ZA200903303B

ZA200903303B - Safety disposable syringe

Info

Publication number: ZA200903303B
Application number: ZA200903303A
Authority: ZA
Inventors: Wen-Chin Lu
Original assignee: Global Ind Dev Corp
Priority date: 2009-05-13
Filing date: 2009-05-13
Publication date: 2010-04-28

Description

BE.

This inventionrelates toa safetydisposable syringe, more particularly to a safety disposable syringe includingabarrel and aneedle seat providedwitha canula and engageable with a piston on a plunger for withdrawing the canula into the barrel prior to disposal of the syringe. ~ Fig. 1 illustrates a conventional safety disposable syringe that includes a barrel 11, a plunger 14 extending into the barrel 11, a piston 15 mounted on the plunger 14 and formed with an engaging groove 151, and a needle seat 13 extending into thebarrel 11, connected toacanula 16, and formed with an engaging tongue 131 that is engageable with the engaging groove 151 so as to permit withdrawal of the canula 16 into the barrel 11 prior to disposal of the safety disposable syringe. The needle seat 13 is formed with a needle channel 133 for extension of the canula 16 thereinto,. and a fluid passage 132 : extending from one end of the needle channel 133 through an end face 1311 of the engaging tongue 131 so as to permit fluid communication between the canula 16 and a chamber of the barrel 11. However, since the fluid passage 132 : passes through the engaging tongue 131, the latter ’ requires a larger size to allow formation of the fluid passage 132 therethrough. As such, the design of the aforesaid safety disposable syringe is not suitable for application to small sized syringes, i.e., syringes that

Therefore, the object of the present invention is to provide a safety disposable syringe that can overcome the aforesaid drawback associated with the prior art.

According to this invention, a safety disposable syringe comprises: a barrel having front and rear open ends and defining a chamber therein and an axis; a plunger : extending through the rear open end and into the chamber and having a front end; a piston mounted on the front end of the plunger and formedwitha first engaging member; a canula; and a needle seat extending fittingly through the front open end of the barrel and having a front end disposed outwardly of the chamber, anda rear end disposed in the chamber and having a rear end face facing toward the piston. The needle seat defines a central channel - extending through the front end of the needle seat for extension of the canula thereinto, and a fluid passage extending through the rear end face of the rear end of the needle seat and in fluid communication with the central channel and the chamber. The rear end face of the rear end of the needle seat is formed with a second engaging member that is axially aligned and that is engagable with the first engaging member. The fluid passage has a first terminating end terminated at the rear end face of the rear end of the needle seat, and asecondterminatingendoppositetothe first terminating end and terminated at the rear end face of the rear end of the needle seat. The second engaging member has a terminating end terminated at the rear end face of the rear end of the needle seat and spaced apart from the : first terminating end of the fluid passage. The needle seat has an outer surface surrounding the axis. The fluid passageisgenerallyU-shapedandhasaradiallyextending section extending radially through the outer surface, and two axially extending sections extending respectively from two ends of the radially extending : section to the first and second terminating ends. The fluid passage is indented inwardly and radially from the outer surface along an axial length of the outer surface. oo Other features and advantages of the present invention : will become apparent in the following detailed. descriptionof thepreferredembodiments of the invention, with reference to the accompanying drawings, in which:

Fig. 1 is a partly sectional view of a conventional safety disposable syringe;

Fig. 2 is an exploded perspective view of the first : 20 ‘preferred ‘embodiment of a safety disposable syringe according to this invention;

Fig. 3 is a schematic top view of the first preferred embodiment;

Fig. 4 is a fragmentary, partly sectional view of the first preferred embodiment;

Fig. 5 is a sectional view of a needle seat of the first preferred embodiment;

: Fig. 6 is a fragmentary, partly sectional view illustrating how a fluid in a barrel is delivered through a fluid passage and a canula of the first preferred embodiment;

Fig. 7 is a fragmentary, partly sectional view illustrating how apiston is brought into engagement with the needle seat of the first preferred embodiment; : Fig. 8 is a fragmentary, partly sectional view illustrating how the needle seat together with the canula is withdrawn into the barrel of the first preferred : embodiment;

Fig. 9 is a fragmentary, partly sectional view illustrating how a portion of a plunger is removed after the needle is withdrawn into the barrel of the first preferred embodiment; .

Fig. 10 is a sectional view of the needle seat of the second preferred embodiment of the safety disposable syringe according to this invention; and

Fig. llisapartlysectionalviewillustratinga state where the needle seat together with the canula tilts at : an angle relative to the axis after being withdrawn into the barrel of the second preferred embodiment.

Before the present invention is described in greater detail, it should be noted that same reference numerals : have been used to denote like elements throughout the specification.

Referring to Figs. 2 to 5, the first preferred embodiment of a safety disposable syringe according to : the present invention is shown to include: a barrel 3 having front and rear open ends 31, 32 and defining a chamber 30 therein for receiving a medicine and an axis (X); a plunger 5 extending through the rear open end 32 and into the chamber 30 and having a front end 51 formed ; with a protrusion 511; a piston 6 mounted on the front end 51 of the plunger 5 and formed with a rear recess 621 for extension of the protrusion 511 therein, and a first engaging member 611’ opposite to the rear recess 621; a canula 2; and a needle seat 4 extending fittingly through the front open end 31 of the barrel 3 and having a front end 41 disposed outwardly of the chamber 30, and a rear end 42 disposed in the chamber 30 and having a

E 15 rear end face 420 facing toward the piston 6. The needle - ‘seat 4 further has an outer surface surrounding the axis : (X), and defines a central channel 45 extending through the front end 41 of the needle seat 4 for extension of the canula 2 thereinto, and a fluid passage 46 extending through the rear end face 420 of the rear end 42 of the needle seat 4 and in fluid communication with the central channel 45 and the chamber 30. The rear end face 420 of the rear end 42 of the needle seat 4 is formed with a second engaging member 44’ that is axially aligned and that is engagable with the first engaging member 611’ (see Fig. 7). ‘The fluid passage 46 is generally U-shaped, and has a first terminating end 460 (see Fig. 5) terminated at the rear end

. § face 420 of the rear end 42 of the needle seat 4, and a second terminating end 465 opposite to the first terminating end 460 and terminated at the rear end face 420 of the rear end 42 of the needle seat 4. The second engaging member 44’ has a terminating end 440 (see Fig. 5) . terminated at the rear end face 420 of the rear end 42 of the needle seat 4 and spaced apart fromthe first terminating end 460 of the fluid passage 46. The fluid passage 46 has a radially extending section 462 extending radially through the outer surface, and two axially extending sections 461 extending respectively from two ends of the radially extending section 462 to the first and second terminating ends 460, 465. The fluid passage 46 is indented inwardly and radially from the outer surface i 15 of the needle seat 4 along an axial length of the outer . surface of the needle seat 4.

Preferably, the first and second engaging members 611", 44" are engageable with each other in a tongue-and-groove engaging manner. In this embodiment, the piston 6 is formed with an engaging groove 611 that defines the first engaging member 611’, and the rear end face 420 of the . rear end 42 of the needle seat 4 is formed with an engaging tongue 44 that defines the second engaging member 44°.

Preferably, the volume of the fluid passage 46 is : substantially equal to that of the engaging groove 611 so that when the entire body of the medicine received in the barrel 3 is driven out, the air trapped in the engaging groove 611 can be used to drive out residual medicine retained in the fluid passage 46 upon engagement of the engaging groove 611 with the engaging tongue 44.

This can avoid waste of the medicine from occurring.

In this embodiment, each of the axially extending sections 461 of the fluid passage 46 has a depth (d) in . a radial direction relative to the axis (X) and a width a (w) in a direction transverse to the radial direction and the axis (X). The ratio of the width of each of the axially extending sections 461 of the fluid passage 46 to a perimeter of the rear end 42 of the needle seat 4 : is preferably less than 1/15. The ratio of the depth of each of the axially extending sections 461 of the fluid passage 46 to a diameter of the rear end 42 of the needle seat 4'is preferably less than 1/7. In this embodiment, the width of each of the axially extending sections 461 of the fluid passage 46 is 0.5mm, and the depth of each of the axially extending sections 461 of the fluid passage 46 is 0.5mm.

In this embodiment, the needle seat 4 is in the form of a single piece. The engaging tongue 44 extends along the axis (X) of the barrel 3. The first and second terminating ends 460, 465 of the fluid passage 46 are disposed at two sides of the engaging tongue a4. : The front end 41 of the needle seat 4 has a front end face 410. The central channel 45 has a first section 451 extending from the front end face 410 of the front end

; 41 of the needle seat 4, a second section 452 extending fromthe first section 451, a third section 453 extending from the second section 452, and a fourth section.454 extending from the third section 453 to the fluid passage 46. The first section 451 converges in dimensions from the front end face 410 of the front end 41 of the needle seat 4 to an adjacent end of the second section 452. The second section 452divergesindimensions fromanadjacent : end of the first section 451 to an adjacent end of the third section 453 so as to forma constriction 455 between the first and second sections 451, 452 for constricting the canula 2. A glue 8 fills the first section 451 of the central channel 45 to fix the canula 2 to the needle seat 4. The rear end 42 of the needle seat 4 is formed with a neck 421. The barrel 3 is formed with an inner shoulder 3111 disposed adjacent to the front open end 31 of the barrel 3 and abutting against the neck 421 of the rear end 42 of the needle seat 4 so as to prevent undesired removal of the needle seat 4 through the front open end 31 of the barrel 3.

The needle seat 4 has a tubular wall 40 (see Figs. 2 and 5) that defines the central channel 45 therein, apluralityof angularly displaced fins 43 radiating from an outer surface of the tubular wall 40 and in frictional contact with an inner surface of the front open end 31 of the barrel 3, and an annular flange 471 connected to ~ ends of the fins 43. The needle seat 4 is formed with

9 a anannularretaininggroove 431 betweentheannular flange 471 and the radially extending section 462 of the fluid passage 46. A sealing ring 47 is retained in the retaining groove 431, and is in sealing contact with the inner surface of the front open end 31 of the barrel 3. ‘The barrel 3 has a rear end portion having an inner surface that has acylindrical rear segment 321 extending fromthe rear open end 32 of the barrel 3, a middle segment 323, and a transition segment 322 interconnecting the rear segment 321 and the middle segment 323 and diverging in cross-section from the rear segment 321 to the middle segment 323. The plunger 5 further has a rear end 52, and is formed with an annular notch 513 disposed between the front and rear ends 51, 52 of the plunger 5, a first annular flange 512 axially spaced apart from the annular notch 513, and a second annular flange 512’ disposed between the annular notch 513 andthe first annular flange 512. The annular notch 513 is disposed between the second annular flange 512’ and the rear end 52 of the plunger 5. The second annular flange 512’ has a diameter substantially equal to that of the rear segment 321 of the barrel 3. The first annular flange 512 has a diameter substantially equal to that of the transition segment 322 of the barrel 3.

Referring to Figs. 6 to 8, in operation, a fluid 9 in the barrel 3 is pushed by an external force acting on the plunger 5, and passes through the fluid passage

46 and the canula 2 for injection into a patient. When the engaging groove 611 in the piston 6 is brought into full engagement with the engaging tongue 44, the fluid 9 in the barrel 3 is completely expelled therefrom, as best illustrated in Fig. 7. When the safety disposable ‘syringe is to be discarded after use, the plunger 5 is pulled back so as to withdraw the needle seat 4 together with the canula 2 into the barrel 3, as best illustrated inFig. 8. When the first annular flange 512 of the plunger

Sis brought into abutment against the transition segment 322 of the inner surface of the rear end portion of the barrel 3, further rearward movement of the plunger 5 is prevented. At this state, the annular notch 513 is : substantially flush with a rear end face 320 of the barrel 3, thereby permitting breaking of the plunger 5 at the : annular notch 513 (see Fig. 9). : Figs. 10 and 11 illustrate the second preferred embodiment of the safety disposable syringe according to this invention. The second preferred embodiment differs fromthe previous embodiment in that the engaging tongue 14 is tilted relative to the axis (X) of the barrel 3, while the engaging groove 611 extends along the axis (X) of the barrel 3.

As illustrated in the preferred embodiments, by forming the fluid passage 46 in the needle seat 4 such © that it does not pass through the second engaging member 44° (i.e., the engaging tongue 44 formed on the rear end face 420 of the rear end 42 of the needle seat 4), the size of the second engaging member 44’ can be kept as

A small as possible as long as engagement between the first : and second engaging members 611°, 44’ is sufficient to permit withdrawal of the needle seat 4 into the barrel 3 by the plunger 5, thereby eliminating the aforesaid drawback associated with the prior art. Lo

Claims

oo Co Lim CLAIMS:

1. A safety disposable syringe comprising: a barrel (3) having front and rear open ends (31, 32) and defining a chamber (30) therein and an axis Cs wm a plunger (5) extending through said rear open end (32) and into said chamber (30) and having a front end (51); a piston (6) mounted on said front end. (51) of said plunger (5) and formed with a first engaging member - (6117); a canula (2); and a needle seat (4) extending fittingly through said front open end (31) of said barrel (3) and having a

15 . front end (41) disposed outwardly of said chamber (30), and a rear end (42) disposed in said chamber (30) and having a rear end face (420) facing toward said piston (6), said needle seat (4) defining a central channel . (45) extending through said front end (41) of said needle seat (4) for extension of said canula (2) thereinto, and a fluid passage (46) extending through said rear end face (420) of said rear end (42) of said needle seat (4) and in fluid communication with said central channel (45) and said chamber (30), said rear end face (420) of said rear end (42) of said needle seat (4) being formed with a second engaging member (44') that is axially aligned and that is engagable with said first

, to K2009/033505 engaging member (611'); wherein said fluid passage (46) has a first : terminating end (460) terminated at said rear end face (420) of said rear end (42) of said needle seat (4), and a second terminating end (465) opposite to said first terminating end (460) and terminated at said rear : end face (420) of said rear end (42). of said needle seat (4); wherein said second engaging member (44’) has a : terminating end (440) terminated at said rear end face (420) of said rear end (42) of said needle seat (4) and spaced apart from said first terminating end (460) of said fluid passage (46); wherein said needle seat (4) has an outer surface : surrounding the axis (X), said fluid passage (46) being generally U-shaped and having a radially ‘extending section (462) extending radially through said outer surface, and two axially extending sections (461) . extending respectively from two ends of said radially extending section (462) to said first and second terminating ends (460, 465); and : wherein said fluidpassage (46) is indented inwardly and radially from said outer surface along an axial length of said outer surface of said needle seat (4).

2. The safety disposable syringe of claim 1, wherein said first and second engaging members (6117, 447) are engageable with each other in a tongue-and-groove engaging manner.

3. The safety disposable syringe of claim 2, wherein said piston (6) is formed with an engaging groove (611) that" defines said first engaging member (611'), said rear | end face (420) of said rear end (42) of said needle seat (4) being formed with an engaging tongue (44) that . . defines said second engaging member (44').

4. The safety disposable syringe of claim 3, wherein the volume of said fluidpassage (46) is substantially equal to that of said engaging groove (611). .

5. The safety disposable syringe of claim 1, wherein each of said axially extending sections (461) of said fluid passage (46) has a depth (d) in a radial direction + relative to the axis (X) and a width (w) in a direction transverse to the radial direction and the axis (X), the ratio of the width (d) of each of said axially extending sections (461) of said fluid passage (46) to a perimeter of said rear end (42) ‘of said needle seat (4) being less than 1/15, the ratio of the depth (d) of each of said axially extending sections (461) of said fluid passage (46) to a diameter of said rear end (42) of said needle seat (4) being less than 1/7.

6. The safety disposable syringe of claim 3, wherein said needle seat (4) is in the form of a single piece, said engaging tongue (44) extending along the axis (X) of said barrel (3), said first and second terminating ends : (460, 465) of said fluid passage (46) being disposed at two sides of said engaging tongue (44).

7. The safety disposable syringe of claim 3, wherein said : front end (41) of said needle seat (4) has a front end face (410), said central channel (45) having a first section (451) extending from said front end face (410) of said front end (41) of said needle seat (4), a second section (452) extending from said first section (451), athirdsection (453) extending fromsaid second section (452), and a fourth section (454) extending from said third section (453) to said fluid passage (46), said first section (451) converging in dimensions from said front end face (410) of said front end (41) of said = . . needle seat (4) toanadjacent endof said second section (452), said second section (452) diverging in | dimensions from an adjacent end of said first section ) : (451) to an adjacent end of said third section (453) So as to form a constriction (455) between said first and second sections (451, 452) for constricting said canula (2).

8. The safety disposable syringe of claim 1, wherein said needle seat (4) has a tubular wall (40) that defines said central channel (45) therein, and a plurality of angularly displaced fins (43) radiating from an outer surface of said tubular wall (40) and in frictional contact with an inner surface of said front open end (31) of said barrel (3).

9. The safety disposable syringe of claim 1, wherein said barrel (3) further has a rear end portion having an inner surface that has acylindrical rear segment (321) extending from said rear open end (32) of said barrel (3), a middle segment (323), and a transition segment (322) interconnecting said rear segment (321) and said middle segment (323) and diverging in cross-section } from said rear segment (321) to said middle segment . (323) , said plunger (5) further having a rear end (52) and being formed with an annular notch (513) disposed: between said front and rear ends (51, 52) of said plunger (5), a first annular flange (512) axially spaced apart from said ‘annular notch (513), and a second annular flange (512’) disposed between said annular notch (513) ] and said first annular flange (512), said annular notch (513) being disposed between said second annular flange : (512") and said rear end (52) of said plunger (5), said second annular flange (5127) having a diameter substantially equal to that of said rear segment (321) of said barrel (3), said first annular flange (512) - having a diameter substantially equal to that of said transition segment (322) of said barrel (3). .

10. The safety disposable syringe of claim 11, wherein said engaging tongue (44) is tilted relative to the : axis (X) of said barrel (3), said engaging groove (611) extending along the axis (X) of said barrel (3). :

11. The safety disposable syringe of claim 1, wherein said rear end (42) of said needle seat (4) is formed with a neck (421), said barrel (3) being formed with an inner shoulder (3111) disposed adjacent tosaid front open end (31) of said barrel (3) and abutting against said neck (421) of said rear end (42) of said needle seat (4).

12. The safety disposable syringe of claim 1, wherein said needle seat (4) is formed with an annular retaining } groove (431), said safety disposable syringe further : | comprising a sealing ring (47) retained in said retaining groove (431) and in sealing contact with said front open end (31) of said barrel (3). 77 THIS 13TH DAY OF MAY 2009 Na V4 : £7] - APPLICAND PATENT ATTORNEYS