Abstrict A disposable syringe has a needle seat with an upper segment adapted
to be fitted with a needle cannula, and a lower segment retained
in a passage of a barrel. A plunger has a stem portion movable in
the passage, a deformable surrounding engaging portion in sealing
contact with the passage so as to be moved by the stem portion to
a position of use, and a surrounding abutting head which is moved
towards and which is held by a grip segment in the needle seat when
the surrounding engaging portion is depressed by an edge portion
of the needle seat by virtue of a continuing depression force of
the plunger, thereby permitting the needle seat to be brought into
the passage for disposal.
Claims We claim:
1. A disposable syringe adapted to be used with a needle cannula,
comprising: a barrel having an inner surrounding barrel wall surface
which surrounds an axis and which confines a passage, said passage
having lower and upper open ends which are disposed opposite to
each other in a longitudinal direction that is parallel to the axis,
said inner surrounding barrel wall surface including a larger-diameter
segment and a smaller-diameter segment which are disposed proximate
to said lower and upper open ends, respectively, and which cooperatively
form a first surrounding shoulder portion therebetween; a tubular
needle seat disposed to be insertable into said passage from said
lower open end toward said upper open end, said needle seat including
a lower surrounding edge portion which is disposed to abut against
said first surrounding shoulder portion, an upper surrounding edge
portion disposed opposite to said lower surrounding edge portion
in the longitudinal direction, and a surrounding seat wall interposed
between said lower and upper surrounding edge portions, and having
an inner tubular wall surface which surrounds the axis to confine
a duct, which has a grip segment, and which is adapted to be fitted
with the needle cannula, and an outer tubular wall surface which
includes a lower segment proximate to said lower surrounding edge
portion, and configured such that, when said upper surrounding edge
portion is forced to extend toward said upper open end after said
tubular needle seat is inserted into said passage, said lower segment
will be brought to a position of use, where said lower segment engages
and is retained at said smaller-diameter segment by virtue of a
first friction force which is generated therebetween when said lower
surrounding edge portion abuts against said first surrounding shoulder
portion, and such that, when said upper surrounding edge portion
is moved against the first friction force toward said lower open
end passing said larger-diameter segment, said needle seat will
be brought to a retracted position, where said lower segment and
said lower surrounding edge portion are remote from said smaller-diameter
segment and said first surrounding shoulder portion, respectively,
and an upper segment disposed opposite to said lower segment and
proximate to said upper surrounding edge portion; and a plunger
including a stem portion disposed to be movable in said passage
of said barrel, and having inner and outer segments opposite to
each other in the longitudinal direction, said outer segment extending
outwardly of said lower open end, an actuated end extending from
said outer segment so as to be actuated to move said stem portion
along said passage, a surrounding engaging portion which is disposed
to retainingly sleeve on said inner segment by virtue of a second
friction force, and which is in sealing contact with and which is
slidable relative to said larger-diameter segment so as to be moved
with said stem portion to the position of use, and a head disposed
to extend from said inner segment toward said grip segment of said
inner tubular wall surface, and configured such that, when said
surrounding engaging portion is brought by said inner segment to
engage said lower surrounding edge portion and is depressed by said
lower surrounding edge portion by virtue of a third force which
is generated as a consequence of continuing movement of said inner
segment towards said smaller-diameter segment, the third force being
greater than the second friction force, said surrounding engaging
portion is retained by said lower surrounding edge portion to thereby
permit said head to move towards said grip segment and to be held
by virtue of a fourth friction force that is greater than the first
friction force.
2. The disposable syringe of claim 1 wherein said barrel has an
outer surrounding wall surface disposed opposite to said inner surrounding
barrel wall surface in radial directions, and having a sleeved portion
which is disposed proximate to said upper open end, said disposable
syringe further comprising a tip protector which has an internal
sleeve end configured to be sleeved on said sleeved portion so as
to shield the needle cannula.
3. The disposable syringe of claim 2 wherein each of said sleeved
portion and said internal sleeve end has a plurality of friction
ribs formed thereon.
4. The disposable syringe of claim 3 wherein said upper open end
has a surrounding edge wall which extends from said smaller-diameter
segment of said inner surrounding barrel wall surface toward the
axis and which confines a through hole that surrounds the axis and
that is adapted for passage of the needle cannula.
Description CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 10/143461 filed by the applicant on May 10
2002 the entire disclosure of which is incorporated herein by reference.
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
within a barrel after use for safe disposal.
[0004] 2. Description of the Related Art
[0005] In co-pending U.S. patent application Ser. No. 10/143461
the applicant disclosed a disposable syringe that includes a barrel,
a tubular needle seat, and a plunger. The barrel has an inner surrounding
barrel wall surface which confines a passage and which includes
a larger-diameter segment and a smaller-diameter segment that are
disposed proximate to lower and upper open ends, respectively, so
as to confine a surrounding shoulder portion therebetween. The tubular
needle seat is insertable into the passage, and includes a lower
surrounding edge portion which abuts against the surrounding shoulder
portion, and a surrounding seat wall which has an inner tubular
wall surface that has a grip segment, and an outer tubular wall
surface that includes a lower segment retained at the smaller-diameter
segment by virtue of a first friction force, and an upper segment
adapted to be sleeved over by a needle hub of a needle unit. The
plunger includes a stem portion which is movable in the passage
of the barrel and which has an outer segment that extends outwardly
of the lower open end of the barrel, a surrounding engaging portion
which is retainingly sleeved on an inner segment of the stem portion
by virtue of a second friction force and which is in sealing contact
with and which is slidable relative to the larger-diameter segment
so as to be moved with the stem portion, and a head which extends
from the inner segment toward the grip segment. As such, 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 against the second friction force
by a manual force which is generated as a consequence of continuing
movement of the inner segment, the surrounding 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. Therefore, the used needle
unit can be enclosed in the passage of the barrel for safe disposal.
[0006] It is desirable to improve the aforesaid disposable syringe
to simplify the construction thereof and to be adapted for use in
conjunction with needle units of various forms.
SUMMARY OF THE INVENTION
[0007] The object of the present invention is to provide a disposable
syringe which has a simpler construction and which is adapted to
be used in conjunction with needle units of various forms.
[0008] 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.
[0009] 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, which forms a grip segment, and which is
adapted to be fitted with a needle cannula, 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. The tubular needle seat is inserted into
the passage. Thus, the lower segment engages and is retained at
the smaller-diameter segment, and the lower surrounding edge portion
abuts against the surrounding shoulder portion.
[0010] 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.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] 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:
[0012] FIG. 1 is an exploded longitudinal sectional view showing
a first preferred embodiment of a disposable syringe according to
this invention for use with a needle cannula to form a syringe assembly;
[0013] FIG. 2 is a longitudinal sectional view showing the syringe
assembly during use;
[0014] FIG. 3 is a longitudinal sectional view showing the syringe
assembly in a retracted state;
[0015] FIG. 4 is a fragmentary longitudinal sectional view showing
a second preferred embodiment of a disposable syringe according
to this invention for use with a needle cannula;
[0016] FIG. 5 is a fragmentary longitudinal sectional view showing
a third preferred embodiment of a disposable syringe according to
this invention for use with a needle cannula; and
[0017] FIG. 6 is a fragmentary longitudinal sectional view showing
a fourth preferred embodiment of a disposable syringe according
to this invention for use with a needle cannula.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] 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.
[0019] Referring to FIGS. 1 2 and 3 the first preferred embodiment
of the disposable syringe according to the present invention is
shown to be used with a needle cannula 31 to form a syringe assembly.
[0020] The syringe in this embodiment is shown to comprise a barrel
10 a tubular needle seat 20 and a plunger 40.
[0021] The barrel 10 has an inner surrounding barrel wall surface
which surrounds an axis (X) and which confines a passage 12. The
passage 12 has lower and upper open ends 17 16 which are disposed
opposite to each other in a longitudinal direction that is parallel
to the axis (X). The inner surrounding barrel wall surface includes
a larger-diameter segment 131 and a smaller-diameter segment 134
which are disposed proximate to the lower and upper open ends 17
16 respectively, and which cooperatively form a first surrounding
shoulder portion 14 therebetween.
[0022] The barrel 10 further has an outer surrounding wall surface
which is disposed opposite to the inner surrounding barrel wall
surface in radial directions, and which has a sleeved portion 15
that is disposed proximate to the upper open end 16 and that is
formed with a plurality of friction ribs 133. A tip protector 32
has an internal sleeve end 321 which is configured to be sleeved
on the sleeved portion 15 for shielding the needle cannula 31 and
which has a plurality of longitudinally extending friction ribs
323 for engaging the friction ribs 133.
[0023] The tubular needle seat 20 is disposed to be insertable
into the passage 12 from the lower open end 17 toward the upper
open end 16. The needle seat 20 includes a lower surrounding edge
portion 23 disposed to abut against the first surrounding shoulder
portion 14 and having an outer surrounding surface 231 which abuts
sealingly against the larger-diameter segment 131 an upper surrounding
edge portion 223 disposed opposite to the lower surrounding edge
portion 23 in the longitudinal direction, and a surrounding seat
wall 22 interposed therebetween.
[0024] The seat wall 22 has an inner tubular wall surface 21 which
surrounds the axis (X) to confine a duct 24. The inner tubular wall
surface 21 has a narrow upper segment which is adapted to be fitted
with the needle cannula 31 and an enlarged lower segment which
forms a grip segment. In this embodiment, the grip segment includes
a concave portion 224 which extends inwardly from the inner tubular
wall surface 21 in radial directions relative to the axis (X) to
form a second surrounding shoulder portion 225 that is adjacent
to the lower surrounding edge portion 23.
[0025] The seat wall 22 further has an outer tubular wall surface
which includes lower and upper segments 221 222. The lower segment
221 is proximate to the lower surrounding edge portion 23 and has
a retaining protrusion 226 formed thereon. When the upper surrounding
edge portion 223 is forced to extend outwardly of the upper open
end 16 of the barrel 10 after the tubular needle seat 20 is inserted
into the passage 12 the lower segment 221 will be brought to a
position of use, as shown in FIG. 2 where the lower segment 221
engages and is retained at the smaller-diameter segment 134 by virtue
of a first friction force which is generated as a result of retaining
engagement between the retaining protrusion 226 and the smaller-diameter
segment 134 when an upper edge surface 232 of the lower surrounding
edge portion 23 abuts against the first surrounding shoulder portion
14 of the barrel 10. The upper segment 222 is disposed opposite
to the lower segment 221 and proximate to the upper surrounding
edge portion 223.
[0026] The plunger 40 includes a stem portion 46 which is movable
in the passage 12 of the barrel 10. The stem portion 46 has a plurality
of wing plates 47 a connecting shank 43 extending from upper edges
of the wing plates 47 and a retaining protrusion 42. On the other
hand, as shown in FIG. 2 the stem portion 46 includes inner and
outer segments 462 461 opposite to each other in the longitudinal
direction. The outer segment 461 extends outwardly of the lower
open end 17 of the barrel 10. An actuated end 48 which is a thumb
rest, extends from the outer segment 461 so as to be actuated to
move the stem portion 47 along the passage 12.
[0027] The plunger 40 further includes a tapered surrounding abutting
head 41 which extends from the retaining protrusion 42 of the inner
segment 462 toward the grip segment of the needle seat 20. Moreover,
the surrounding abutting head 41 and the retaining protrusion 42
are configured to be substantially hollow so as to provide greater
flexibility.
[0028] A deformable surrounding engaging portion 44 preferably
made of an elastic material, is retainingly sleeved on the entire
retaining protrusion 42 of the inner segment 462 and a portion of
the surrounding abutting head 41 to generate a second friction force.
An outer surrounding surface of the surrounding engaging portion
44 sealingly contacts, and is slidable relative to the larger-diameter
segment 131 of the barrel 10 so as to be moved with the stem portion
46.
[0029] In use, the plunger 40 is pressed forwardly to push the
surrounding engaging portion 44 to abut against the lower surrounding
edge portion 23 of the needle seat 20. Since the surrounding abutting
head 41 is configured to be fitted in the enlarged lower segment
of the inner tubular wall surface 21 drug solution in the passage
12 can be almost completely injected through the needle cannula
31.
[0030] Subsequently, referring to FIG. 3 when the plunger 40 is
further moved forward by a third force towards the smaller-diameter
segment 134 against the second friction force between the inner
segment 462 and the surrounding engaging portion 44 the surrounding
engaging portion 44 is deformed by the lower surrounding edge portion
23 thereby permitting the surrounding abutting head 41 to move
in the concave portion 224 of the needle seat 20 to abut against
the second surrounding shoulder portion 225 so as to form a fourth
friction force that is greater than the first friction force between
the retaining protrusion 226 and the smaller-diameter segment 134.
Then, the outer segment 461 of the plunger 40 is pulled backward
to be remote from the lower open end 17 so that the needle seat
20 on which the used needle cannula 31 is mounted, is retracted
into the passage 12 through the upper open end 16 to bring the upper
surrounding edge portion 223 to a retracted position. In this state,
the used needle cannula 31 can be enclosed in the passage 12 of
the barrel 20 for safe disposal.
[0031] In the syringe assembly of this invention, the number of
components is decreased since a needle hub is eliminated.
[0032] Referring to FIG. 4 the second preferred embodiment of
the disposable syringe is similar to the first preferred embodiment
in construction, and is used for an extremely small injection volume,
such as 1 ml. Thus, the dimensions of the barrel 10 the needle
seat 20 the needle cannula 31 and the plunger 40 are smaller than
those of the aforesaid embodiment.
[0033] Referring to FIGS. 5 and 6 the third and fourth preferred
embodiments of the disposable syringe according to this invention
are shown to be respectively similar to the first and second embodiments
in construction. The differences therebetween reside in that the
upper surrounding edge portion 223 is retained in the smaller-diameter
segment 134 of the barrel 10 in the position of use, and the upper
open end 18 of the barrel 10 has a surrounding edge wall 181 which
extends from the smaller-diameter segment 134 toward the axis (X)
and which confines a through hole 19 that surrounds the axis (X).
As such, the needle cannula 31 can pass through the through hole
19 and outwardly of the upper open end 18. The fourth preferred
embodiment shown in FIG. 6 is similar to the third preferred embodiment
in construction, but is used for an extremely small injection volume,
such as 1 ml.
[0034] While the present invention has been described in connection
with what is considered the most practical and preferred embodiments,
it is understood that this invention is not limited to the disclosed
embodiments but is intended to cover various arrangements included
within the spirit and scope of the broadest interpretations and
equivalent arrangements.
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