access opening, and which has a central anchored
area that is engageable with the anchoring portion by a holding
force such that engagement of the central anchored area with the
anchoring portion is not disrupted during the disengagement of the
surrounding gripped portion from the respective one of the rear
surrounding region and the proximate surrounding region. The upper
coupling end further has a surrounding abutment area which surrounds
the central anchored area, and which is in frictional engagement
with the inner peripheral edge portion. As such, when the upper
coupling end is depressed towards the bottom end wall by virtue
of movement of the tubular needle seat relative to the upper coupling
end, the coupling rod is disengaged from the inner peripheral edge
portion so as to enable the coupling rod to be forced from the position
of use to a retracted position where the coupling rod is disposed
closer to the bottom end wall. The coupling rod further includes
a shank portion extending from the upper coupling end towards the
bottom end wall and terminating at a thrust end.
[0015] A biasing member is disposed between the shank portion and
the tubular intermediate wall to bias the coupling rod towards the
retracted position.
[0016] A retaining member is disposed to retain the thrust end
in the position of use against biasing action of the biasing member.
[0017] A triggering member is disposed to prevent the retaining
member from retaining the thrust end in response to a second external
force, thereby permitting the coupling rod to be biased towards
the retracted position.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] 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:
[0019] FIG. 1 is a sectional view of a conventional syringe;
[0020] FIG. 2 is a fragmentary sectional view of the conventional
syringe after use;
[0021] FIG. 3 is an exploded sectional view of the first preferred
embodiment of a disposable syringe according to this invention;
[0022] FIG. 4 is a sectional view of the first preferred embodiment
in a state of use;
[0023] FIGS. 5 to 7 are fragmentary sectional views of the first
preferred embodiment, showing a grip member in three different states;
[0024] FIG. 8 is a sectional view of the first preferred embodiment
in a retracted state;
[0025] FIG. 9 is a sectional view of the first preferred embodiment
in another retracted state;
[0026] FIG. 10 is a sectional view of the second preferred embodiment
of a disposable syringe according to this invention;
[0027] FIG. 11 is a sectional view of the second preferred embodiment,
showing a tubular needle seat in a disengaging state;
[0028] FIG. 12 is a sectional view of the third preferred embodiment
of a disposable syringe according to this invention;
[0029] FIG. 13 is a sectional view of the third preferred embodiment
in a retracted state;
[0030] FIG. 14 is a sectional view of the fourth preferred embodiment
of a disposable syringe according to this invention;
[0031] FIG. 15 is a fragmentary sectional view showing an alternative
configuration of a tubular needle seat and a coupling rod of the
fourth preferred embodiment;
[0032] FIG. 16 is a sectional view of the fourth preferred embodiment
in a retracted state;
[0033] FIG. 17 is a sectional view of the fifth preferred embodiment
of a disposable syringe according to this invention;
[0034] FIG. 18 is an exploded sectional view of the fifth preferred
embodiment in a retracted state;
[0035] FIG. 19 is a fragmentary sectional view of the sixth preferred
embodiment of a disposable syringe according to this invention;
[0036] FIG. 20 is a sectional view of the seventh preferred embodiment
of a disposable syringe according to this invention;
[0037] FIGS. 21 and 22 are fragmentary sectional views showing
a grip member of the seventh preferred embodiment in two different
states;
[0038] FIG. 23 is a sectional view of the seventh preferred embodiment
in a retracted state;
[0039] FIG. 24 is a side view of the eighth preferred embodiment
of a disposable syringe according to this invention;
[0040] FIG. 25 is a partly sectional view of the eighth preferred
embodiment;
[0041] FIG. 26 is a partly sectional view of the eighth preferred
embodiment in a retracted state; and
[0042] FIG. 27 is an exploded, partly sectional view of the ninth
preferred embodiment of a disposable syringe according to this invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0043] 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.
[0044] Referring to FIGS. 3 and 4 the first preferred embodiment
of a disposable syringe according to the present invention is shown
to comprise a barrel 2 a needle assembly 4 including a needle cannula
42 a tubular needle seat 41 and a tip protector 43 a grip member
3 a plunger, a biasing member 7 a retaining member 8 and a triggering
member.
[0045] The barrel 2 has an inner surrounding barrel wall surface
230 which surrounds an axis (X) and which confines a passage. The
passage has an open lower end 232 and an open upper end 231 which
are disposed opposite to each other in a longitudinal direction
parallel to the axis (X). The inner surrounding barrel wall surface
230 includes a larger-diameter segment 22 and a smaller-diameter
segment 21 which confine rear and front passageways, respectively,
and which are disposed proximate to the open lower end 232 and the
open upper end 231 respectively, to form a surrounding shoulder
portion 26 therebetween. The smaller-diameter segment 21 includes
a front surrounding region 233 a rear surrounding region 234 which
is proximate to the surrounding shoulder portion 26 and a shoulder
235 which is disposed between the front and rear surrounding regions
233234. The larger-diameter segment 22 includes proximate and distal
surrounding regions 221222 which are opposite to each other in
the longitudinal direction and which are respectively proximate
to and distal from the surrounding shoulder portion 26. The proximate
and distal surrounding regions 221222 are formed with retaining
protrusions 238239 respectively. The barrel 2 further has an outer
surrounding barrel wall surface 29 which surrounds the axis (X),
and which includes front and rear outer surrounding segments 291292
that are disposed opposite to the smaller-diameter segment 21 and
the larger-diameter segment 22 in directions radial to the axis
(X), respectively, and a transition surrounding segment 293 which
is interposed between the front and rear outer surrounding segments
291292 and which diverges gradually from the front outer surrounding
segment 291 to the rear outer surrounding segment 292. A rib portion
236 is disposed on the front outer surrounding segment 291 and
extends in the longitudinal direction to the transition surrounding
segment 293.
[0046] The needle seat 41 includes a hub portion 416 which is disposed
to fix the needle cannula 42 therein, and which has a surrounding
front end wall 411 extending radially relative to the axis (X),
a surrounding gripped portion 417 which extends from the hub portion
416 in the longitudinal direction and away from the surrounding
front end wall 411 and an anchoring portion 412 which extends from
the surrounding gripped portion 417 in the longitudinal direction
and away from the hub portion 416. The surrounding front end wall
411 is disposed to abut against the shoulder 235 so as to block
forward movement of the needle seat 41. The needle cannula 42 extends
through the open upper end 231. The tip protector 43 is sleeved
frictionally on the rib portion 236 for shielding the needle cannula
42. Note that the extension of the rib portion 236 onto the transition
surrounding segment 293 ensures the firm engagement between the
tip protector 43 and the rib portion 236.
[0047] With reference to FIG. 5 a grip member 3 includes an outer
grip wall surface 32 which engages retainingly the retaining protrusion
238 with a first frictional force and which is in water-tight engagement
with the proximate surrounding region 221 and an inner grip wall
surface 31 which is opposite to the outer grip wall surface 32 in
radial directions relative to the axis (X) and which engages retainingly
the surrounding gripped portion 417 of the needle seat 41 with a
second frictional force that, together with the first frictional
force, provides a resisting force. Thus, the surrounding gripped
portion 417 of the needle seat 41 is brought into engagement with
the proximate surrounding region 221 through the grip member 3.
The resisting force (i.e. the first and second frictional forces)
can hold the surrounding gripped portion 417 in position so as to
prevent movement of the surrounding gripped portion 417 relative
to the proximate surrounding region 221 during a piercing action
of the needle cannula 42 for a hypodermic injection, and can permit
disengagement of the surrounding gripped portion 417 from the proximate
surrounding region 221 to enable a subsequent movement of the needle
seat 41 relative to the inner surrounding barrel wall surface 230
when the surrounding gripped portion 417 is subjected to a first
external force.
[0048] The plunger includes a plunger body 5 and a coupling rod
6 and is disposed to be movable in the larger-diameter segment
22 in a position of use.
[0049] The plunger body 5 includes a top end wall 543 which is
disposed to be movable towards the anchoring portion 412 a bottom
end wall 544 which is opposite to the top end wall 543 in the longitudinal
direction, and which extends outwardly of the open lower end 232
so as to be manually operable, and a tubular intermediate wall 54
which is interposed between the top and bottom end walls 543544
and which confines an accommodation chamber 51. The accommodation
chamber 51 includes front and rear chamber regions 511512 which
are respectively proximate to the top and bottom end walls 543544
and the rear chamber region 512 has an inner diameter larger than
that of the front chamber region 511. The top end wall 543 has an
inner peripheral edge portion 545 which surrounds the axis (X),
and which defines an access opening 53 therein to be communicated
with the accommodation chamber 51. A deformable surrounding ring
56 is sleeved retainingly on the top end wall 543. The tubular intermediate
wall 54 has outer and inner tubular wall surfaces 546541 opposite
to each other in radial directions relative to the axis (X). An
end cap 55 is disposed to cover the bottom end wall 544.
[0050] The coupling rod 6 includes an upper coupling end 61 and
a shank portion 67. The upper coupling end 61 is inserted in the
access opening 53 and has a central anchored area 63 which has
an engaging recess that confronts the anchoring portion 412 and
that extends in the longitudinal direction so as to be engageable
with the anchoring portion 412. In this embodiment, the engaging
recess and the anchoring portion 412 are shaped to mate with each
other with a holding force such that the engagement of the central
anchored area 63 with the anchoring portion 412 is not disrupted
during the disengagement of the surrounding gripped portion 417
from the proximate surrounding region 221. The upper coupling end
61 further has a surrounding abutment area 66 which surrounds the
central anchored area 63 and which is disposed to be in frictional
engagement with the inner peripheral edge portion 545. As such,
when the upper coupling end 61 is depressed towards the bottom end
wall 544 by virtue of movement of the needle seat 41 relative to
the upper coupling end 61 the coupling rod 6 is disengaged from
the inner peripheral edge portion 545 so as to enable the coupling
rod 6 to be forced from the position of use to a retracted position
where the coupling rod 6 is disposed closer to the bottom end wall
544. The shank portion 67 extends from the upper coupling end 61
towards the bottom end wall 544 and terminates at a thrust end
62.
[0051] The retaining member 8 includes a spiral retaining groove
81 which is formed in the inner tubular wall surface 541 at the
front chamber region 511 which extends radially towards the outer
tubular wall surface 546 and which is displaced from the top end
wall 543 and a positioning groove 82 which is formed in the thrust
end 62.
[0052] The biasing member 7 is a coiled spring 7 that surrounds
the shank portion 67. The coiled spring 7 has an upper end 71 which
abuts against a step portion 542 of the top end wall 543 and a
lower end 72 opposite to the upper end 71 and having a diameter
substantially larger than that of the upper end 71. The lower end
72 is inserted into and is retained in the retaining groove 81 against
a biasing action of the coiled spring 7 so as to retain the thrust
end 62 in the position of use against the biasing action.
[0053] In this embodiment, the triggering member includes an actuated
portion which is formed integrally with the coiled spring 7. The
actuated portion has a pushed end 83 which is inserted into the
positioning groove 82 to be moved with the thrust end 62 and a
pulling end 89 which is disposed to pull the lower end 72 out of
the retaining groove 81 once the pushed end 83 is moved downwardly
with the thrust end 62 when the upper coupling end 61 is depressed
to be disengaged from the inner peripheral edge 545 in response
to a second external force, thereby enabling the coupling rod 6
to be forced by virtue of the biasing action of the coiled spring
7 to move to the retracted position.
[0054] In use, the plunger body 5 is pressed forwardly to push
the surrounding ring 56 against the grip member 3 to complete an
injection course. In this state, a part of the anchoring portion
412 is inserted into the engaging recess of the central anchored
area 63 as shown in FIG. 5.
[0055] Subsequently, referring to FIG. 6 when a pushing force,
i.e. the aforesaid first external force, which is greater than the
resisting force, is further applied to the plunger body 5 the top
end wall 543 and the surrounding ring 56 are moved to push the grip
member 3 towards the surrounding shoulder portion 26 relative to
the surrounding grip portion 417 due to the abutment of the surrounding
front end wall 411 against the shoulder 235. The surrounding grip
portion 417 is then disengaged from the inner grip wall surface
31 and from the proximate surrounding region 221 thereby enabling
the anchoring portion 412 to engage the engaging recess of the central
anchored area 63.
[0056] Referring to FIGS. 7 and 8 when another force, i.e. the
second external force, is applied to press the plunger body 5 to
push the grip member 3 to the surrounding shoulder portion 26 the
coupling rod 6 is prevented from movement due to the engagement
of the central anchored area 63 with the anchoring portion 412
and the inner peripheral edge portion 545 is moved relative to the
surrounding abutment area 66 such that the lower end 72 of the coiled
spring 7 is brought to disengage from the retaining groove 81 thereby
enabling the coupling rod 6 to be forced by virtue of the biasing
action of the coiled spring 7 to move to the retracted position.
At the same time, by engagement of the central anchored area 63
with the anchoring portion 412 the needle seat 41 and the needle
cannula 42 can be retracted into the accommodation chamber 51 and
can be retained in the accommodation chamber 51 by the end cap 55.
Note that due to the dimension of the rear chamber segment 512 is
larger than that of the front chamber segment 511 the way for the
biasing member 7 is cleared when the biasing member 7 biases the
coupling rod 6 towards the retracting position.
[0057] Alternatively, referring to FIG. 9 the plunger body 5 may
be pulled rearward after the engagement of the central anchored
area 63 with the anchoring portion 412 so that the needle seat 41
and the needle cannula 42 can be retracted into the passage of the
barrel 2 without using the biasing action of the coiled spring 7.
[0058] Referring to FIGS. 10 and 11 the second preferred embodiment
of a disposable syringe according to this invention is shown to
be similar to the first preferred embodiment in construction. The
differences reside in that the thrust end 62 of the coupling rod
6 has an enlarged end edge 84 which, in cooperation with the shank
portion 67 forms an abutment shoulder 621 for engaging the lower
end 72 of the coiled spring 7. The retaining member 8 further has
a spirally surrounding protrusion 85 which is formed on and which
extends radially from the enlarged end edge 84 so as to releasably
engage the retaining groove 81 in the inner tubular wall surface
541 of the plunger body 5.
[0059] As such, when the anchoring portion 412 is pressed to move
the upper coupling end 61 relative to the inner peripheral edge
portion 545 by virtue of the second external force, the surrounding
protrusion 85 is moved to disengage from the retaining groove 81
so as to permit retraction of the coupling rod 6 the needle seat
41 and the needle cannula 42 into the accommodation chamber 51.
[0060] Referring to FIGS. 12 and 13 the third preferred embodiment
of a disposable syringe according to this invention is shown to
be similar to the first preferred embodiment in construction, and
further includes a sealing member 44 which is in air-tight engagement
with the rear surrounding region 234 so as to cooperate with the
grip member 3 to confine a compressible chamber 443 in the proximate
surrounding region 221. The compressible chamber 443 is filled with
a fluid. The sealing member 44 includes an elastomeric plate 441
and an elastomeric ring 442 which abut against each other. In addition,
the hub portion 416 of the needle seat 41 has a through hole 413
which is formed therethrough and which is in fluid communication
with the compressible chamber 443 such that when the grip member
3 is moved towards the surrounding shoulder portion 26 the fluid
is forced to flow into the through hole 413 to assist in depression
of the upper coupling end 61 of the coupling rod 6 as well as the
needle seat 41 and the needle cannula 42 towards the bottom end
wall 544 thereby speeding up the movement of the coupling rod 6
to the retracted position.
[0061] Referring to FIGS. 14 and 16 the fourth preferred embodiment
of a disposable syringe according to this invention is adapted for
injecting medication of a very small volume, such as 1 ml. Thus,
the barrel 2 the grip member 3 the needle seat 41 the plunger
body 5 the coupling rod 6 the biasing member 7 and the retaining
member 8 are comparatively smaller in size. In addition, an embossed
pin 65 extends from the pushed end 83 forwardly, projects forwardly
of the central anchored area 63 of the coupling rod 6 and is formed
with screw threads thereon. The embossed pin 65 extends toward the
anchoring portion 412 of the needle seat 41 for insertion thereinto
and for retention therein, thereby providing the holding force.
[0062] Alternatively, referring to FIG. 15 the embossed pin 65
is also formed on and extends from the central anchored area 63
of the coupling rod 6.
[0063] Furthermore, a needle mount 45 is provided to sleeve on
and to secure the needle cannula 42 and the hub portion 416 of the
needle seat 41. An assembly of the needle mount 45 the needle cannula
42 and the needle seat 41 is inserted into the barrel 2. Thus, mounting
of the needle cannula 42 and the needle seat 41 to the barrel 2
can be conducted easily, and the smaller-diameter segment 21 of
the barrel 2 can have a relatively large diameter so as to facilitate
fabrication.
[0064] Referring to FIGS. 17 and 18 the fifth preferred embodiment
of a disposable syringe according to this invention is shown to
be similar to the first preferred embodiment in construction, and
further includes an intravenous catheter device 9 which includes
a catheter hub 91 and a tubular catheter 92. The catheter hub 91
defines a duct therein, and includes a sleeve portion that is sleeved
on the outer surrounding barrel wall surface 29 of the barrel 2
adjacent to the open upper end 231 and a tip portion opposite to
the sleeve portion along the axis. The tubular catheter 92 has a
proximate segment which is disposed in the tip portion of the catheter
hub 91 and which extends along the axis to communicate fluidly with
the duct, and a distal segment that extends from the proximate segment
along the axis to project outwardly of the tip portion. The needle
cannula 42 extends through the tubular catheter 92 to terminate
at a tip end 421 that projects outwardly of the distal segment of
the tubular catheter 92.
[0065] In use, when the tip end 421 and the distal segment of the
tubular catheter 92 are inserted into a patient's vein, the user
can pull the plunger body 5 slightly rearward to draw blood so as
to confirm correct insertion of the tubular catheter 92 into the
patient's vein. After the needle cannula 42 is removed from the
tubular catheter 92 the needle seat 41 and the needle cannula 42
are retracted into the plunger body 5 in the same manner as described
above.
[0066] Referring to FIG. 19 the sixth preferred embodiment of
a disposable syringe according to this invention is shown to be
similar to the fifth preferred embodiment in construction, and further
includes a first male screw thread segment 547 and a first female
screw thread segment 24 which are respectively disposed on the outer
tubular wall surface 546 of the plunger body 5 and the distal surrounding
region 222 of larger-diameter segment 22 of the barrel 2. When the
first male screw thread segment 547 is in a screw-in engagement
with the first female screw thread segment 24 to provide the second
external force, the plunger body 5 can be moved more easily to push
the grip member 3 to the surrounding shoulder portion 26.
[0067] Referring to FIG. 20 the seventh preferred embodiment of
a disposable syringe according to this invention is shown to be
similar to the sixth preferred embodiment in construction. The differences
reside in that the grip member includes a second female screw thread
segment 25 which is disposed on the rear surrounding region 234
of the smaller-diameter segment 21 of the barrel 2 and a second
male screw thread segment 415 which is disposed on the surrounding
gripped portion 417 of the needle seat 41. The second male screw
thread segment 415 is in a threaded engagement with the second female
screw thread segment 25 such that the resisting force is provided
between the surrounding gripped portion 417 and the rear surrounding
region 234 and such that screw-out movement of the second male
screw thread segment 415 relative to the second female screw thread
segment 25 results in disappearance of the resisting force to permit
disengagement of the surrounding gripped portion 417 from the rear
surrounding region 234.
[0068] In addition, the central anchored area 63 has a third female
screw thread segment 68 which is disposed in the engaging recess
thereof. The anchoring portion 412 has a third male screw thread
segment 414. The anchoring portion 412 is brought into engagement
with the central anchored area 63 by virtue of rotation of the third
male screw thread segment 414 and the third female screw thread
segment 68 relative to each other, thereby providing the holding
force.
[0069] As such, referring to FIGS. 20 to 22 when the plunger body
5 is rotated by virtue of the screw-in engagement of the first male
screw thread segment 547 and the first female screw thread segment
24 the third female screw thread segment 68 is permitted to engage
the third male screw thread segment 414 and the second male screw
thread segment 415 is permitted to disengage from the second female
screw thread segment 25 such that the coupling rod 6 is pressed
as described above to permit retraction of the needle seat 41 and
the needle cannula 42 into the plunger body 5. Referring to FIGS.
24 and 25 the eighth preferred embodiment of a disposable syringe
according to this invention is shown to be similar to the seventh
preferred embodiment in construction. The differences reside in
that the thrust end 62 of the coupling rod 6 has an enlarged end
edge 84 which, in cooperation with the shank portion 67 forms an
abutment shoulder 621 for engaging the lower end 72 of the coiled
spring 7. The outer tubular wall surface 546 of the tubular intermediate
wall 54 of the plunger body 5 has an access hole 86 which extends
radially through the inner tubular wall surface 541.
[0070] In addition, the retaining member 8 has a locking pin 872
which is received in the access hole 86 and which is movable radially
between a locking position (see FIG. 25), where the locking pin
872 extends into the accommodation chamber 51 to abut the enlarged
end edge 84 against the biasing action of the coiled spring 7 and
a releasing position (see FIG. 26), where the locking pin 872 is
retracted to release the enlarged end edge 84 so that the coupling
rod 6 is forced by virtue of the biasing action of the coiled spring
7 to move to the retracted position.
[0071] Furthermore, the triggering member is formed as a lever
87 and is mounted pivotally on the outer tubular wall surface 546
at a fulcrum point 871 by means of a C-shaped clip 88 which is sleeved
on the outer tubular wall surface 546 and which has an end 881 passing
through the fulcrum point 871. The lever 87 includes a weight end
874 which is formed integrally with the locking pin 872 and a power
end 873 which is disposed at the opposite side of the weight end
874 relative to the fulcrum point 871 so as to be actuated to move
the locking pin 872 to the releasing position.
[0072] Referring to FIG. 27 alternatively, in the ninth preferred
embodiment, the tubular intermediate wall 54 of the plunger body
5 has two access holes 86 the retaining member 8 has two locking
pins 872 and the triggering member has two levers 87 which are
mounted pivotally on the tubular intermediate wall 54 by means of
a C-shaped clip 88. Pressing of the power ends 873 of the levers
87 can result in retraction of the locking pins 872 to permit retracting
movement of the coupling rod 6 by virtue of the biasing action of
the coiled spring 7.
[0073] As illustrated, the disposable syringe of this invention
has the following advantages:
[0074] 1. After completion of the injection course, the first and
second external forces are applied to push the plunger body 5 forward
to permit disengagement of the surrounding gripped portion 417 of
the needle seat 41 from a respective one of the rear surrounding
region 234 and the proximate surrounding region 221 to permit engagement
of the anchoring portion 412 with the central anchored area 63
and to permit retraction of the needle seat 41 and the needle cannula
42 into the plunger body 5 thereby rendering the disposal of the
syringe safe and convenient.
[0075] 2. Since the coupling rod 6 is in air-tight engagement with
the inner peripheral edge portion 545 of the plunger body 5 entry
of medication fluid into the plunger body 5 can be prevented. In
addition, the disposable syringe has a simple construction that
is easy to fabricate and assemble at a relatively low cost.
[0076] 3. The disposable syringe can serve as an intravenous catheter
inserting device for insertion of the tubular catheter 92 into a
patient's vein for administrating medication fluid into the patient's
vein or for drawing blood.
[0077] 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. |