Single-use syringe

Abstract

A single-use syringe includes a deformable sealing member which is in a fluid-tight and slidable engagement with a barrel wall, a plunger which is disposed to be movable along the barrel wall, a first coupling member which is secured to a front end wall of the plunger, and which has a first connected end disposed forwardly of the front end wall, and a second coupling member which is secured to a trail end wall of the sealing member, and which has a second connected end disposed rearwardly of the trail end wall. The second connected end confronts the first connected end in a radial direction, and is attached to the first connected end at a bonding region. Immediately after the second connected end stays put as a result of abutment of the sealing member against a shoulder of the barrel, a subsequent forward force applied to the plunger breaks the bonding region, thereby preventing operation of the plunger to move the sealing member rearward, and thereby rendering the syringe unreusable.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiments of the invention, with reference to the accompanying drawings, in which:

FIG. 1 is a sectional view of a conventional single-use syringe;

FIG. 2 is a sectional view of the conventional single-use syringe of FIG. 1 after use;

FIG. 3 is an exploded sectional view of the first preferred embodiment of a single-use syringe according to this invention;

FIG. 4 is a sectional view of the first preferred embodiment during an injection stroke;

FIG. 5 is a sectional view showing the first preferred embodiment in a state after completion of the injection stroke;

FIGS. 6 to 8 are fragmentary sectional views of the first preferred embodiment, showing how a deformable sealing member is separated from a plunger of the syringe;

FIG. 9 is a sectional view of the second preferred embodiment of a single-use syringe according to this invention;

FIG. 10 is a sectional view showing the second preferred embodiment in a state where a deformable sealing member is separated from a plunger of the syringe;

FIG. 11 is a sectional view of the third preferred embodiment of a single-use syringe according to this invention;

FIG. 12 is a fragmentary sectional view showing the third preferred embodiment in a state after completion of the injection stroke;

FIG. 13 is a sectional view showing the third preferred embodiment in a state where a deformable sealing member is separated from a plunger of the syringe;

FIGS. 14 and 15 are fragmentary sectional views of the fourth preferred embodiment of a single-use syringe according to this invention;

FIGS. 16 and 17 are fragmentary sectional views of the fifth preferred embodiment of a single-use syringe according to this invention;

FIG. 18 is a fragmentary sectional view of the sixth preferred embodiment of a single-use syringe according to this invention;

FIGS. 19 and 20 are fragmentary sectional views of the seventh preferred embodiment of a single-use syringe according to this invention;

FIG. 21 is a fragmentary sectional view of the eighth preferred embodiment of a single-use syringe according to this invention;

FIG. 22 is a sectional view of the ninth preferred embodiment of a single-use syringe according to this invention;

FIGS. 23 to 25 are sectional views of the tenth preferred embodiment of a single-use syringe according to this invention, showing how a deformable sealing member is separated from a plunger of the syringe;

FIG. 26 is a sectional view of the eleventh preferred embodiment of a single-use syringe according to this invention;

FIG. 27 is a sectional view showing the eleventh preferred embodiment in a state after completion of the injection stroke; and

FIG. 28 is a sectional view showing the eleventh preferred embodiment in a state where a deformable sealing member is separated from a plunger of the syringe.

Claims

1. A single-use syringe comprising: a barrel including front and rear barrel ends opposite to each other along an axis in an axial direction, and a surrounding barrel wall which interconnects said front and rear barrel ends, and which includes small-diameter and large-diameter wall portions that are disposed proximate to said front and rear barrel ends, respectively, and that respectively have front and rear inner wall surfaces respectively defining a passage and an accommodation chamber which are in fluid communication with each other, anda shoulder that is interposed between said small-diameter and large-diameter wall portions;a needle cannula having a rear secured end and a front tip end opposite to each other along the axis, said rear secured end being affixed to said small-diameter wall portion to be communicated with said passage such that said front tip end is exposed outwardly of said front barrel end in use;a plunger which is disposed to be movable in said accommodation chamber along said large-diameter wall portion, said plunger having a front end wall which confronts said passage, and a rear end wall which extends outwardly of said rear barrel end to be manually operable;a hollow deformable sealing member including a head end wall which confronts said shoulder, and a deformable surrounding wall which extends from said head end wall rearwardly, which is in a fluid-tight and slidable engagement with said large-diameter wall portion so as to permit said head end wall to be brought to abut against said shoulder, and which terminates at a trail end wall;a first coupling member including a first secured end which is secured to said front end wall, and a first connected end which is disposed opposite to said first secured end in the axial direction and forwardly of said front end wall; anda second coupling member including a second secured end which is secured to said trail end wall, and a second connected end which is disposed opposite to said second secured end and rearwardly of said trail end wall, said second connected end confronting said first connected end in a radial direction relative to the axis, and being attached to said first connected end at a bonding region with a bonding force such that the bonding force is greater than a frictional force generated between said deformable surrounding wall and said large-diameter wall portion when said plunger is forced to move in said accommodation chamber, and such that immediately after said second connected end stays put as a result of abutment of said head end wall against said shoulder, a subsequent forward force applied to said rear end wall of the plunger imparts to said bonding region a shear force which breaks said bonding region when the shear force is greater than the bonding force, thereby preventing operation of said plunger to move said deformable sealing member rearward, and thereby rendering said syringe unreusable.

2. The single-use syringe of claim 1, wherein said second connected end of said second coupling member has an outer sliding surface which extends in the axial direction so as to guide said bonding region to slide thereon once said bonding region is broken by the subsequent forward force.

3. The single-use syringe of claim 2, wherein said outer sliding surface has an inclined segment which is disposed proximate to said second secured end and which is inclined from the axis to said second secured end such that when said bonding region slides along said inclined segment, said second connected end is bent toward the axis so as to acquire a biasing force that imparts to said bonding region an increased force component in the axial direction to thereby facilitate rearward movement of said bonding region relative to said inclined segment.

4. The single-use syringe of claim 3, wherein said second coupling member has left and right bendable units which cooperatively serve as said second connected end, and which are spaced apart from each other in a radial direction to define an axial clearance therebetween so as to provide a leeway for said left and right bendable units to be bent toward the axis; and wherein said first coupling member has left and right sliding units which cooperatively serve as said first connected end, and which confront respectively said left and right bendable units in the radial direction, and which are spaced apart from each other in the radial direction to confine therebetween an axial channel so as to accommodate said left and right bendable units when said bonding region slides along said inclined segment.

5. The single-use syringe of claim 1, further comprising a plug which is connected to one of said head end wall of said deformable sealing member and said second secured end of said second coupling member, and which extends forwardly from said head end wall such that when said head end wall is brought to abut against said shoulder, said plug is forced to plug said passage, said plug having frictional ribs that are configured to frictionally engage said small-diameter wall portion with enhanced friction.

6. The single-use syringe of claim 1, further comprising an encasing member which is configured to be sleevable on said surrounding barrel wall from said front barrel end, and which includes a surrounding front segment that surrounds said small-diameter wall portion, and that permits said needle cannula to extend outwardly thereof and to be retractable thereinto, anda surrounding rear segment that extends from said surrounding front segment in the longitudinal direction to be sleeved on said large-diameter wall portion, and that is movable relative to said barrel between a position of use, where said small-diameter wall portion is closer to said surrounding front segment, and where said needle cannula extends outwardly of said surrounding front segment, and a disposal position, where said small-diameter wall portion is remote from said surrounding front segment, and where said needle cannula is disposed inwardly of said surrounding front segment as a result of withdrawal of said small-diameter wall portion from said surrounding front segment.

7. The single-use syringe of claim 6, wherein said large-diameter wall portion and said rear surrounding segment respectively have a spirally extending recess and a protrusion which are angularly engageable when said encasing member is sleeved on said barrel so as to prevent said surrounding barrel wall from displacing along said surrounding rear segment in the axial direction, thereby placing said surrounding barrel wall in the position of use, and which are configured such that said surrounding barrel wall is angularly movable relative to said surrounding rear segment so as to enable subsequent axial displacement of said surrounding barrel wall from the position of use to the disposal position.

8. The single-use syringe of claim 7, wherein said large-diameter wall portion has a surrounding retaining groove which is formed adjacent to said small-diameter wall portion and which is opposite to said spirally extending recess in the axial direction so as to engage said protrusion when said surrounding barrel wall is in the disposal position, thereby preventing said surrounding barrel wall from displacing along said surrounding rear segment.

9. The single-use syringe of claim 8, wherein said large-diameter wall portion further has a guideway which extends to interconnect said spirally extending recess and said surrounding retaining groove so as to facilitate the displacement of said surrounding barrel wall from the position of use to the disposal position.

10. The single-use syringe of claim 5, further comprising a tip protector which is detachably sleeved on said surrounding front segment of said encasing member for shielding said needle cannula.

11. The single-use syringe of claim 1, wherein said surrounding barrel wall has a larger thickness at said small-diameter wall portion, and a smaller thickness at said large-diameter wall portion.

12. The single-use syringe of claim 11, wherein said small-diameter wall portion has an inner grip surface which defines said passage and which is configured such that said rear secured end of said needle cannula is in a fluid-tight engagement with said inner grip surface.

13. The single-use syringe of claim 11, further comprising a tip protector which is detachably sleeved on said small-diameter wall portion for shielding said needle cannula and which is disposed to be in a fluid-tight engagement with a portion of said large-diameter wall portion.

14. The single-use syringe of claim 5, wherein said passage includes a wider passage segment which extends from said shoulder forwardly and which is dimensioned such that said plug is tightly fitted thereinto, and a narrower passage segment which is disposed between said wider passage segment and said front barrel end.

15. The single-use syringe of claim 14, wherein said small-diameter wall portion has an inner grip surface which defines said narrower passage segment and which is configured such that said rear secured end of said needle cannula is in a fluid-tight engagement with said inner grip surface.

16. The single-use syringe of claim 1, further comprising: a tubular needle seat having a tubular retaining portion which retains said rear secured end of said needle cannula to permit forward extension of said front tip end from said tubular retaining portion, and a tubular sleeve portion which is opposite to said tubular retaining portion along the axis to define a duct that is fluidly communicated with said needle cannula, and which is detachably sleeved on said small-diameter wall portion to fluidly communicate said duct with said passage; anda tip protector which is removable and is in a fluid-tight engagement with said tubular sleeve portion for shielding said needle cannula.

17. The single-use syringe of claim 1, wherein said barrel includes a tubular guard portion which extends rearwardly from said rear barrel end and which defines a receiving space communicated with said accommodation chamber, said plunger having a thumb rest which extends rearwardly and outwardly of said tubular guard portion for manual operation, and which is received in said receiving space when said deformable sealing member reaches said shoulder.