GB2233901A

GB2233901A - Disposable hypodermic syringe with retractable needle

Info

Publication number: GB2233901A
Application number: GB8915919A
Authority: GB
Inventors: Hugh Williams
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-07-11
Filing date: 1989-07-11
Publication date: 1991-01-23
Also published as: DD296421A5; GB8915919D0; ZA905430B

Abstract

A non-deformable disposable hypodermic syringe, wherein after the use the needle, 3, can be fully retracted into the barrel, 4, to prevent accidental stabbing and risk of infection. Comprises a hub, 1, embodying a needle holder tube, 2, provided with internal barbs, 2b, which (after use) engage a domed head 7, of a plunger, 5. During use (suction and injection delivery) the said plunger domed head, 7 is retained behind a membrane, 9m, and within the piston, 9, by a similar internal barb, 9b, inside the piston, 9. <IMAGE>

Description

DISPOSABLE HYPODERMIC SYRINGE WITH RETRACTABLE NEEDLE This invention relates to a disposable hypodermic syringe wherein after use the needle can be fully retracted into the barrel to prevent accidental stabbing, and consequential risk of infection from contaminated needles, which has now become an even more important issue, with the advent of communicable diseases such as AInS and Hepatitis.

The object of the present invention is to provide a fool-proof disposable hypodermic syringe embodiment for the needle to be conveniently and completely retracted (after use) into the syringe barrel safely out of harms way, without a significant increase in the cost of the syringe.

PRIOR ART A Database search on the ;,orld Patent Index has revealed five Applications for a "Disposable Hypodermic Syringe with !Retractable Needle". None of these applications anticipate the embodiments of the present invention for the reasons stated below: US 4790822: The master claim 1 embodies 'providing said barrel with semi-rigid deformable wall', also claim lc 'providing said plunger with expanding means to deform said walls; in the present invention claim 1 embodies 'a significantly non-deformable syringe barrel'.

US 4,767,413, US 4,258,713 and WO 89/00435 embody an axial compression spring means to retract needle; the present invention does not embody any compression springs.

US 4,790,#27 essentially embodies a vacuum tube phlebotomy (instead of a piston and plunger) and also embodies an outer shield rather than a retractable needle, neither of which are embodied in the present invention.

RE:FER NCE: TO DRAWINGS Specific embodiments of the Syringe Invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is an external view of an assembled syringe.

Figure 2 is an internal part sectional view of the syringe barrel sub-assembly and needle holder sub-assembly prior to assembly.

Figure 3 is a sectional view of the assembled syringe.

Figure 4 is an external isometric view of an assembled syringe.

Figure 5 is an internal part section isometric view of the syringe sub-assembly and needle holder sub-assembly prior to assembly.

Figure 6 is an isometric ghost view of a fully assembled syringe.

Figure 7 is a sectional view of syringe showing the domed head of the plunger, fully engaged and entrapped in the needle holder barbs, prior to unscrewing and retraction.

Figure 8 is a sectional view of syringe showing needle holder fully retracted and plunger broken off at weak section.

Figure 9 is a sectional view of a syringe embodying eccentric barrel.

DESCRIPTION OF PREFERRED EMBODIMENTS OF INVENTION Referring to the drawings there is provided a disposable hypodermic syringe comprizing a separate attachable hub, 1, wherein the said hub, 1, embodies a concentric needle holder, 2, with an internal integral hypodermic needle, 3, wherein said holder, 2, is separable from the hub, 1, and fully retractable (after use) into a (significantly) non-deformable syringe barrel, (or syringe cylinder), 4.

To facilitate retraction male engaging means is provided at the end of the plunger, 5, comprizing a fluted, Sf, and/or necked shaft, 6, terminating with an integral domed and/or button shaped head, 7. A female mating engaging means is provided on the needle holder comprizing a hollow tube, 2t, having a matching mating internal diameter with the said domed head, 7, of the plunger, 5, and provided with internal integral sprung barbs, 2b, head, 7, until the said barbs, 2b, spring back internally onto the said fluted neck, Sf, behind the said darned head, 7, to entrap the said domed head, 7.

preferably the integral embodiment of the needle, 3, and the needle holder tube, 2t, are made intergral by the provision of an inert jointing medium, 2m, and/or integral inert plastic moulding, 2m. To prevent premature retraction (of the needle, 3, and needle holder, 2,) into the barrel, 4, the said domed head, 7, of the plunger, 5, is retained behind the piston face, 9f, and within the piston, 9, by a rubber (or synthetic rubber) membrane, 9m, so provided to form the piston head, 9f, or pressure face, 9f, of the piston, 9.

Preferably the said membrane, am, comprizes an integral moulding, Qim, with the piston, 9, and/or piston sealing rings, 9r.

Dreferably the separable embodiment between said needle holder tube, 2t, and said hub, 1, comprises an external screw thread, 2ts, on the needle holder tube, 2t. and a matching mating internal thread, is, on the corresponding mating section of the hub, 1.

Preferably the said hub, 1, is manufactured in an inert plastic material and the thread form and tolerances of the said mating threads, 2ts and is, embody an airtight and/or a liquid tight seal, and are also unscrewable by twisting the said plunger, 5, after it is entrapped by the said barbs, 2b, acting against the flutes, 6f, of the said necked fluted plunger shaft, 6.

In order to facilitate withdrawal of the piston, 9, during the suction stroke the said piston, 9, is provided with an internal concentric tube, 9t, also provided with internal integral sprung barbs, 9b, formed out of the wall of the tube, 9t, and so provided to enable entry of the said plunger domed head, 7, (during manufacturing assembly) into the piston, 9, until the said piston tube barbs, 9b, spring inwardly behind the said domed head, 7, on to the neck, S, of the plunger, 5, to entrap the domed head, 7, (thus facilitating withdrawal of the piston during the suction stroke of the syringe).

Preferably to facilitate needle engagement/needle retraction, the length of the said neck section, 6, of the plunger, 5, is so provided so as to permit sufficient forward movement of the plunger, 5, to enable penetration beyond the said piston face, of, and into the said needle holder tube barbs, 2b, (when said needle engagement/retraction is required).

Preferably the said hub, 1, is attached to syringe barrel, 4, by the provision of a concentric mating tapered shaped male nozzle, 4n, on said syringe barrel, 4, and the provision of a matching air tight and/or liquid tight internal taper, it, within said hub, I.

Preferably the gradient of the said taper, lt, used is 6% and/or any standard taper to conform with the accepted medical standards prevailing.

Preferably finger grips, 10, are provided on the syringe barrel, 4, at the plunger, 5, operating end of the said barrel, 4.

Preferably a concentric bush or collar, 11, is provided inside the said barrel, 4, at the said finger grip, 10, end, together with integral matching shoulder stops, 12 and 13, provided at suitable locations on both ends of the plunger rod, Sr, to act as stops to prevent premature penetration of the said piston head membrane, 9m, and also to prevent premature dismantling of the syringe assembly during the suction stroke respectively.

Preferably the dimensional tolerances of the said bush, 11, is so provided that its outside mating diameter, 1 leo, is an interferance (but movable) fit with the mating bore, 4b, of the said barrel, 4, and also the inside mating diameter, lid, of the said bush, 11, is an easy slide fit with the said mating plunger rod, 5r.

Preferably the said bush, 11, is provided with a circumferencial split, Ills, to enhance feasibility of the said above mentioned fits.

Preferably a weal spot or weak section, 5w, is provided on an appropriate location of the plunger rod, 5r, to enable it to be broken off after the said needle holder, 2, and needle, 3, have been full retracted (after use) into the said barrel, 4.

Preferably the said hub, 1, and syringe barrel, 4, are additionally provided with a mating thread fitting, if and 4f, to reinforce the said airtight and/or liquid tight seal between the said taper, It, and nozzle, 4n, fitting.

Preferably the said mating screw thread fitting, If and 4f, provided conforms with Rritish Standard 3930 part 2, and/or any accepted medical standards prevailing.

Preferably to reinforce sealing between needle holder tube, 2, and barrel, 4, there is provided an O-ring seal, 14, located around the said needle holder tube, 2, and between the end face, 4nf, of the said syringe barrel nozzle, 4n, and the mating internal face, lif, of the said hub, 1, to act as ar additional li.qui# ujd or airtight seal.

Preferably to further reinforce said sealing there is provided an additional O-ring seal, 1 R, located around the said needle, 3, and between the end face, 2f, of the said needle holder, 2, and the mating internal face, Ifif, of the said hub, 1, to serve as an additional liquid tight and/or airtight seal.

In order to increase the versatility of the said syringe, an alternative embodiment includes for the axis of the said barrel, 4, and said piston, 9, to be eccentric (and parallel) to the common axes of all the other the said working components of the syringe.

Preferably a guide, 16, is provided in the said finger grip end of the said eccentric barrel, 4e, to ensure adequate alignment of axes of all the other working components.

Preferably the said eccentric construction provided conforms to 9S 5081 part 1, and/or any accepted medical standards prevailing.

Additionally the said needle holder tube, 2, is provided with at least 1 hole, 2h, to facilitate the release of trapped air when the syringe is being primed prior to injection.

Claims

CLAIMS:

1. A disposable hypodermic syringe comprizing a separate attachable hub wherein the said hub embodies a concentric mating needle holder with an internal integral hypodermic needle, wherein said holder is separable from the hub, and fully retractable (after use) into a (significantly) non-deform able syringe barrel (or syringe cylinder), the needle holder being provided with means for engaging a mating means provided at the end of the plunger (or piston rod) to facilitate said retraction.

2. As in claim I, wherein the mating engaging means provided at the end of the plunger comprizes a fluted and/or necked shaft terminating with an integral domed and/or button shaped head.

3. ecd S s 1 and 2 wherein the engaging means provided on the needle holder comprizes a tube having a mating internal diameter with the said domed head of the plunger, and provided with internal integral sprung barbs formed out of the wall of the tube, and so provided to enable entry of the said domed head until the said barbs spring back internally onto the said fluted neck behind the said domed head to entrap the said domed head.

4. As in all the above claims wherein means to make the needle and the needle holder tube integral are by the provision of an inert jointing medium, and/or integral inert plastic moulding.

5. As in all the above claims, wherein before retraction (of the needle and needle holder) into the barrel is desired, the said domed head of the plunger is retained behind the piston face and within the piston by a rubber (or synthetic rubber) membrane so provided to form the piston head or pressure face of the piston.

6. As in all the above claims wherein said membrane in claim 5, comprizes an integral moulding with the piston and/or piston sealing rings.

7. As in all the above claims wherein mating means between said needle holder tube and said hub is by the provision of an external screw thread on the needle holder tube and a mating internal thread on the corresponding mating section of the hub.

8. As in all the above claims wherein the said hub is manufactured in an inert plastic material and the said mating thread tolerances and said mating thread form mentioned in claim 7 are so provided to form an airtight and/or a liquid tight seal, and are at the same time unscrewable by twisting the said plunger after it is entrapped by the said barbs acting against the flutes of the said fluted plunger shaft.

9. As in all the above claims wherein the said piston is provided with an internal concentric tube provided with internal integral sprung barbs formed out of the wall of the tube and so provided to enable entry of the said plunger domed head (during manufacturing assembly) into the piston until the said piston tube barbs spring inwardly behind the said domed head, on to the neck of the plunger, to entrap the domed head and facilitate withdrawal of the piston during the suction stroke of the syringe.

10. As in all the above claims wherein the length of the said neck section of the plunger is so provided so as to permit sufficient forward movement of the plunger to enable penetration beyond the said piston head and into the said needle holder tube barbs (when said needle engagement/retraction is required).

11. As in all the above claims wherein the said hub is attached to syringe barrel by the provision of a concentric mating tapered shaped male nozzle on said syringe barrel and the provision of a matching air tight and/or liquid tight internal taper within said hub.

12. As in claim 11, wherein the gradient of the said taper used is 6% and/or any standard taper to conform with the accepted medical standards prevailing.

13. As in all the above claims wherein finger grips are provided on the syringe barrel at the plunger operating end of the said barrel.

14. As in all the above claims wherein a concentric bush or collar is provided inside the said barrel at the said finger grip end, together with integral matching shoulder stops provided at suitable locations on both ends of the plunger rod, to act as a stop to prevent premature penetration of the said piston head membrane, and also to act as a stop to prevent premature dismantling of the syringe assembly during the suction stroke respectively.

15. As in claim 14 wherein the dimensional tolerances of the said bush is so provided that its outside mating diameter is an interferance (but movable) fit with the mating bore of the said barrel, and the inside mating diameter of the said bush is an easy slide fit with the said mating plunger rod.

16. As in claims 1@ and 15 wherein said bush or collar is provided with a circumferencial split to enhance feasibility of the said fits mentioned in claim 15.

17. As in all the above claims wherein a weak spot or weak section is provided on an appropriate location of the plunger rod to enable it to be broken off after the said needle holder and needle have been fully retracted (after use) into the said barrel.

18. As in all the above claims wherein the said hub and syringe barrel are additionally provided with a mating thread fitting to reinforce the said airtight and/or liquid tight seal between the said tapered nozzle fitting.

19. As in claim 18, wherein said mating screw thread fitting provided conforms with Sritish Standard 3930 part 2, and/or any accepted medical standards prevailing.

20. As in all the above claims wherein there is provided an during seal located around the said needle holder tube and between the end face of the said syringe barrel nozzle and the mating internal face of the said hub to secure as an additional liquid and/or airtight seal.

21. As in all the above claims wherein there is provided an additional O-ring seal located around the said needle and between the end face of the said needle holder mentioned in claim 3, and the mating internal face of the said hub to serve as an additional liquid tight and/or airtight seal.

22. As in all the above claims wherein the axis of the said barrel and said piston are eccentric (and parallel) to the common axes of all the other said working components of the syringe.

23. As in claim 22 wherein eccentric construction provided conforms to RS5081 part 1, and/or any accepted medical standards prevailing.

24. As in claims 22 and 23, wherein a guide is provided in the said finger grip end of the said eccentric barrel to ensure adequate alignment of axes of all the other working components.

25. As in all the above claims wherein the said needle holder tube is provided with at least one hole to facilitate the release of trapped air.

26. A disposable hypodermic syringe substantially as described herein with reference to and as illustrated in the accompanying drawings.