WO2004101036A1

WO2004101036A1 - Fluid handling devices

Info

Publication number: WO2004101036A1
Application number: PCT/GB2004/002081
Authority: WO
Inventors: Jeremy Francis Donnan
Original assignee: Nmt Group Plc
Priority date: 2003-05-16
Filing date: 2004-05-14
Publication date: 2004-11-25
Also published as: TW200507895A; GB0311226D0

Abstract

A fluid handling device comprises a barrel (4), a hollow needle (10) projecting from the barrel, a hollow plunger (6) slidable within the barrel towards the needle to effect expulsion of liquid from the barrel through the needle, a needle retraction mechanism (8) operable to retract the needle, after use, from the projecting position to an inaccessible position within the hollow plunger (6), and a closure member located at the forward end of the plunger and having a dislodgeable locking portion (26) which is dislodged to permit the needle to enter the hollow plunger upon operation of the needle retraction mechanism. The closure member (22) is a snap-fit within the forward end of the plunger (6). It includes a seal (44) which is in sealing engagement with the internal surface of the barrel and also serves as a seal between the closure member and the hollow plunger. The closure member (22) has a surface (55) which, as the plunger completes its forward stroke, is arranged to contact a surface (80) of a restrainer (74) of the needle retraction mechanism (8) in order to displace the restrainer and release the needle for retraction. This surface is bounded by a border (50) which, as the plunger approaches completion of its stroke, is arranged to enter an annular space (84) between the retainer and the barrel (6) so as to reduce the space available for liquid retention and allow for more complete expulsion of liquid from the barrel.

Description

FLUID HANDLING DEVICES

This invention relates to fluid handling devices, such as hypodermic syringes, employing hollow needles through which liquid flow is conducted. The invention is particularly concerned with such devices of the kind comprising a barrel, a hollow needle which projects from the barrel, a hollow plunger movable within the barrel towards the needle to effect expulsion of liquid from the barrel through the needle, a closure member located at the forward end of the plunger and having a dislodgeable blocking portion, and a needle retraction mechanism operable to retract the needle after use from the projecting position to an inaccessible position within the hollow plunger, needle retraction being preceded or accompanied by dislodgement of the blocking portion to allow entry of the needle into the hollow plunger. Such devices are disclosed in our prior specifications EP-A-776 225 and WO 01/42 104. The present invention seeks to provide improvements which facilitate automatic assembly of such fluid handling devices.

According to one aspect of the present invention there is provided a device of the type described in which the closure member is engageable as a snap fit with the forward end of the plunger. This allows for high speed assembly of the closure member to the plunger.

According to another aspect of the present invention there is provided a device of the type described in which a seal associated with the forward end of the plunger is arranged for sealingly contacting the internal surface of the barrel and is mounted on or integral with the closure member. This aspect also allows for simplification of the assembly procedure, especially when automated.

The closure member in this aspect of the invention may be engageable as a snap fit with the forward end of the plunger.

The closure member may include a portion which is received within the forward end of the plunger, such portion being able to snap into engagement with the plunger. The seal may be so arranged that it sealingly contacts the internal surface of the barrel and also effects a seal between the closure member and the plunger in order to prevent ingress of liquid into the interior of the plunger. Thus, the seal may at its outer periphery contact the internal surface of the barrel and may at its inner periphery sealing contact the closure member to provide the seal with the plunger.

The closure member and the plunger may have co-operating formations for effecting the snap fit. The formations may comprise a male formation or formations on one component and a female formation or formations on the other. The male formation or formations may be wedge-shaped such that the wedge surface slopes inwardly in the rearward direction, i.e. the direction of movement of the closure member relative to the plunger during push fitting the closure member on to the plunger.

The seal may be located on a rim portion of the closure member. It may be moulded in situ on the rim portion, e.g. during production of the closure member by a 3 shot moulding technique. Alternatively, it may be formed integrally with the closure member.

The seal may be constrained against movement in the forward direction by a shoulder on the closure member. The arrangement may be such that, when the seal is produced as a separate component, it may be assembled to the closure member by passing it forwardly over the closure member from the rear end of the latter. In assembling the seal to the closure member, it may ride over the snap fitting formation or formations on the closure member and/or over a ramp formation so that the seal is gradually expanded and then resiles into a channel or groove located rearwardly of the shoulder on the closure member. ^• !. In a further aspect of the invention, the plunger co-operates with the needle retraction mechanism via a surface which, as the plunger approaches completion of its forward stroke, is arranged to contact a surface of a restrainer forming part of the needle retraction mechanism so that the restrainer is displaced to release the needle for retraction, said surface of the plunger being encircled by a border which, as the plunger approaches or reaches completion of its stroke, is arranged to enter an annular space between the restrainer and the barrel thereby reducing the space available for liquid retention and allowing more complete expulsion of liquid to be effected.

The surface of the plunger cooperating with the needle retraction mechanism may be provided by the closure member, typically, by the rim portion of the closure member.

The restrainer may be sealingly engaged with the barrel adjacent the forward end of the latter through the agency of a lip seal. The latter may be formed integrally with the barrel and may comprise a resilient annular projection which extends radially inwardly and is directed rearwardly.

The restrainer may co-operate with a hub mounting the needle, the hub being urged rearwardly, e.g. by spring means, but normally restrained from such rearward movement until the retraction mechanism is triggered by the plunger. The restrainer and the hub may be coupled together in any suitable manner allowing release of the hub at the desired point in plunger travel, e.g. the plunger and hub may be coupled together as disclosed in our prior International Specification No WO 02/87669, the entire disclosure of which is incorporated herein by this reference.

The invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a view of a hypodermic syringe in its charged condition prior to use;

Figure 2 is a perspective view of a plunger assembly for use in a syringe of the type illustrated in Figure 1 ; Figure 3 is an exploded view of the plunger assembly;

Figure 4 is an enlarged sectional view of the forward end of the plunger;

Figure 5 is a fragmentary sectional view of the forward end of the syringe with the plunger shown approaching the end of its stroke; and

Figure 6 is a similar view to that of Figure 5 but showing the plunger at the end of its forward stroke. The disposable hypodermic syringe shown in the drawings may be generally similar to that described and illustrated in our prior EP-A-776225 and/or WO 01/42 104, the disclosures of which are incorporated herein by reference. Referring now to the drawings, the disposable syringe 2 comprises a generally cylindrical barrel 4, from the rear of which (upper end as viewed in Figure 1 ) protrudes a plunger 6. At the lower end of the barrel 4 is provided a needle unit 8 of the retractable type including a forwardly projecting hollow needle 10 which can communicate with a chamber located between the forward end of the barrel 4 and the forward end of the plunger 6.

The plunger 6 is hollow and terminates at its trailing end in an enlarged head 20 to which force can be applied by means of the user's thumb while holding the syringe with two fingers bearing against the finger-engaging flanges 12 on the barrel 4. The applied force is used to depress the plunger into the barrel so that the liquid contents of the barrel are forced through the hollow needle, e.g. after the latter has been inserted into a patient.

Referring now to Figures 2 to 4, the forward end of the plunger 6 is fitted with a closure member 22 of the form disclosed in WO 01/42104 to which reference should be made for full details. For present purposes, it will be noted that it comprises an outer rim portion 24 and a central blocking portion 26, the two parts being produced by a two shot moulding process in such a way that the blocking portion 26 is sealingly engaged within the rim portion 24 and can, on application of a suitable axial force during operation of the syringe, be dislodged from the rim portion 24 to allow the needle to be driven into the interior of the plunger 6 by means of a needle retraction mechanism of the type disclosed in EP-A-776225 or WO 01/42104.

To facilitate automatic assembly of the closure member 22 to the plunger 6, the components are designed to fit together as a snap fit such that one or more formations on the rim portion 24 snap fit into a corresponding formation or formations at the forward end of the plunger. The closure member may for example be provided with a male formation or formations while the plunger may be provided with a female formation or formations, or vice versa or a mixture of both.

In the illustrated embodiment, the rim portion 24 of the closure member 22 is provided with a male formations 30 of wedge-shaped configuration in axial section which are received in female formations 32 in the plunger 6, the female formations being illustrated as apertures separated from each other by axial legs 34 which connect an annular collar 36 to the main body of the plunger.

The male formations 30 are located at the rear end of the rim portion 24. A projecting annular shoulder 38 is provided intermediate the forward and rear ends of the rim portion 24 and a groove 40 is provided between the shoulder 38 and annular ramp 42 for reception of a resilient annular seal 44. The internal surface 46 of the collar 36 is of part-conical shape for co-operation with a complementary surface 48 on the ramp 42.

When the closure member is snap fitted to the plunger 6, the seal 44 makes sealing contact at its inner periphery with the rim portion 24 to seal the interior of the plunger against ingress of liquid from the chamber defined between the barrel and the plunger. The outer periphery of the seal 44 also serves to make sealing contact with the internal cylindrical surface of the barrel 4 to confine the liquid contents of the barrel to the space between the seal 44 and the forward end of the barrel.

A feature of the design is that the seal 44 fulfills two sealing functions and may be assembled to the closure member prior to snap fitting the latter to the plunger so that the operation of fitting of the closure member also results in fitting of the seal 44. Assembly of the seal is also facilitated by the ramp 42 since the seal can be pushed onto the rear end of the rim portion and then pressed forwardly so that it is forced to ride up and gradually expand over the ramp 42 (and the male formation 30) until it reaches the groove 40 into which it resiles. Thus, the closure member and seal can be pre-assembled and subsequently fitted to the plunger in one operation thereby avoiding the need to fit them separately. Forwardly of the shoulder 38, the rim portion 24 includes a forwardly projecting wall or border 50 having a leading end 52 and a rebate 53 with a base 55 located rearwardly of the leading end 52 . The base 55 of the rebate 53 is designed to co-operate with the needle retraction mechanism (i.e. in the manner disclosed in EP-A-776 225 and WO 01/42 104) as the plunger approaches the limit of its forward movement during expulsion of the liquid from the barrel through the needle.

Referring to Figures 5 and 6, these respectively show the plunger 6 as it approaches and after it has reached its fully depressed condition. In Figure 5, the needle 10 is in its operative position in which its mounting hub 70, spring loaded by spring 72, is restrained against rearward movement by co-operation between the hub 70 and a restrainer 74. The hub and restrainer are coupled together, for example by two shot moulding as disclosed in our prior International specification WO 02/87669, in such a way that, when the plunger reaches or approaches the end of its stroke (see Figure 6), the hub 70 is released from the restrainer 74 to allow the needle and hub assembly to be driven rearwardly by spring 72. At about the same time, the blocking portion 26 is dislodged from the rim portion 24 so that the needle and hub assembly can be projected into the interior of the plunger 6, as disclosed in WO 01/42 104 and WO 02/87669.

The restrainer 74 makes sealing engagement with a lip seal 76 located adjacent the forward end of a reduced diameter section 78 of the barrel 4. The lip seal 76 is formed integrally with the barrel and comprises a resilient annular projection which extends radially inwardly and is directed rearwardly. In accordance with a feature of the present invention, the plunger 6 cooperates with the restrainer 74 through engagement of the base 55 of the rebate 53 with the trailing end 80 of the restrainer 74 so that the border 50 enters the space 84 between the cylindrical trailing portion 82 of the restrainer 74 and the inner surface of the barrel proximate the lip seal 76. In this way, the border 50 serves to reduce the space available for fluid retention within the barrel thereby allowing more complete expulsion of the liquid during the injection of the plunger. The cross-sectional shape and dimensions of the border 50 may be appropriately designed to reduce the space available for liquid retention.

To further minimise spillage, the closure member is provided with one or more apertures/channels 60 communicating the space within the wall 50 with the space without so that, when the face 52 contacts the needle retraction mechanism, liquid flow to the needle can be maintained via the aperture(s) 60. It will be noted that when the plunger is in its fully depressed condition, a conically shaped annular shoulder 86 of the rim portion 24 is proximate a correspondingly shaped shoulder 88 leading to the reduced diameter section 78 of the barrel 4. Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance, it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features disclosed herein and/or shown in the drawings whether or not particular emphasis has been placed on such feature or features.

It will also be appreciated that the invention is not limited to the embodiment specifically described and that various modifications are possible. For example, in the illustrated embodiment, the seal is a separate component which is assembled to the closure member after the latter has been manufactured. In one modification, the seal may be produced by moulding it in situ during the production of the closure member, e.g. a 3 shot moulding process. In another modification, the seal may be formed integrally with the rim portion of the closure member.

Claims

1. A fluid handling device (2) comprising a barrel (4), a hollow needle (10) projecting from the barrel, a hollow plunger (6) slidable within the barrel towards the needle to effect expulsion of the liquid from the barrel through the needle, a needle retraction mechanism (8) operable to retract the needle, after use, from the projecting position to a position within the hollow plunger (6), and a closure member (22) located at the forward end of the plunger and having a dislodgeable blocking portion (26) which is dislodged to allow entry of the needle into the hollow plunger (6), characterised in that the closure member (22) is engageable with the forward end of the plunger (6) by means of a snap-fit.

2. A device as claimed in claim 1 , in which the closure member (22) includes a portion (24) which is a snap-fit within the forward end of the plunger (6).

3. A device as claimed in claim 2, in which the closure member (22) and the plunger (6) have cooperating formation for effecting the snap-fit, said formations comprising at least one male formations (30) on one of the closure member and the plunger and at least one cooperating female formation (32) on the other one of the closure member and plunger.

4. A device as claimed in claim 3, in which said at least one male formation (30) is wedge-shaped with the wedge surface sloping inwardly in a direction away from the forward end of the plunger (6).

5. A device as claimed in any one of the preceding claims, in which the closure member (22) has a seal (44) in sealing contact with the internal surface of the barrel (4).

6. A device as claimed in claim 5, in which the seal (44) also serves as a seal between the closure member (22) and the hollow plunger (6) in order to prevent ingress of liquid into the interior of the plunger.

7. A device as claimed in claim 5 or 6, in which the seal (44) is located on a rim portion (24) of the closure member (22).

8. A device as claimed in claim 7, in which the seal (44) is moulded in situ on the rim portion (24) of the closure member or is formed integrally with the rim portion.

9. A device as claimed in any one of the preceding claims 5 to 8, including a shoulder (38) on the closure member (22) for constraining the seal against movement in a forward direction away from the forward end of the plunger (6).

10. A device as claimed in claim 9, in which the seal (44) is a separate member and the closure member (22) is configured such that the seal is assembled to the closure member by advancing it forwardly over the closure member from the rear end thereof.

11. A device as claimed in claim 10, in which the closure member (22) has an annular groove (40) located rearwardly of the shoulder (38) and, when assembled to the closure member, the seal (44) rides over the snap-fitting formation(s) (30) of the closure member, and/or a ramp formation (42) rearwardly of the groove, so that the seal is gradually expanded and then resiles into the groove.

12. A device as claimed in any one of the preceding claims, including a surface (55) disposed on the closure member (22) and via which the plunger (6) cooperates with the needle retraction mechanism (8) as the plunger completes its forward stroke, said surface (55) being arranged to contact a surface (80) of a restrainer (74) forming part of the needle retraction mechanism in order to displace the restrainer and release the needle (10) for retraction, and said surface (55) of the closure member being bounded by a border (50) which, as the plunger completes its stroke, is arranged to enter an annular space (84) disposed between the restrainer and the barrel (4) in order to reduce the space available for liquid retention.

13. A device as claimed in claim 12, including a lip seal (76) adjacent the forward end of the barrel (4) for effecting a seal between the restrainer (74) and the internal surface of the barrel.

14. A device as claimed in claim 13, in which the lip seal (76) is formed integrally with the barrel (4) and comprises a resilient annular projection extending radially inwardly and rearwardly of the barrel.

15. A fluid handling device comprising a barrel (4), a hollow needle (10) projecting from the barrel, a hollow plunger (6) slidable within the barrel towards the needle to effect expulsion of liquid from the barrel through the needle, a needle retraction mechanism (8) operable to retract the needle (10), after use, from the projecting position to a position within the hollow plunger, a closure member (22) located at the forward end of the plunger (6) and having a dislodgeable blocking portion (26) which is dislodged to enable entry of the needle into the hollow plunger, and a seal (44) adjacent the forward end of the plunger in sealing contact with the internal surface of the barrel, characterised in that the seal (44) is disposed on the closure member (22).

16. A device as claimed in claim 15, in which the seal (44) also serves as a seal between the closure member (22) and the hollow plunger (6) in order to prevent ingress of liquid into the interior of the plunger.

17. A device as claimed in claim 15 or 16, in which the seal (44) is located on a rim portion (24) of the closure member (22).

18. A device as claimed in claim 17, in which the seal (44) is moulded in situ on the rim portion (24) of the closure member or is formed integrally with the rim portion.

19. A device as claimed in any one of the preceding claims 15 to 18, including a shoulder (38) on the closure member (22) for constraining the seal against movement in a forward direction away from the forward end of the plunger (6).

20. A device as claimed in claim 19, in which the seal (44) is a separate member and the closure member (22) is configured such that the seal is assembled to the closure member by advancing it forwardly over the closure member from the rear end thereof.

21. A device as claimed in claim 20, in which the closure member (22) has an annular groove (40) located rearwardly of the shoulder (38). and, when assembled to the closure member, the seal (44) rides over a ramp formation (42) rearwardly of the groove, so that the seal is gradually expanded and then resiles into the groove-

22. A device as claimed in any one of the preceding claims 15 to 21 , including a surface (55) disposed on the closure member (22) and via which the plunger (6) cooperates with the needle retraction mechanism (8) as the plunger completes its forward stroke, said surface (55) being arranged to contact a surface (80) of a restrainer (74) forming part of the needle retraction mechanism in order to displace the restrainer and release the needle (10) for retraction, and said surface (55) of the closure member being bounded by a border (50) which, as the plunger completes its stroke, is arranged to enter an annular space (84) disposed between the restrainer and the barrel (4) in order to reduce the space available for liquid retention.

23. A device as claimed in claim 22, including a lip seal (76) adjacent the forward end of the barrel (4) for effecting a seal between the restrainer (74) and the internal surface of the barrel.

24. A device as claimed in claim 23, in which the lip seal (76) is formed integrally with the barrel (4) and comprises a resilient annular projection extending radially inwardly and rearwardly of the barrel.

25. A fluid handling device comprising a barrel (4), a hollow needle (10) projecting from the barrel, a hollow plunger (6) slidable within the barrel towards the needle to effect expulsion of liquid from the barrel through the needle, a needle retraction mechanism (8) operable to retract the needle, after use, from the projecting position to a position within the hollow plunger (6), said plunger being closed at its forward end and having a dislodgeable blocking portion (26) which is dislodged to allow entry of the needle into the hollow plunger (6), characterised in that the plunger (6) cooperates with the needle retraction mechanism (8) via a surface (55) which is arranged to contact a surface (80) of a restrainer (74) of the needle restraining mechanism, as the plunger (6) completes its forward stroke, in order to displace the restrainer and release the needle for retraction, said surface (55) being bounded by a border (50) which, as the plunger approaches or reaches completion of its stroke, is arranged to enter an annular space (84) between the restrainer and the barrel (4) whereby to reduce the space available for liquid retention.

26. A device as claimed in claim 25, in which the surface (55) and border (50) are disposed on a closure member (22) which serves to close the forward end of the plunger (6) and which supports the dislodgeable blocking portion (26).

27. A device as claimed in claim 25 or 26, including at least one opening (60) connecting the space within the border (50) with the space without so that, when the surface (55) contacts the needle retraction mechanism (8), liquid flow to the needle (10) can be maintained via the opening(s) (60).