WO1989009075A1

WO1989009075A1 - Hypodermic needle retractor

Info

Publication number: WO1989009075A1
Application number: PCT/AU1989/000121
Authority: WO
Inventors: John Patrick Kite
Original assignee: Davsa Seventy-Fifth Pty. Ltd.
Priority date: 1988-03-22
Filing date: 1989-03-21
Publication date: 1989-10-05
Also published as: GB2234177A; NZ228388A; GB9020371D0; IE890887L; US5221262A; CN1036510A; IE62062B1; GB2234177B

Abstract

A hypodermic syringe (10) has a retractable needle (18) carried in a needle support (17) mounted on the end of the syringe body (11). The needle (18) is attached to a needle holder (22) which has a conical head (26) on its forward end. A passage (30) in the holder enables the needle bore to communicate through holes (29) in the holder (22) with the chamber (14). The plunger and piston assembly (32) has a piston (33) with a sealing cap (35) engaged therewith. The piston (33) has a forwardly extending tubular portion (39) defining an opening with a tapered wall (40) which engages over the head (26) to lock the head behind an abutment surface (41). At the same time a diaphragm (38) formed by the sealing cap (35) extending across the tubular portion (39) is ruptured so the chamber (14) is no longer sealingly enclosed.

Description

HYPODERMIC NEEDLE RETRACTOR

Background of the Invention

The present invention relates to a syringe an relates particularly to a hypodermic syringe incorporatin a needle retractor.

Syringes currently in use have a fixed needl which is kept or sealed with an appropriate shiel but which is otherwise permanently fixed to the syring body for use. After the syringe has been used fo the administration of a serum, an antibody or th like, a danger often exists with the exposed needl of the used syringe particularly if the needle ha not been safely capped. Also, there is a danger tha a used syringe may be reused in which case a dange exists of infection from the now non-sterile syringe

Background Art

Various solutions to the problem of an expose needle of a syringe, after use, have been proposed In United States Patent No. 4,026,287 to Haller, i is proposed to form the forward end of the barre of the syringe as a breakable end wall, the cannul mounted on the end wall being severable therefro upon retraction of the plunger of the syringe. This however, can lead to the breakable end wall breakin inadvertently during operation of the syringe or a a result of forces applied to the needle during use

Various patent specifications have suggeste an arrangement whereby the needle of the syringe i mounted in a hub and the syringe plunger can engag with the hub, such as by a screw threaded action to thereby withdraw the hub from the end of the syring barrel to retract the needle into the barrel. Suc arrangements as are shown in United States Paten No. 4,675,005 to DeLuccia, for 4,650,468 to Jenning 4,710,170 to Haber et. al. , 4,507,117 to Vining et al., and 4,592,744 to Walter. The structure of al these syringes is relatively complex, requirin arrangements for engagement of needles within needle holders, engagements of needle holders within syringe barrels so as to seal the needle within the barrel, means for engaging the plunger with the needle holder,

5 generally by a rotational, screw threading or bayonet attachment and relatively complex operation procedures to ensure the disclosed systems are effective.

United States Patent No. 4,770,655 to Haber et. al. discloses a syringe construction in which the

10 piston assembly has a detachable stem and a needle capturing receptacle which is axially and distally movable in the cylinder. When the piston is moved to the most distal aspect of the cylinder it selectively engages the needle. The piston is withdrawn to re-

15 locate the needle from the distal end to the proximal cylinder end. The needle capturing receptacle is locked at the proximal end of the cylinder with the needle cannula retracted within and shielded by the cylinder. The stem is detached from the piston assembly

20 and discarded. While the arrangement described is relatively simple, and therefore economical to produce, several actions are required in order to render the syringe relatively safe, one of those actions including breaking the stem from the piston assembly. It will

•*•*•^» be appreciated that un-intended stem breakage ca easily occur through mis-use of the syringe, and if the stem is not broken, the syringe can be reuse with relatively little difficultly.

Summary of the Invention

30 It is desirable to provide an improved constructio of hypodermic syringe which is economical to manufacture, has relatively few parts compared to the commonl used, fixed needle syringes, but allows the needl to be retracted and safely stored within the syring

35 for disposal;

It is another object of the present inventio to provide an improved hypodermic syringe which, afte use, cannot be reused without replacement parts It is another object of the present inventi to provide a hypodermic syringe which has a retractab needle and yet which also has a minimal free spac

It is also an object of the present inventi to provide a hypodermic syringe having retractable needle so as to lower the possibili of a used needle entering the skin of a person afte the syringe has been used.

Additional objects, advantages and features o ° the invention will be set forth in the followin description or will become apparent by practice o the invention. According to one particular aspec of the invention there is provided a syringe comprisin a tubular body open at one end and substantially close at the other end to provide a chamber, a needle mountin engaged with the said other end, a needle removabl mounted in said mounting, the needle having an inne end formed with engageable means, a piston means axiall movable within the body, said piston means havin gripping means to selectively grip said engageabl means when piston means is moved to the closed en of the body whereby subsequent movement of the pisto means away from the said closed end draws the needl into the chamber, and a frangible diaphragm on th piston means- which is broken with engagement of th engageable means with the gripping means.

In a preferred embodiment of the invention, th needle means includes a needle housing having a sub stantially axial passageway extending partway alon the housing from one end. A hollow needle is secure in the passageway, and at least one hole in the housin wall communicates with the passageway to allow flui to pass from the chamber through the needle. Th provision of the hole spaced from the inner end o the needle means is an important feature which provide an extremely small minimal volume when the pisto is moved to the end of the chamber.

The engageable means on the needle means preferabl comprises a substantially -conical or tapered hea mounted on the needle means so as to provide a radiall extending, annular shoulder. The gripping means in the preferred embodiment, comprises an axiall extending, hollow tubular part on the piston, th forward end of which has a tapering surface extendin outwardly from a cooperating, annular shoulder. I use, when the piston is moved axially in the chambe towards the needle means, the tapering surface engage with the head of the needle means and snaps over the head so that the cooperating annular shoulder engage behind the head on the needle means.

In one form of the invention, the needle mean is carried by a needle support removably attache to the needle mounting. This enables needle assemblie comprising the needle means and support to be replace on a syringe body. Thus, the body and piston mean can be reused with disposable needles. With thi arrangement, the needle support and the needle mountin are provided with cooperating means for snap engagemen thereof.

In an alternative arrangement, the needle suppor is fixed to the needle mounting for single use syringes

In order that the invention will be more readil understood, one embodiment thereof will now be describe with reference to the accompanying drawings.

Description of the Drawings

Figure 1 is a cross sectional view of a hypodermi syringe in accordance with the present invention wit the needle in the assembled position ready for us Figure 2 is a view similar to Figure 1 but showi the syringe with the needle withdrawn into the chambe

Figure 3 is a cross sectional elevational vi showing the syringe ready for disposal with t needle located within the plunger, Figure 4 is a detailed view of the needle e of the syringe showing the engagement of the pist with the needle, and

Figure 5 is a cross sectional view taken alo the lines V-V of Figure 1.

Description of the Preferred Embodiment

The drawings illustrate a hypodermic syring

10 having a retractable needle 18. In Figure 1 , ther is shown the syringe 10 comprising a syringe bod

11 having a cylindrical wall 12 extending to an integra needle mounting 13 which substantially closes on end of the body 11. The cylindrical wall 12 define a generally cylindrical chamber 14 which, in use contains a liquid to be injected which is expresse from the chamber 14 through a passageway 15 in th needle mounting 13 and through the needle 18.

The syringe 10 is provided with a piston an plunger assembly 32 located in the chamber 1 an axially movable therein. The assembly 32 include a plunger body 34 formed by four radially extendin elongated walls 34A terminating at an outer end i a finger piece 34B. Partway along the plunger bod 34, radially inner edges of the walls 34A define housing 34C.

A piston 33 is integral with the plunger 34 an is provided with a forwardly extending tubular portio 39 which communicates with the housing 34C. The tubula portion 39 terminates in a radially inwardly extendin abutment surface 41 from which an outwardly taperin surface 40 extends.

The piston 33 is formed with an annular flang 36 defining an annular groove 37 forming a seat fo a seal member 35. The seal member 35 is preferabl formed of a soft rubber material and contacts th inner surface of the cylindrical wall 12 of the syring body 11 to form a liquid seal therewith. The sea member 35 is in the shape of a cap, a central portion of which constitutes a frangible diaphragm or membran 38 engaged over the end of the tubular portion 39 of the piston 33. The seal member 35 therefor effectively seals the open end of the chamber 14 o the syringe 10 and prevents fluid within the chambe >

14 passing into the tubular portion 39 of the piston 33 and into the housing 34C.

The hypodermic needle 18 is fixed within an axial passageway 23 extending from one end of a needle housing 22. The passageway 23 communicates with a further passage 30 and substantially radially extending holes 29 which enable fluid to communicate from the syring chamber 14 through the hollow needle 18. The needle support 17 is provided with an annular rib 19 which o engages a corresponding groove in the needle mounting 13 to snap fit the support 17 in position. Alternatively, the needle support 17 may be fixed, as by gluing or welding, to the needle mounting 13.

Similarly, the needle housing 22 is formed with 5 an annular rib 31 which engages with a corresponding groove in the needle support 17 to hold the hypodermic needle 18 in the operative position. The needle support

17 is formed at its forward end with an annular shoulder 24 which engages the end of the needle housing 22 0 and prevents forward movement of the hypodermic needle

18 relative to the needle support 17.

The inner end of the needle housing is formed with a conical head 26 defining an annular shoulder 28. 5 In use of the hypodermic syringe of the invention, the piston and plunger assembly 32 is moved relative to the syringe body 11 to expel liquid within the chamber 14 through the annular space 15 which exist between the needle housing 22 and the needle mountin 0 13, through the holes 29, the passage 30 and the hollo needle 18. The diaphragm 38 engaged over the en of the piston 33 prevents liquid passing through th tubular portion 39 forming the end of the piston 33.

As the volume of the chamber 14 approaches it 5 minimal volume, the conical surface 27 of the hea 24 engages the diaphragm 38. Initially, and subjec to the elasticity thereof, the diaphragm 38 deform around the head 26 until the diaphragm ruptures Thereafter, the conical surface 27 on the head 2 engages the similarly shaped, cooperating surfac 40 on the tubular portion 39, expanding the end o the tubular portion 39 so that the head 26 snaps int the tubular portion 39. In this position, the abutmen surface 28 engages the corresponding surface withi the tubular portion 39 thus engaging the needle assembl with the piston and plunger assembly 32.

Movement of the piston and plunger assembly 3 axially in the syringe body 11 away from the needl mounting 13 causes the needle housing 22 and attache hypodermic needle 18 to be withdrawn into the chambe 14. Such movement causes the annular rib 31 on th needle housing to disengage from the correspondin groove. In an alternative construction, where n such rib is provided and the needle housing i frictionally held in the needle support 17, th withdrawing forces are sufficient to overcome th frictional holding forces. As the piston and plunge assembly 32 is continually withdrawn to the positio illustrated in Figure 2, the needle 18 is drawn full into the chamber 14 so as to be located entirely therein The piston and plunger assembly 32 are then move forwardly, or the syringe 10 is held vertically wit the piston mounting uppermost, so that the needl 18 and needle housing 22 fall into the housing 34 within the plunger body 34. The piston and plunge assembly 32 can then moved to the position shown i Figure 3 so that the needle and needle housing ar captively contained within the housing 34C for saf disposal. _

It -will be appreciated that any attempt to reus the syringe will fail due to the ruptured diaphrag 38 preventing pressure being developed within th chamber 14. It will be noted that the housing 34 within the plunger body 34 has openings which communicat with atmosphere. Thus", the provision of the frangibl diaphragm ensures that the syringe can be used onc only without replacement of the seal member.

The structure of the syringe of the present inventio is substantially similar to the structure of fixe needle syringes currently in use. Accordingly, th present invention requires minimum re-tooling o modification of existing tooling to be put into practice Further, it is not necessary for the operator to g through a sequence of operations, such as twistin of the piston and plunger assembly relative to th syringe body, in order to engage the piston with th needle. The simple action of using the syringe auto raatically engages the piston with the needle and simple withdrawing of the piston and plunger assembl retracts the needle into the syringe body.

It is envisaged that, subject to cost considerations automatic retraction of the needle may be provide by mounting a compression spring on the syringe bod and biasing the piston and plunger assembly to th outer position. With such a spring biasing arrangement the operator uses the syringe to inject the flu and the spring automatically acts to retract the pist and plunger assembly and the attached hypodermic needl into the syringe body without the need for specifi operator action.

Claims

1. A syringe comprising a tubular body open at o end and terminating at the other end in a needle mounti to provide a chamber, a needle means removably mounte in said mounting to project away from said body, th needle means having an inner end formed with engageabl means, piston means axially movable within the chamber said piston means having gripping means to selectivel grip said engageable means when the piston is move within the chamber to the said other end of the bod whereby subsequent movement of the piston means awa from the said other end draws the needle means int the chamber, and a frangible diaphragm means on th piston means, the diaphragm means being broken upo engagement of the gripping means with the engageabl means.

2. A syringe according to claim 1 wherein said needl means includes a needle housing having a substantiall axial passageway extending partway along the housin from one end thereof and a hollow needle secured i the passageway, and at least one hole in the housin wall communicating with the passageway.

3. A syringe according to claim 2 wherein sai engageable means comprises a substantially conica or tapered head on the other end of the needle housin defining a substantially radially outwardly extending annular shoulder.

4. A syringe according to any one of claims 1 t 3 wherein said needle means is carried by a needl support removably attached to the needle mounting the needle support including shoulder means to engag corresponding shoulder means on the needle mean preventing movement of the needle means axially o the support away from the body.

5. A syringe according to claim 4 wherein said needl means engages within an axial bore in the needle support the bore diameter and length being such as to frictionall hold the needle means in assembled position for use

6. A syringe according to claim 4 wherein said needl means is provided with an enlargement which engages a corresponding groove in the needle support to hold the needle means in assembled position for use.

7. A syringe according to any one of the preceding claims wherein the gripping means comprises a tubular extension on the piston means and terminating in a tapered surface extending radially outwardly from a radial abutment surface, the abutment surface adapted to lock behind a corresponding surface of the engageable means.

8. A hypodermic syringe comprising: a body having a cylinder terminating at one end with a needle mounting and providing a chamber to receive a liquid to be injected; a needle removably mounted in said mounting and having a terminal end located in said chamber, said terminal end having engageable means; a piston slidably sealingly located within said chamber and longitudinally movable of said cylinder so as to vary the volume of said chamber; operator manipulable means extending from said piston so that a user may cause reciprocation of said piston; wherein said piston includes gripping means to engage said terminal end when said chamber provides a minimum volume, so that subsequent movement of sai piston to increase the volume of said space draws said needle into said chamber.

9„ The syringe of claim 8 wherein said engageabl means includes a head with an abutment surface, an said gripping means includes an abutment surface t engage the abutment surface of said head.

10. The syringe of any one of claims 8 or 9 wherei said piston includes a seal member which slidabl sealingly engages said cylinder, said seal membe including a frangible diaphragm which is puncture by said engageable means when said gripping mean is moved into engaging contact with said engageabl means.

11. »

The syringe of any one of claims 8 to 10 further includin a needle assembly incorporating said needle, sai needle assembly including a needle housing withi which said needle is secured, said needle housin being provided with said engageable means, a suppor to which said needle housing is removably attached with said needle support being attached to said needl mounting.

12. The syringe of claim 11 wherein said needle housin is secured to said support by friction, which frictio is overcome when said engaging means draws the needl into said chamber.

13. The syringe of claim 11 wherein said needle housin is mounted in said support by interengaging annula rib and groove.

14. A needle assembly to be secured to a needle mountin of a hypodermic syringe, said assembly including a needle support to be secured to said mounting and being provided with a passage to communicate wit the interior of said syringe so as to receive a liqui therefrom to be injected; a needle housing mounted within said passag and removably secured to said support, said housin being provided with engageable means to project t the interior of said syringe to a position wherea it can be engaged by a piston assembly of the syringe

15. The needle assembly of claim 14 wherein sai needle is removably attached to said support by a adhesive.

16. A syringe substantially as hereinbefore describe with reference to the accompanying drawings.